Primates

Text © Prof. Angelo Messina

 

English translation by Mario Beltramini

 

The Primates are an order of the class of the Eutherian Mammals (Mammalia Eutheria) where the development of the psychic faculties and capacities of manipulation has reached the highest known levels in the animal world.

For such a reason, traditionally, they are placed at the apex of the evolutionary scale of the animals, hence the scientific name of Primates, from the Latin “primus” (the best).

Actually, that of the Primates is a rather complex order and for some reasons still controversial, especially, but not only, for what concerns its systematic position.

As a matter of fact, several scholars conversely attribute to the Ungulates the highest grade of evolution and put the Primates much lower in the evolutionary scale, just after the orders of the Insectivores and of the Chiroptera.

In this phylogenetic vision, the tree shrews, that some Authors deem as standing amongst the most primitive Primates, in light of new data about the reproduction and the embryonic development, are instead ascribed by other scholars to an order of its own, that of the Scandentia.

In any case, regardless of systematic placement doubts, the fact remains that from the morphological point of view, the Primates form an extremely polymorphic order to which, besides the above mentioned tree shrews, are traditionally ascribed very known forms such as, Lemurs, Prosimians and Simians.

Biologically, belongs to this also the genus Homo, presently represented by only one extant species, the Homo sapiens (Linnaeus, 1758) to which we also belong. As it will be said later, also for the genus Homo various opinions do exist.

The Primates include a little less than 200 species of very various dimensions fluctuating between those of the tiny Lemur of the Kirindy Forest in Madagascar, the Pygmy mouse lemur, Microcebus myoxinus (Peters, 1852), that with its height of just 9 cm per 30 g of weight is the smallest among Mammals, to those of the Western gorilla of Africa Gorilla gorilla (Savage & Wyman 1847), that may reach, and even exceed, the 180 cm of height and weighs, averagely, 150-180 kg.

It is to be kept in mind that between these extreme forms of the order exist so many marked morphological differences that practically render impossible the formulation of a single criterion for characterizing the whole group. As previously mentioned, among all, the Tree shrews differ from the other Primates in a remarkable way and are inserted in this order only in consideration of their presumed origin and for some structural peculiarities of their skull. Definitely, the only characteristic that unites with certainty all species of Primates is their adaptation to the life on the trees.

Distinctive characters

Generally speaking, the basic morphological, anatomic and behavioural characteristics that unite the Primates may be summarized as follows.

They are placental Mammals, plantigrade and pentadactyl, with thumb and big toe almost always opposable, hence also the term of quadrumanes.

The collarbone is always present and in the forearm ulna and radius are not united and allow ample movements of pronation and of supination.

The body is mostly covered by a thick and compact fur, except for the human species where it is very reduced.

The tail is present in most species and has various development and shape; it mainly carries on functions of balance during the movements on the trees, to which, in some species, like in those of the family of the Cebidae, associates the capacity of prehensility.

Few members of the order, like those of the Hylobatids (Gibbons, Siamangs) and of the Hominids (Gorilla, Orangutan, Chimpanzee), have no tail: also the man, together with the congener extinct species, does not have it but keeps in the coccyx a vestigial remain of the tail of the ancestors from which it got origin.

The mammary glands are usually two and are located in the pectoral region; an exception are the Prosimians with the family of the Daubentoniids where the mammals are placed in inguinal position and with that of the Galagids who have 3 pairs of mammary glands placed in pectoral and inguinal position.

The external genitalia of the females present various generic and even specific peculiarities, but the clitoris is always present: this, in many Prosimians and in some Simians encloses in its extremity a penile bone, simple or bifid.

The uterus is simplex or bicornuate. In some species, like in the Prosimian Galago senegalensis (E. Geoffroy, 1796), the females have the vaginal opening that keeps closed for long periods, preventing in this way the mating.

In the males, unlike most Mammals, the penis is not united with the abdominal wall and hangs outwards, usually in front of the testicles that are extra abdominal and contained in a pouch, the scrotum; an exception are various Prosimians, the Marmosets (Callithrix) and some Gibbons (Hylobates) where, conversely, the penis is located behind the scrotum. In some species of Lemurids, the testicles undergo marked changes in size in relation with the mating season.

Like in most placental mammals, the penis of almost all Primates is equipped in its distal portion with the so-called penile bone, variously developed, rudimental in the big monkeys, such as the Gorilla, or absent as is the case for the Man.

The dentition is not specialized and includes all types of teeth; it is basically formed by 32-36 elements, with the incisors in a number of no more than 2, and with the molars characterized by 4-5 tubercles, the Prosimian Aye-aye (Daubentonia madagascariensis Gmelin, 1788) stands out because having only 2 incisors in the upper dental arch and 2 in the lower one, wide and flat, very robust and continuously growing.

The digestive system is structured for an omnivorous, frugivorous or phytophagous dietary regime; depending on the diet mainly formed by vegetable substances, the caecum is rather long.

It is interesting to note that, close to characters representing a great evolutionary development, in the Primates remain others certainly primitive. Among the last ones, are not to be forgotten the collarbone and the pentadactyl limbs, characteristics, these ones, also present in the man.

We must not forget that none of the species of the order, not even the man, owns in bulk all the exposed characteristics, however in each of them at least are present potentialities in this regard.

Adaptations

From a behavioural point of view, preliminarily it is to be noted how, but the Tree shrews, all other Primates are capable of climbing trees clinging to the trunk and the branches with their hands and feet.

Actually, such capacity is found also in other Mammals but in the Primates it reaches the most distinctive expressions, assuming a huge phylogenetic importance.

In any case, It is beyond any doubt that the fundamental biological factor that has marked the evolutionary path, the anatomy and the Primates life itself should be identified rightly in their adaptation to the life on the trees that with them has achieved the levels of maximum specialization among all Mammals.

In fact, despite their great variety of forms, the adaptation to the arboreal environment of the Primates is connected with the common characteristic of having more flexible limbs, with hands and often also legs having strong prehensile skills, excepting the man where only the thumb has prehensibility, and with the fingers where the claws have transformed in nails. In all Primates the collarbones are always present and well developed and their presence, together with the pentadactyly, clearly represent elements of primitiveness.

In any case, it is rightly the life on the trees, with the multiple structural and behavioural diversities connected with such an adaptation, that has represented the main determinant factor of the admirable evolution of this order of Mammals.

However, regardless of the different evolutionary levels achieved by the various systematic groups into which they are divided, all Primates have maintained the primitive characteristic of climbing on the trunk of the trees and of moving and jumping from one branch to another holding on with hands and feet.

Such characteristic is conserved in any case: when they squirt fast through the branches during the night, as the Mycrocebids, as well as when they twirl like the Gibbons, or proceed slowly like the Loricates, or leap and jump like the Galagones and the Tarsi.

It is true too that not all Primates have remained to live on the trees. Few species, including man, due to a secondary evolutionary adaptation, have abandoned the arboreal environment and have gone on to lead terrestrial life; in this, for their new environment, some of these species have assumed a quadrupedal position and proceed on the ground like a cat or a dog, others, instead, have acquired a biped erect status and walk only on the legs, like the Monkeys of the family of the Hominids, like Gorillas and Orangutans and even Man.

But even these species that usually live on the ground, also those still maintaining a quadruped position, like the Lemur Catta, the Baboons and some Macaques, as well as those that have acquired a bipedal position, like the Gibbons, the Orangutans and the Gorillas, climb the trees clinging to the trunk and to the branches with the hands; also the men, despite having fully achieved the erect posture and having completely freed themselves from the tree life, climb the trees in the same way as everyone else in the other Primates.

This capacity forms the fundamental characteristic common to all members of the order; in fact, in any case the Primates characterize especially for being arboreal animals or that anyway still maintain evident acquisitions related to that environment. The Primates are born, develop and thrive on the trees, where they have attained skills that have made them the undisputed masters of the trees.

And albeit among the living species of the Primates only the Man has totally abandoned that environment, it is to be kept in mind that he in any case has inherited from his ancestors and maintained the main characteristics related to their life on the trees.

In fact, even if it has asserted as a totally terrestrial species, like all the members of the order, Homo sapiens still holds the traces of the old adaptation of his ancestors to the life on the trees in the prehensile hands, in the nails of the fingers and in the structure of the teeth; and still in the stereoscopic (three-dimensional) vision, in the reduced sense of smell, in the presence of a brain of remarkable size, and in many other particulars. Finally, also the species of the genus Homo can be considered as a product getting its origin from the life on the trees.

Sensory organs

For all Primates are fundamental and determinant for their evolution the modifications that have mainly interested in first instance the sensory organs, olfactory and visual, in conjunction with their arboreal life and with the progressive passage from nocturnal to diurnal habits.

It must be kept in mind that rightly the life on the trees, if on one side has allowed the progressive reduction of the sense of smell as main source of sensorial information, as a consequence to the fact that the odorous traces are short-lasting and are easy to interrupt in this type of environment, on the other side has selected acquisitions that favoured the improvement of the visual function and of the perception of the distance, indispensable requirements for the movements along the trees that often occurred at remarkable distance from the soil.

For their part, in conjunction with the progressive increase of the importance of the sense of sight, the eyes have undergone a moving to an anterior position, abandoning the lateral one, typical to many other Mammals; this has caused the acquisition of the capacity of covering overlapped fields of view ( stereoscopic vision).

Such faculty, which is of great importance especially in relation with the arboreal life, has been further enhanced, with the perception of the colour that reaches the top of the specialization in these animals.

Excepting the Prosimians where it is absent, in relation to their mainly nocturnal habits, the Primates stand among the few Vertebrates having a colour vision. The nictitating membrane is represented by a small plica in the inner corner of the eyes, vestigial remnant of the so-called third transparent palpebra that is well developed in the other vertebrates, such as amphibian fishes, reptilians and birds.

Bone structure

The orbital cavities, typically big and variously bent forward, are delimited by bones; excepting some fossil form they are configured as a complete ring and completely separated from the temporal fossa behind.

In turn, also the facial structure has been interested by progressive modifications as the eyes became more prominent and the muzzle was getting smaller.

Limbs

Another important acquisition that has contributed in determinant way to orient the evolutionary path of this group is represented by the gradual emancipation of the forelimbs from the function of the four-legged locomotion: this has favoured the important development of the hands that have specialized in a perfect gripping organ and, especially in the Man, also as organ of manipulation.

It still must be noted that in the present forms, the forelegs and the hind limbs, mainly plantigrades, pentadactyla, have long fingers and are usually equipped with flat nails, laminar or tegular (unguiculate).

This characteristic is exclusive of the Primates and only in some rare instance, like in the members of the Platyrrhini Monkeys of the subfamily of the Callitrichines (Callitrichinae), the fingers are armed with thin and long nails, similar to claws, but the big toe that has a wide nail shaped like a tile.

In this regard, however, it should be noted that the embryonic development proves that the claws in the members of this subfamily are not a primitive character, but take form following a secondary transformation of the nail. Moreover, it must be kept in mind that among the Prosimians, some species have the hands with one finger, the index (Lemurids and Lorisids), or with two fingers, index and middle (Tarsiids), with the nail modified shaped like a comb utilized for the body cleaning and the grooming.

The Ayé-ayé (Daubentonia madagascariensis Gmelin,1788) have the fingers of the hands and of the feet very long, especially the middle finger of the hands that is particularly thin and is utilized for cleaning the face, for combing and for scratching; all the fingers of this animal are armed with sharp claws excepting the thumb and the index that are provided with flat nails.

The thumb, and often also the big toe, are usually opposable, from this also the name of quadrumanes; in some cases the fingers are more or less reduced.

Moreover as previously said, the hands can make wide movements of pronation and of supination, thanks to the complete separation of the ulna and of the radius, features not negligible, having contributed amply to the evolution of the order.

Posture

Strictly correlated with the specialization of the hands, are the tendency to the straightening of the trunk and to the acquisition of the erect posture; this tendency manifests in various grades in the different groups, but fully realizes only in the Man.

These specializations must also be put in relation with the progressive shortening of the trunk and with the chest enlargement that has lost its primitive keeled conformation, typical to the other members of the class of the Mammals that lead a terrestrial life.

Nervous system

As a consequence of these and other selective pressures, the Primates have at the same time also established progressive and deep modifications at the expense of the brain structure.

Generally, with the life on the trees, if on the one hand, due to the minor importance of the sense of the smell resulted of scarce utility for following the odorous traces on the trees, the relevant nervous centres of the brain have met a gradual reduction, on the other side, due to the development of the visual capacities acquired with the frontalization of the eyes, the portion of the cervical cortex delegated to the integration and evaluation of the images, has grown in importance.

In turn, the acquisition of the stereoscopic vision and the influence of a new series of sensorial information coming from the capacity of manipulation of the objects, have caused an extraordinary development of the cerebral hemispheres and the appearance of the calcarine sulcus, deep fissure around which stands the primary visual area; in particular in the Primates the occipital lobes (seat of the visual centres) are very developed.

Also the cerebellum, the portion of the brain deeply correlated with the precision muscle movements, has started to become one of the most conspicuous formations of the Primates’ brain thus favouring the life on the trees that required an increase of agility and of muscle coordination. In relation to these evolutionary events, the encephalon has undergone a considerable development and differentiation and, in the same time, has occurred a gradual increase of the skull and a reduction of the facial skeleton.

It appears evident that, from a certain point of view, the increase of the sensory stimulations and the growth in sizes and in complexities of the brain have proceeded hand in hand. When it has been available a bigger number of sensory information, the development of the dimensions of the brain has been favoured. In turn, as soon as the brain became bigger and more complex, the increase of the sensory perceptions was favoured.

It is not possible to establish precisely at what moment of evolution of the Primates the higher mental functions, such as the symbolization and the conceptual thinking have appeared.

However, considering the fact that the quality level required for these functions is in any case remarkably high, we can deduce that such a level has been reached when the brain, under the action of multiple selective factors, has acquired a certain threshold of size and complexity.

It is therefore evident that the increase in size of the brain and of the cranial capacity form some of the central and exclusive themes of the evolution of the Primates.

In these animals, the grade of cerebral development increases as we gradually pass from the Lemurs to the Monkeys and, among these, to the Hominids where it reaches the top in the Man.

Feeding

Unlike the human species that concentrates its own feeding in the meals, the Primates devote much of their daily activity to the search of food.

Their diet is very varied and practically omnivorous, including a mixed nourishment, animal and vegetable, though with the progressive decrease of the importance of the the insectivorous diet for the benefit of the frugivorous and herbivorous ones.

This trend is linked to the transformations of the originally nocturnal habits, that in most species they turn diurnal under the stimulus of opportunity given by an easy finding of leaves, buds and fruits in arboreal environment.

It must be noted how usually the size of a primate is indicative of its diet being related to the energy needs: small Primates eat essentially insects, whilst the big Primates usually eat vegetables.

Many members of the order eat mainly insects, spiders, scorpions, centipedes, small reptiles, birds and mice, but also buds, fruits, leaves and soft pith of some plants. Only the Colobines, subfamily of the Cercopithecids, stand among the most exclusively herbivorous Primate and manage to live nourishing mainly of leaves, thanks to their highly specialized digestive system.

Also the most primitive Primates, like the Prosimians, that are essentially herbivorous, complete their diet with small animals, particularly insects and their larvae.

For their part, the capuchin monkeys (Cebus) look for small invertebrates under the bark or inside rotting trees; in turn the terrestrial species of Platyrrhine Monkeys are greedy of crickets and grasshoppers and turn the big stones up looking for ants, scorpions and centipedes, but they eat also corn and roots.

Also the most advanced Primates, such as Orangutans, Chimpanzees and Gorillas, have a diet mainly based on fruits, buds and leaves but that is completed with ants, termites, and small mammals, like small antelopes and even young monkeys.

Some species, like the Chimpanzees, go hunting occasionally and share their prey.

Others, more specialized, like the Marmosets, nourish of lymph and of gum resin, a substance formed by complex carbohydrate, that is secreted from the so-called rubber trees.

During the dry season, the Marmosets make up for the lack of fruit, by etching the bark of the rubber trees and eating the secretion getting out.

Due to daily visits, the incisions on the bark remain open in a way to obtain a continuous flow of the secretion.

The water is surely an essential component for all the species of the order; however, many Primates are able to quench their thirst with the water contained in the food, with the dew and with the rain.

Only a few species are obliged to go to the ponds and to the water streams at dusk, with the risk of falling victim to predators in ambush, such as crocodiles and pythons.

Many species drink directly leaning over the water, others collect the water with their hands or dip their arms and suck it from the wet hairs.

The majority of the Primates identifies the food mainly through sight, whilst the smell, also due to the reduction of the sense of smell, has only an occasional role.

The nocturnal species are guided to their animal prey by the sense of hearing that is particularly acute.

In any case, it is proved that memory plays an important role in the localization and in the distribution of the main sources of food.

Typically the Primates utilize the hands for seizing the food and take it to the mouth.

Usually they do not consume it on the spot, but they take it to a suitable place or, as the guenons do, store it into the cheeks provided of internal pouches.

Occasionally, in particular Baboons and Chimpanzees, are able to utilize stones for breaking the shell of the nuts, or sticks and other tools for reaching the food out of their reach, like twigs that, previously deprived of leaves and reduced to the right dimensions, they introduce like hooks in the nests of termites and of ants.

It has been observed that populations of Chimpanzees living in separate regions of Africa have behavioral habits and cultural traditions different and that these can be transmitted between the various groups as occurs between the human beings.

Reproduction

The most common sexual relations between the Primates foresee the promiscuity especially of polygynous type in the sense that a male mates with several females during the same reproductive season; the polyandric species where it’s the female that mates with several males are more rare, for instance we find them among the Marmosets and the Tamarins, Platyrrhine Monkeys of the family of the Capuchins.

As happens in many mammals, also in the primates the reproduction is limited to well defined periods in many species, even if there doesn’t exist a veritable and real mating season.

In this regard it is to be remembered that in various species, like in the Chimpanzee, when the environmental conditions are favourable, the females tend to reproduce more frequently and to wean the young more quickly.

The duration of the gestation varies depending on the species and especially on its size. In the Platyrrhines, the females of the Mouse lemurs (Microcebus) and of the Dwarf lemurs (Cheirogaleus) deliver after 2-3 months, whilst those of the bigger species, such as those of Cebus, Tarsius and Brachyteles, take 6-7 and even 8 months.

The females of the Catarrhine Monkeys have a gestation whose duration is included between the 5-6 months of the Colobuses to the 7 months of Baboons, Presbytis and Gibbons up to the 9 months of the Gorillas.

The smaller species, in addition to a shorter gestation period, characterize in delivering usually 2-3 and even more infants at the time, whilst the bigger ones normally give birth to only one newborn.

All Primates take care of their own infants for more or less long periods; in some species it is mainly the mother caring its own kid and often takes it with her, attached to its own fur, in others it’s the father, in still others like in the Baboons (Papio), besides the mothers, the kids are assisted and defended also by all the members of the herd.

Ethology

Several species of Primates have solitary habits, but others aggregate and disaggregate depending on the seasons and on the availability of food, others more form groups very cohesive and stable over time.

Usually, whilst the males tend to distribute in relation with the presence and the number of females and do or don’t aggregate in function to the possibility to control the access to one or more receptive females at the same time; otherwise, the females pay more attention in nourishing their own kids and distribute on the territory depending on the availability of food and associate more or less strictly, thus characterizing with their behaviour the species they belong to.

Apart from some species that have solitary habits, in most Primates establish more or less complex intraspecific social relations and frequently form groups of variable entity, temporary or stable, with rules and condivided hierarchies that favour a better defense against the predators and more possibilities to find food. Some species live in family groups formed by a reproductive couple and their progeny. Among these stand the Gibbons and the members of the genus Callicebus.

Between the members of a same group exist different social ranks: some individuals occupy positions of dominance that allow a greater access to the food reserves and to the possibility of reproducing, conversely, others are subordinate and live with greater difficulty.

The dimension and the composition of the social groups reflects the changeable balance among the individual strategies in response to the environmental and demographic changes and are also affected by the relations and the conflicts between the two sexes.

The Primates have developed several channels of communication, from the olfactory marking, to the body and face mimic, to the physical contact to the more or less sophisticated language.

Various species of Guenons are able to associate a concept with real words and utilize warning signs differently depending on the type of predator, leopard, raptors and snakes.

It has been demonstrated that Chimpanzees, Bonobos, Gorillas and Orangutans are capable of learning the language of the deaf-mute and to communicate with each other and with man by means of simple gesture sequences, to understand and to be understood in their requests.

Distribution

The Primates are diffused especially in the tropical and subtropical regions, but Australia.

Madagascar, with its variety of habitats, boasts one of the highest levels of biodiversity of Primates and the greatest number of endemisms in the world.

Unfortunately, due to the remarkable contraction of the areas that still have characteristics of naturalness, nowadays reaching the 5% of the original surface, the Malagasy prosimians are all in danger of extinction.

Presently, in Europe the order is represented only by a colony of Barbary macaque (Macaca sylvanus, Linnaeus, 1758), that lives, isolated, in the Rock of Gibraltar; vastly diffused in the European continent southern regions during the Plio-Pleistocene, about 5-6 million years ago, nowadays this species, threatened with extinction, presents a very restricted range, limited to Gibraltar, to residual areas of oak forests in Morocco and Algeria.

The present species attributed to the Primates, about 200, live almost entirely in tropical and sub-tropical forest environments, such as the rainforests, the savannah, the gallery forests; some species have secondarily adapted to temperate or sub-alpine environments like those of Japan, or the Chinese conifer forests, tolerating at times low temperatures and the presence of the snow.

Some, like the Gelada baboon (Theropithecus gelada, Rüppell, 1835), species endemic to Ethiopia, frequent the stony environments.

As a result of the continuous reduction of their natural habitats, some species go on looking for food in the cultivated environments or in the outskirts of cities, where they may cause damage to the cultivations.

CLASSIFICATION

The systematics of the Primates is not yet well defined not only at generic and specific level but especially for what concerns the systematic categories of superior, level, suborders and families. An old classification of the order, that despite being deemed of poor systematic value has entered current use, is subdividing the Primates in Prosimians, Old World Monkeys and New World Monkeys. More widely shared from a scientific point of view appears their distinction in the two suborders of Prosimians and Simians.

However, also in this case not all are in agreement to insert the Tarsiids within the Prosimians and suggest to subdivide the Primates in the suborders of the Strepsirrhines (Strepsirrhini), with their characteristic curved nose, and of the Haplorrhines (Haplorrhini) with the pointed nose; practically, the first ones correspond to the Prosimians without the Tarsiids, and the second to the Simians with the addition of the Tarsiids.

Finally, others besides Prosimians and Simians, recognize also to the Tarsiids the value of suborder. To simplify things, also considering the fact that in the common language, in various texts, even relatively recent, and in the field of the popularization the Primates are still distinguished in Prosimians and Simians, here we shall follow partially the tradition attributing however to Prosimians and Simians a purely descriptive value and not a purely systematic one.

PROSIMIANS (Prosimiae)

As aforementioned, we remind once more that presently the systematic validity attributed to the term Prosimians appears outdated as including groups, like the infraorders, superfamilies and families, that various important characteristics, structural and behavioural, indicate that it is a paraphyletic group where clearly not all parts have originated starting from a common ancestor.

That being said, not deeming this the most suitable location for a phylogenetic discourse about the systematics of the Primates, here below we shall focus on considering the families and the genera classically charged to the Prosimians. Prosimians differ from the Simians, the other group of the Primates, for their general structure of the body that, at least in some families, has maintained characteristics having a greater primitiveness; on the one hand differ from them the Tree shrews, that fairly remind the Insectivores, and on the other the Lemurs and the large Indri that have body and limbs similar to those of the Simians instead to the Prosimians.

Generally speaking, the Prosimians are attributed with species that, in relation to the nocturnal habits, maintain clear connotations of primitiveness such as the big eyes, at times very big, laterally arranged and the sense of smell still well developed. Different from them are the Lemurids of the genus Hapalemur that lead a diurnal life.

Moreover, the muzzle is decidedly pointed, with the rhinary, region of skin surrounding the nostrils commonly known with the name of truffle, humid and equipped with long sensitive vibrissae; this organ, rather than implementing the sense of smell, plays the important rôle of wind direction indicator, thanks to its humid and sensitive surface.

The limbs are of various lengths with thumb and big toe always opposable and the tail is well developed, never prehensile. The body is covered by thick and soft hair.

Fast or slow in the movements depending on the species, the Prosimians are anyway skilled climbers and well adapted to the life on the trees.

The development of the young is fast, the sexual maturity is precocious and often the females generate several sons.

Under the name of Prosimians are united a various number of families, 7-9: Lemurids, Daubentoniids and Indriids exclusive to Madagascar, Tupaiids, Lorisids, Galagids and Tarsiids present also in continental Africa and in south-eastern Asia. It must be clarified once again that several scholars exclude the Tupaiids from the Primates and insert them in the order of the Scandents whilst the Tarsiids, are by some deemed a third suborder of the Primates, others, instead, consider them a family of the Simians and not of Prosimians.

Lemurids (Lemuridae)

The name of the family is clearly referring to the “lemures”, Latin term with which in the Roman mythology were indicated the ghosts of the night; this due to the spirited look of the majority of the species due to the big eyes, well suitable for the night life, and to the emission of sounds resembling painful moans.

They include medium-sized forms and with a weight of about 2 kg, characterized by the long muzzle, of fox-like appearance in the biggest forms and with the lower incisors that, excepting the Tree shrews, form a sort of comb, utilized for the grooming.

The forelimbs are remarkably less developed than the hind ones and have the fingers equipped with nails but the second toe of the feet has a robust claw utilized for the cleaning of the body (grooming). The hands are prehensile with the thumb partially opposable.

The body is covered by a thick fur variously coloured in the different species; the tail is longer than the body and is covered by hair, often plume-like.

Usually gregarious animals, they live in groups formed by many females and several males. They emit very varied screams that have the purpose of contributing to the cohesion of the group and at the same time of informing the members of the group about the approach of a danger.

They have essentially arboreal habits and eat fruits, leaves and flowers and also small animals.

To the family that has been the object of important taxonomic revisions at a generic and also specific level, presently belong about 23 species divided into the genera shortly treated here below.

Common lemurs (Lemur, Eulemur)

The name refers mainly to the species of Lemur and of Eulemur, genera diffused in the forests at low and medium altitude of the Comoros Islands and in Madagascar. They are medium-sized animals that may reach the weight of about 2 kg.

Of mainly diurnal or crepuscular habits and essentially arboreal, these Lemurs are particularly agile and nourish mainly of vegetable substances.

The females deliver usually only one infant who develops rapidly and who, for some months, lives clinging to the abdomen of the mother or perched on her back.

Presently to to the two genera are ascribed altogether a dozen of species, among which are to be remembered the Catta (Lemur catta Linnaeus,1758), animals mainly diurnal and characterized by a splendid tail with white and black rings, the Maky (Eulemur macaco Linnaeus 1766), the Common brown lemur or Brown maky (Eulemur fulvus Geoffroy, 1796) and also the Mongoose lemur (Eulemur mongoz Linnaeus, 1766) and the very rare red-bellied lemur (Eulemur rubriventer Geoffroy, 1850).

Finally, we must not forget that with the name of Sunda flying lemur (Galeopterus variegatus Audebert, 1799) and of Philippine flying lemur (Cynocephalus volans Linnaeus, 1758) are improperly indicated two species that are neither Monkeys and nor Primates. Conversely, these species, known respectively also with the names of Malayan colugo and Philippine colugo, are members of the Dermopterans or Colugos, a very small order of Mammals close to the Insectivores, to which is ascribed only one family. The Colugos are nocturnal animals and are exclusive to the forests of south-eastern Asia.

Microcebus (Microcebus, Allocebus)

Called also Mouse lemurs, they are the smallest members of the family. Arboreal animals and of nocturnal habits, they eat essentially insects and small birds, but also vegetable substances.

The females usually give birth to 1 to 3 infants, after a gestation lasting of about 2 months.

They comprise three species living in Madagascar, among which Microcebus murinus (Miller, 1777) that, as the specific name states, looks like a mouse; the Pygmy mouse lemur (Microcebus myoxinus Peters, 1852), called also Peters’ mouse lemur, is the smallest of the lemurs and of all Primates.

And also, the Hairy-eared dwarf lemur or Hairy-eared mouse lemur (Allocebus trichotis Gunther, 1875), is the only one of the genus and is relegated in the primary forest of the north-eastern territories of Madagascar.

Hapalemurs (Hapalemur)

They stand among the smallest lemurids and distinguish as having a less pointed muzzle with the little developed auricles and the upper incisors placed one behind the other. Also the limbs are short, whilst the tail is long and ruffled.

Diurnal animals, they eat mainly vegetables.

The genus includes the Eastern lesser bamboo lemur of Gray bamboo lemur (Hapalemur griseus Link, 1795), species found in the thickets of bamboo on whose shoots it essentially nourishes and the Broad-nosed bamboo lemur (Hapalemur simus Gray 1871) diffused in the marshy lowlands of the eastern coast of Madagascar.

The females, after a gestation of about 5 months, deliver one particularly developed infant.

Some scholars recognize the Alaotra bamboo lemur, relegated in Madagascar in a restricted area of the riparian vegetation surrounding the lake and till now considered a subspecies of the Eastern lesser bamboo lemur, the value of a distinct species (Hapalemur alaotrensis Rumpler, 1975).

Lepilemurs (Lepilemur)

Commonly called also Weasel lemurs, they are diffused with various forms in all forestal areas of Madagascar.

The genus gathers species that, unlike the other members of the family they belong to, have big ears and well developed eyes, in relation to the nocturnal habits.

Because of these and other characteristics, from various scholars the genus is attributed to a family of its own, that of the Lepilemuridae.

The Weasel lemurs are small animals living on the trees where they go moving with a great agility with rapid jumps facilitated by the exceptionally long hands with opposable thumbs.

Of solitary habits, they nourish of vegetables, essentially of leaves. Two species are known, the Red-tailed weasel lemur (Lepilemur ruficaudatus Grandidier, 1867) and the Weasel sportive lemur (Lepilemur mustelinus Geoffroy, 1851).

Cheirogaleids (Cheirogaleus) 

These are medium-sized Prosimians, more than 60 cm long, tail included, per a weight varying from 200 to 600 grams.

The Cheirogaleids have nocturnal habits and a mixed feeding, animal and vegetal. The females deliver on average 2-3 infants after a gestation of about 70 days.

Of this genus must be remembered the Greater dwarf lemur or Geoffroy’s dwarf lemur (Cheirogaleus major Geoffroy, 1812) of the humid forests of eastern Madagascar, and the Fat-tailed dwarf lemur or Lesser dwarf lemur (Cheirogaleus medius E. Geoffroy, 1812), that is met in the arid forests of western and eastern Madagascar.

Fork-marked lemurs (Phaner)

They are a genus of Prosimians relegated to the coastal rainforest of the peninsula of Masoala, in north-eastern Madagascar. Solitary animals with nocturnal and arboreal habits, the Fork-marked lemurs have small dimensions, reaching a length of the body that usually varies from 22 to 28 cm, per a weight from 300 to 500 g. They nourish essentially of sap and of vegetable resins they extract from the trunks of the plants they incise with the tooth comb; they integrate their diet with insects, larvae and occasionally also with small vertebrates.

The Fork-marked lemurs are easy to recognize due to a typical black stripe on the back that on the top of the head divides like a fork and continues on the sides of the eyes; to this characteristic refers the name of the Eastern fork-marked lemur (Phaner furcifer  De Blainville, 1839), species that some taxonomists divide in several subspecies; of different advice are other taxonomists that recognize to the subspecies of the Eastern fork-marked lemur the status of distinct species with the names of Amber-Mountain fork-marked lemurs (Phaner electromontis Groves and Tattersall, 1991), and Pale or Western fork-marked lemur (Phaner pallescens Groves and Tattersall, 1991) and Pariente’s fork-marked lemur (Phaner parienti Groves e Tattersall, 1991).

Actually, the taxonomic uncertainties of the genus Phaner, as occurs in many other cases in the Primates, are a consequence of the lack of information and of the uncertainty of the diagnostic characters at specific level.

Ruffed lemurs (Varecia)

Called also Ruffed lemurs, they are the biggest members of the family of the Lemurids, reaching a body size of more than 50 cm with a weight exceeding 3,5 kg.

Not all specialists agree about their generic attribution and some of them assign them to the genus Varecia instead of the Lemur.

Two species living in the primary forests of Madagascar have been described, the Black-and-white ruffed lemur (Varecia variegata Kerr, 1792), with its characteristic bicolor fur, black on the belly and on the fore limbs, white on the back and on the hind limbs, and the Red ruffed lemur (Varecia rubra É. Geoffroy, 1812), recognizable because of its red-rust colouration on the upper part of the body. Considered sacred by the Malagasy populations who call them “sons of the sun”, these animals have been an object of worship until a recent past.

Daubentoniids (Daubentonidae)

Presently, the family is represented only by Daubentonia madagascariensis Gmelin, 1788, species known as Aye-aye or Chiromio, from the Greek (from the Greek χείρ “hand” and μῦς “mouse”); exclusive to the forests of Madagascar where it is found in a great variety of natural environments, this Prosimian is found in the primary and secondary rainforest, in the forest broad-leaved trees and also in man-made environments, such as plantations, etc.

Of about the size of a cat, it is 35-45 cm long per an average weight of about 2,5 kg, this lemur has a very particular appearance due to a showy asymmetry of the two hands and a convergence of the general shape of the body that makes it look like a big squirrel; for this characteristic, together with its teeth, with only two incisors on the upper arch and 2 in the inferior, wide and flat, very robust and continuously growing, the Ayé-ayé in the past had been considered as a Rodent. Another anatomical oddity of this singular lemur is the presence of a rough incomplete model of “sixth finger” on each one wrist.

This prosimian has a triangular face, of fox-like appearance, with short snout and pinkish rhinarium; the eyes are relatively small with yellow-orange iris and vertical pupil in relation to the nocturnal habits; the ears are well developed, elliptic, hairless and of black colour. The tail is very long and ends in a plume of hair; the fur is bristly and of brown-blackish colour, that gets paler on the snout and in the lower parts of the body; hands and feet are black.

Depending on the diet formed mostly by insects, the hands, glabrous and with opposable thumbs, present a unique specialization in all Primates; the third finger is extraordinarily thin, long up to three times than the other fingers and is equipped with a long and sharp claw.

This finger together with a very acute sense of hearing reveal fundamental for the purposes of nutrition; the Aye-aye uses this finger for ticking on the bark of the trees and listening to the reverberations through the wood it can perceive any sounds that may reveal the presence of a larva under the woody layer.

Once detected by the noise the presence of prey, the Lemur skins the trunk with its strong incisors until a hole is opened in the tunnel dug by the larva or by the insect; then it utilizes its odd middle finger as an effective tool to skewer and extract larvae and the xylophagous insects it eats.

The diet of this prosimian is completed also with vegetables and eggs of birds.

Nocturnal animal and mainly solitary, the Aye-Aye has the habit of clinging to the branches upside down, like the bats.

Matings do not take place in a precise period, and, after a gestation lasting 150 to 170 days, the female gives birth to only one infant breastfed with breasts. that, a unique feature among primates, are placed in the groin region.

Due to its look this lemur is object of various local superstitions; in many area it is considered as an evil omen and consequently is killed on sight; due to this persecution, aggravated by the removal of natural habitats originated by the deforestation for human settlements, the Aye-aye, like and maybe more than the other lemurs, is seriously threatened with extinction.

Indriids (Indridae)

They form a family of Prosimians of medium-large size, with an essentially herbivorous diet, and of Nocturnal or diurnal habits. Exclusive to Madagascar, the Indriids are subdivided in the genera Avahi, Propithecus and Indri.

In turn, the genus Avahi is divided in the species commonly known as Eastern woolly lemur or Eastern avahi (Avahi laniger Gmelin, 1788) and Western avahi or Western woolly lemur (Avahi occidentalis von Lorenz-Liburnau, 1898); both species are endemic to the humid forests of Madagascar and have nocturnal habits.

The genus Propithecus, includes Lemurs of medium size reaching a length of 45-55 cm and a weight of 4-6 kg; they have a roundish face, hairless and of black colour, the fur is long and silky, the tail is well developed. Animals of diurnal habits, they are common in all rainforests of medium altitude of Madagascar, where they are called with the name of Sifaka coming from the sound they emit.

To the genus are presently ascribed about 8 species, some of them divided in subspecies, distinguishable among them mainly due to the colouration of the fur.

Within the most known species we recall the Diademed sifaka (Propithecus diadema Bennett, 1832), with grey black fur getting white on the back, the Candid sifaka, also called Silky sifaka (Propithecus candidus A. Grandidier, 1871), characterized by an almost completely white fur and the Verreaux’s sifaka (Propithecus verreauxi Grandidier 1867) with its white fur adorned with dark stripes on the side.

Recent taxonomic studies have raised to rank of distinct species the Coquerel’s sifaka (Propithecus coquereli A. Grandidier, 1867) with dorsally grey silver or brown fur and the Von der Decken’s sifaka (Propithecus deckenii A. Grandidier, 1867) with mantle having white-cream hair, with golden, greyish or brown hues, in the dorsal zone, in the past considered as subspecies of Propithecus verreauxi.

Finally, the genus Indri is a very rare Lemur confined, with one only species, the Indri (Indri indri Gmelin, 1788), in the forests of eastern Madagascar.The Indriids are Lemurs that have evolved an almost erect posture and the almost total disappearance of the tail, assuming humanoid forms so much that the Malagasy populations consider them “brothers” of mankind, giving them the name of Bobakoto, that is, sons of the same father. The Indriids are also characterized by having very long hands and feet that allow them to climb and to jump between the branches very quickly; they have diurnal habits and live united in family groups to the cohesion of which they contribute with cries very long and harmoniously modulated that go several kilometres away.

Tupaiids (Tupaiidae)

Due to their general structure that maintains many characteristics of primitiveness of the skeleton, the brain and the teeth, the Tree shrews are defined as the Primates most similar to the Insectivores, and also as the Insectivores most similar to the Primates.

Actually, the Tree shrews form a family of uncertain systematic collocation that some scholars exclude from the Primates and insert, together with the Ptilocercids, in order on its own, that of the Scandents.

The tree shrews are small quadruped animals, similar to shrews, with very short limbs and well developed tail, plum-like. The snout is very long with small and hairless ears: the eyes are placed in lateral position.

They live in the Asian tropical forests where they reach more than 3000 m of altitude. Few species are really arboreal and most of them do have diurnal habits and nourish of fruits and of insects they carry to the mouth with the to hands that are convergent but not prehensile; for what the diet is concerned, are an exception the species of Dendrogaleus living in South-East Asia that seem to eat only insects.

The family is distributed with about one dozen of species united in 4 genera in India and in South-east Asia.

Among the most known species are to be remembered the properly called Tree shrew Tupaia glis Diard, 1820), diffused with more than thirty subspecies in Indochina and in southern China and that owes its specific name to the resemblance to a dormouse, the Large tree shrew (Tupaia tana Raffles, 1821), species living in Borneo and Sumatra and to which are ascribed about 15 subspecies.

Moreover, the Philippines tree shrew or Mindanao tree shrew (Urogaleus everetti, Thomas 1892) of the forests of Mindanao and nearby islands, the Indian tree shrew or Madras tree shrew (Anathana ellioti Waterhouse, 1850) and the Bornean smooth-tailed tree shrew (Dendrogale melanura Thomas, 1892), that lives on the mountains of the northern regions of the Cambodia, Borneo and Sumatra.

The Pen-tailed tree shrew (Ptilocercus lowii Gray, 1848), diffused all over south-eastern Asia, characterizes for the long tail covered by little scales with the extremity provided with a tuft of hairs drooping on two sides, so much to resemble to the feathered base of an arrow: attributed in the past to the Tupaiids, presently this specie is the only member of the family of the Ptilocercids (Ptilocercidae) that together with the Tupaiids form after the opinion of several scholars the order of the Scandents.

Lorisids (Lorisidae)

Commonly called Lorises, they are Prosimians confined in restricted territorial areas of southern Asia, where have differentiated various subspecies in South India and in Sri Lanka, and of Africa.

They are small in dimensions, weigh about 250 g, do not have tails and have short and pointed snouts.

The hind limbs are particularly long.

Hands and feet are prehensile, with opposable thumb and big toe, and characterize for the second finger that is very short or is completely atrophied.

All fingers have nails, but the second toe of the feet, armed with a claw.

The hair of the fur is short and morbid.

Animals with a vaguely spectral look, the Lorisids have nocturnal habits and live on the trees nourishing of insects. Solitary and particularly silent, they emit screeching sounds, utilized especially for the defense of the territory. They are particularly appreciated by the plantation farmers as pets.

Presently, the family is represented by 5 species united in 4 genera, of which we must remember the Sunda slow loris or Greater slow loris (Nycticebus coucang Boddaert, 1785) and the Red slender loris (Loris tardigradus Linnaeus, 1758), species diffused in southern Asia; and again the Calabar angwantibo or Calabar potto (Arctocebus calabarensis Smith, 1860) and the Perodictus potto (Müller, 1766), commonly known under the name of Potto, living in the dense primary forest of Africa.

Galagids (Galagidae)

Commonly known as Galagos and, locally, Bushbabies, they form a family of Prosimians whose members, very skilled jumpers and climbers, are small, variable depending on the species from just under 100 grams to more than 1 kg.

The tail, short and covered by thick and shaggy hair, is used as an important balance organ.

Like in some nocturnal Lemurs, the Galagos have very large and close together eyes. Endowed with excellent hearing, they distinguish as having the pinnae that, besides being conspicuously developed and membranous, are equipped with independent mobility and can be folded in on themselves during sleep.

The hind limbs are longer than the fore ones; the fingers have expanded fingertips forming adhesive pads. Thanks to a high flexibility of the neck, they can rotate the head 180 degrees, like the owls. They are equipped with three pairs of mammary glands placed in pectoral and inguinal position.

Of nocturnal habits, they are arboreal animals and eat essentially insects, other small animals and even fruits.

The family unites about 8 species, of which 6 ascribed to the genus Galago and 2 to Otolemur, that live in the thick forests or in the sparse vegetation areas of tropical Africa. Among the species of Galagids, the most known are the Senegal bushbaby (Galago senegalensis E. Géoffroy, 1796) and the Thick-tailed galago also called Comba or Brown greater galago (Otolemur crassicaudatus E. Géoffroy, 1812).

Tarsids orTarsiids (Tarsiidae)

They owe their name to the characteristic, unique in the mammals, of having the hind limbs elongated due to the remarkable development of the tarsal, instead of metatarsal, bones.

They form a group of doubtful systematic position; in fact, with the name of Tarsioids, some scholars consider them a suborder of the Primate, distinct from Prosimians and Simians, conversely, others place them among the last ones, because of the presence of anatomical characters of phylogenetic importance, in particular the complete frontalization of the eyes and the absence of the rhinarium.

They gather forms, with the size of a big mouse, with a weight averagely included between 80 and 150 g with rounded head and big and globular eyes; the pinnae are variously developed, at times large, without hairs and quite mobile.

All fingers, long and with swollen fingertips, are provided with flat nails but the second and third toe of the feet where the nails are similar to small claws, utilized for grooming the body.

The thumb is little opposable whilst the big toe is fully such. The tail is very long and thin, without hairs except a plume on the tip.

Arboreal animals endowed with an extraordinary agility, presently the Tarsiids are confined in the forests of medium and low altitude of South East Asia where they represent a remnant in the past diffused also in Europe and in North America.

Endowed with exceptionally sharp sight and hearing, they have crepuscular or nocturnal habits and mainly nourish of invertebrates, like insects and spiders, and small vertebrate reptiles, like frogs and lizards.

The females, after an about 6 months long gestation, deliver only one son, who after a few hours is already capable of clinging and climbing.

Until recently, to the family was uniquely attributed the genus Tarsius, with the species: the Spectral tarsier (Tarsius tarsier Erxleben, 1777), where converges as synonym the Tarsius spectrum (Pallas, 1779), the Philippine tarsier (Tarsius syrichta) and the Western tarsier (Tarsius bancanus).

However, recently, also the genus Tarsius has been object of revision and nowadays the Philippine tarsier has been reclassified as Carlito syrichta ( Linaeus, 1758), only species of the genus Carlito, whilst the Western tarsius is attributed to the genus Cephalopachus with the specific name of Cephalopachus bancanus (Horsfield, 1821).

This species, divided in three subspecies, as well as in the islands of Borneo and of Sumatra, lives also in numerous surrounding small islands.

SIMIANS  (Simiiformes)

Called also Anthropoids or Higher primates, they form a group, more homogeneous than the Prosimians and from which they differ due all a series of anatomic and behavioural peculiarities where the evolutionary characteristics of the Primates reach the most typical and complete expressions. In particular, in the Simians the complete straightening of the trunk affirms, the reduction of the sense of smell, the anterior position of the eyes with the improvement of the stereoscopic and colour vision, the development of the brain that gets more structured and heavier than the body weight; in parallel, the intellectual and manipulative skills develop to reach, especially in orangutans, chimpanzees and consequently in the man the highest levels known in the animal world.

Are concerned species of dimensions included between those of a squirrel like the Marmosets and the Tamarins, of the family of the Cebids to those of the eastern gorilla, Gorilla gorilla, of the family of the Hominids, that can reach, and even exceed, 180 cm of height and weigh averagely 150-180 kg.

The Simians have often a rounded head, with the muzzle of very variable conformation, from short to very protruding. The face is more or less without hairiness and in some species is surrounded by a beard. The rhinarium and the vibrissae are replaced by a nose with more or less close nostrils; typically, the ears have the pinna not too developed.

In most species, hands and feet are prehensile with thumb and big toe usually opposable. The body is covered by pilosity less thick than in the Prosimians; the skin is richly pigmented and in the glabrous zones of the face, of the genital region and of the buttocks may get conspicuously coloured shades, as we can see in the Mandrill (Mandrilus sphinx Linneus,1758).

The Simians are equipped with real and proper sudoriferous glands and a pair of mammary glands located in the pectoral region, depending on the more or less erect posture of the body.

In some, colugo and gibbons, are present ischial callosities, characteristic pelvic pads that allow these animals to sleep in erect position on thin branches, without falling and out of reach of predators.

In relation to the type of movement, the fore and hind limbs have equal or different length.

The tail can be of varying length or even absent as is the case in the Hominids; it is prehensile only in some species of the American continent.

The Simians are subdivided in two groups that it is believed to have originated starting from a same progenitor and that have undergone a different evolutionary story due to their isolation following the separation of the South American continent from the African one caused by the continental drift.

The long isolation, begun in the Oligocene and lasted about 40 million of years, has led to the present differentiation of the monkeys of South America from those of Africa; this reason stands at the base of the distinction between Simians of the New World (Platyrrhines) and Simians of the Old World (Catarrhines) to whom some scholars recognize the systematic status of infraorders.

Platyrrhines (Platyrrhini)

The Platyrrhine Monkeys, or New World Monkeys, represent an evolutionary branch that has differentiated in South America where they remained isolated from the African Monkeys due to the separation of the African continent from South America; the long isolation undergone, about 40 million years, has oriented to two different evolutionary paths the South American Monkeys and the African ones leading to the diversification of Platyrrhines and Catarrhines.

Nowadays the Platyrrhines are represented by species that, as the name indicates, distinguish from the Catarrhines as having a wide and flat nose with distant nostrils and facing sideways.

They are animals of small and medium size, varying from 20-30 cm of total length per a weight of about 100 g of the Pygmy marmoset (Callithrix pygmaea Spix, 1823)to reach and even exceed the metre of length and the weight of 10 kg in the howler monkeys of the genus Alouatta and in the woolly monkeys (Lagothrix).

Of mainly diurnal habits and very well adapted to the arboreal life of the tropical forest, these Monkeys have long arms and thumbs not opposable to the other fingers.

The tail can be long and endowed with prehensility like in the family of the Cebids, or of smaller dimensions with tufted apex similar to that of the squirrels, like in the family of the Callitrichids.

Among the less evolved Monkeys, unlike the Catarrhines, the Platyrrhines have no cheek pockets and ischial callosities and, with the exception of the howler monkeys (Alouatta), also lack colour vision. The mouth has 12 premolars, whilst the Catarrhine Monkeys have 8 of them.

The Platyrrhines lead almost exclusively an arboreal life and have habits mainly diurnal; are an exception the members of the family of the Aotids, that lead a nocturnal life.

The diet of the Platyrrhine Monkeys is essentially omnivorous, with the prevalence of vegetable or animal material.

Usually they form stable monogamous couples and the parental cares of the infants are rightly entrusted to the male, whilst the female practically limits to the breastfeeding.

The systematics of the Platyrrhines, to whom until recently was ascribed the unique superfamily of the Ceboidea, in turn divided in the family of the Cebids and in that of the Callitrichids, has been discussed by the recent classification based on the comparison of the mitochondrial DNA that has evidenced the existence of more or less close affinities between the various families.

Considering the review of the Platyrrhines is not yet clearly defined, here we consider it appropriate to limit ourselves proposing the subdivision of the New World monkeys in the families of the Cebids, Aotids, Atelids and Pithecids.

Cebids (Cebidae)

They include small and medium sized monkeys, included between 20-30 cm of total length per a weight of about 100 g of the Pygmy marmoset (Callithrix pygmaea Spix, 1823) and the about 80 cm per a weight of 4 kg of the Crested capuchin (Sapajus robustus Kuhl, 1820).

These are Monkeys of arboreal and diurnal habits, being omnivorous, nourishing of vegetable material (leaves, flowers, buds, fruit, sap) and also animals (insects, eggs and small vertebrates).

To this family are ascribed the Monkeys diffused in Central and South America, known with the common names of Marmosets, Tamarins, Squirrel monkeys or Saimiris and Capuchin monkeys.

Social animals, they live in groups of variable dimensions depending on the species.

The females have a gestation lasting 90-120 days, at the end of which they usually deliver only one infant or two twins.

The present classification ascribes to the family 7 genera where are united more than 50 species, of which, here below, we provide essential information.

Callimico

It is a genus that includes only one species, commonly known with the names of Goeldi’s marmoset or Goeldi’s monkey or Callimico (Callimico göeldii Thomas, 1904), living in the thick undergrowth of the Amazonian forest of Brazil, Colombia, Ecuador, Peru and Bolivia.

The Callimico is a monkey that can be about 50 cm long, half of which concern the tail, per a weight of about 600 g.

The muzzle, the hands and the feet are black, the fur is dark brown or black with white spots and a sort of caparison of hair longer on the neck and on the shoulders. All nails are pointed, but that of the thumb, which is wide and flat.

Diurnal animals, they live in groups made of 5-6 individuals, that keep in touch thanks to a series of high-pitched calls, often even ultrasounds not perceptible to the human ear.

Highly agile, the Callimico owes also the name of Jumping tamarin due to the fact that it moves from one branch to another by means of leaps that can exceed 4 m.

The diet is formed mainly by fruits, insects, small vertebrates and, during the dry season, also by various species of edible mushrooms.

The females, after a gestation that averagely lasts about 100 days, give birth to only one infant, who is cared for by both parents.

Callithrix

It is a genus that unites species diffused in the pluvial forest of South America commonly known with the names of Marmosets. They are Monkeys that, compared to the other Platyrrhines, maintain numerous characteristics of primitiveness, such as nails similar to claws, presence of vibrissae and absence of the third molar (wisdom teeth).

In the genus are included species of small size, averagely about forty centimetres long, or even less, including the tail, longer than the body and not prehensile.

Very active animals, the Marmosets eat mainly fruits and insects; conversely, some species nourish essentially of sap and gum resin they make pour from the trees carving their bark with their very sharp lower incisors; in particular the White-tufted marmoset (Callithrix jacchus Linnaeus 1758) and the Pygmy marmoset (Callithrix pygmaea Spix, 1823) are considered obligate resinivores.

Arboreal animals, the Marmosets live usually on top of the great trees among whose branches they move with a lot of agility on the four limbs and utilizing the tail for balance. They form family groups counting three to fifteen elements. In most species the female delivers two infants that are cared for by all members of the group.

From the taxonomic point of view the situation of the genus is not yet well defined as presently some scholars merge into Callithrix,, degrading them to the rank of subgenera, Cebuella, Calibella, Mico that, conversely, other scholar continue to consider as many distinct genera.

Anyway, regardless of different opinions, we can say that to the group Callithrix affer about twenty species among which well known stand the White-tufted marmoset (Callithrix jacchus),, once diffused all over eastern Brazil, now confined in the Atlantic forest of the south-eatsern zone, the Pygmy marmoset (Callithrix pygmaea or Calibella pygmaea) living in the high basin of the Amazon River and the Silvery marmoset (Callithrix argentata or Mico argentatus) found in the rainforests habitats of the south-eastern Amazonian basin.

Leontopithecus (=Leontocebus)

It is a genus in which are united species living in the Brazilian forest of the Atlantic side where they live relegated to restricted ranges and with rather small populations. Referring to the leonine look due to the tufts of erectile hair on the sides of the face, similar to the mane of a lion (from the Greek “lion monkey”), are indicated with the collective noun of Leontocebes, but also of Lion monkeys or Maned marmosets.

They are monkeys whose dimensions are close to 40 cm per a weight of less than 1 kg.

Of diurnal and arboreal habits, they have an omnivorous diet as they mainly eat insects and their larvae, that they drive out scratching in the rotten wood with their sharp nails, but also small vertebrates and fruits.

They live merged in small family groups; the females generate a couple of infants cared for by both parents.

To the genus are attributed four species distinguishable from each other due to the different colouration of the fur, among which the great Golden lion tamarin or Golden marmoset (Leontopithecus rosalia Linnaeus, 1766), of the Brazilian forests, now seriously threatened with extinction.

Saguinus

Other genus where are grouped species of Cebids that distinguish from the other Platyrrhines, besides the small dimensions, included between 20 and 40 cm, tail excluded, per a weight of 400-800 g, also for having the fingers armed with nails modified in claws.

Commonly indicated also with the name of Tamarins, these Monkeys characterize for the presence of long facial hairs shaped like a beard and moustache that is of black or brown colour, paler or white on the ventral part.

Of diurnal habits, these Tamarins are frugivorous and insectivorous animals.

They live in more or less numerous groups in forestal environments of Central and South America.

The social organization of these Platyrrhines is typical for the tendency to form stable reproductive couples.

The females frequently give birth to two infants that are cared for especially by the father, whilst the mother mainly provides for their breastfeeding.

After various taxonomic revisions, presently to the genus Saguinus are ascribed a little less twenty species, the most known of them being the White-lipped tamarin (Saguinus labiatus Géoffroy, 1812), the Emperor tamarin (Saguinus imperator Goeldi, 1907), and the Brown-mantled tamarin (Saguinus fuscicollis Spix, 1823).

Cebus

Genus of Cebid where are ascribed Platyrrhine Monkeys of medium size, 110 cm of maximum length per a weight of about 6 kg, with the tail as long as the rest of the body, not prehensile and often arranged curly or arched with the curl facing down.

Diffused from Honduras to Paraguay and northern Argentina, the species of this genus are commonly known with the collective name of Cebides (from the Greek Kébos, “monkey with the long tail”) or Capuchins due to the colouration of the mantle that reminds the habit of a Franciscan monk.

All the species of this genus have diurnal and arboreal habits, the diet is mainly based on fruits and seeds, integrated with birds and their eggs, insects and small vertebrates.

The Capuchins live in more or less numerous groups, formed by 6-40 members, and have social habits extraordinarily similar to those of the Monkeys of the Old World (Catarrhines). This probably represents a case of evolutionary convergence due to similar lifestyles on both continents.

Usually, the females reproduce every two years and, after about six months of gestation, give birth to only one infant that initially they carry attached to the chest.

Considered as standing among the most intelligent in the Platyrrhines, the Capuchins are able to utilize tools, such as stones and pieces of wood, for breaking the shells of the seeds or other material they eat.

Among the 14 species presently attributed to the genus are to be mentioned: the Ecuadorian capuchin (Cebus aequatorialis Allen, 1914), that populates the forestal environments of the Pacific coast of Ecuador, the Humboldt’s white-fronted capuchin (Cebus albifrons Humboldt, 1812) that lives in the primary and secondary rainforests of the north-western South American regions, the Colombian white-faced capuchin (Cebus albifrons Humboldt, 1812) that occupies a vast range going from Honduras to central-western Brazil and the Varied white-fronted capuchin (Cebus versicolor Pucheran, 1845), species diffused in Colombia.

Saimiri

It is a genus diffused in the tropical forest of Central and South America. It unites species known under various names, such as Squirrel monkeys, Saimiri and Chrysotrix (golden hair); they are also called Death’s head monkey due to the particular look determined by the colouration of the face, presenting black muzzle and eyes with a characteristic small white mask around the eyes.

The dimensions of the Saimiri vary from 60 to 75 cm per a weight between 800 and 1200 g; the tail is usually longer than the body and is used as compensator during their movements among the branches.

Typically, the females have one pseudopenis that they display as tool of intimidation in the manifestations of dominance.

With diurnal and arboreal habits, the Saimiri live in groups usually very numerous, including males and females in a variable proportion.

Omnivorous animals, they mainly feed on fruit and insects and, occasionally, also on small vertebrates.

They reproduce on a seasonal basis in such a way that after about five months of pregnancy, the birth of the only one infant may happen during the season of the rains; the female is the only one to take care of the baby.

Presently to the genus are ascribed five species distinguishable from each other on the base of the shape of the small mask around the eyes, among which the Saimori, known as Chrysothrix or Squirrel monkey (Saimiri sciureus Linnaeus, 1758), diffused in most tropical South America, from Venezuela to northern Argentina, and the Central America squirrel monkey (Saimiri oerstedii Reinhardt, 1872) that lives on the Pacific side of Central America.

Sapajus

It is a genus of Cebids whose members have a look quite similar to the capuchin monkeys of the genus Cebus from which are distinguished especially for the more robust size; actually the taxonomical validity of the genus is still to be defined in its distinctive characteristics.

Presently Sapajus is divided in 7-8 species among which we remember the Tufted capuchin (Sapajus apella Linnaeus 1758), known also as Brown capuchin, Black-capped capuchin or Pin monkey, amply diffused in the Amazonian basin, the Blond capuchin or Golden capuchin (Sapajus flavius Schreber, 1774) that lives in the coastal areas of north-eastern Brazil; and again the Black-striped capuchin or Bearded capuchin (Sapajus libidinosus Spix, 1923) that divided in various subspecies is diffused in the central-eastern territories of South America.

Other species of the genus are the Large-headed capuchin Sapajus macrocephalus Spix, 1823) found in the rainforest of the piedmont zone east to Andes, the Black capuchin (Sapajus nigritus Goldfuss, 1809) of the south-eastern Brazil and northern Argentina and the Crested capuchin (Sapajus robustus Kuhl, 1820), species endemic to the territories of Atlantic forest of south-eastern Brazil.

Finally, the Golden-bellied capuchin or Buff-headed capuchin (Sapajus xanthosternos Wied, 1826) is presently confined in the south-eastern territories of the Brazilian state of Bahia.

Aotids (Aotidae)

The members of this family are so called, from the Latin without ears, due to the fact that at first sight, they seem to be without pinna that, instead, is very reduced and hidden by the hairs.

Other names under which are commonly known these Platyrrhine monkeys are those of Night monkeys, Aoti, Owl monkeys, Douroucoulis, Nittipithecus.

The Aotids form a family of Platyrrhines with rather primitive characteristics, diffused in Central and South America, between Panama and the northernmost territories of Argentina.

They are Monkeys of modest size, usually with of variable length from 25 cm to over less than 50 cm and with the tail about one and a half times the length of the body, the eyes are very big, in relation to the habits of night animals. The colour of the fur is very various, depending on the geographic position. Arboreal animals, the Aotids live in the rainforests and in the savannah or in their proximity where they eat essentially fruits, leaves and insects.

They reproduce once a year and the female delivers only one infant that initially is cared by the mother and later by the father. They live in small family groups and usually form stable couples.

The family includes only the genus Aotus to which presently some Authors attribute about ten species; but, also in this case, there is no agreement as some tend to maintain the old classification, considering all others only local varieties, other instead recognize specific validity only to the Three-striped night monkey or Northern owl monkey

(Aotus trivirgatus Humboldt, 1811), that lives in the warm rainforests of Venezuela and of the central-northern territories of Brazil, and to the Azara’s night monkey (Aotus azarae Humboldt, 1811) that is found in the central area of South America.

Atelids (Atelidae)

They are a family of Platyrrhine Monkeys whose members live in Central and South America.

They are animals whose dimensions, depending on the species, vary from 35 cm of some Spider monkeys (Ateles) to the more than 90 cm of the Howler monkeys (Alouatta) and of those of the genus Brachyteles.

The Atelids unite species equipped with long prehensile tails they utilize as if they were a fifth limb for a better grip on the branches.

The first two fingers of the hands are opposable to the remaining three.

Most species have diurnal habits and usually live on the trees of the rainforest but are found also in the wooded savannah.

They eat mainly leaves and fruits, and also insects.

Polygamous animals, the Atelids live usually merged in numerous groups, composed by twenty and more adults.

Frequently, a single male tends to impose itself and drive out the others, forming a harem.

The females, after a gestation of 6-7 months, deliver only one infant.

Presently to the family are ascribed totally about 25 species distributed in the genera Alouatta, Ateles, Brachyteles, Lagothrix and Oreonax.

Alouatta

It is a genus of Atelids whose species populate the rainforests of Central and South America. They are Platyrrhines whose dimensions vary depending on the species from 50 to 90 cm per a weight exceeding 10 gg; the tail as long as the rest of the body, is prehensile.

The habit of utilizing a lot the vocal communication that is particularly strong, has deserved the species of the genus the name of howler monkeys. This characteristic is linked to the presence of a hyoid bone conformed in a particular way that allows them to emit particular sounds, similar to roars in males and grunts in females, that have the function of demarcation and of claim of the territory. Amplified by the enlarged and sacciform larynx, the calls of the Howler monkeys can be heard up to more than 5 km of distance.

Of diurnal habits, unlike other Platyrrhines the species of the genus have a colour vision.

The Howler monkeys nourish exclusively of vegetables, mainly leaves.

Rather slow animals in the movements, they spend good part of their time in a state of complete inactivity.

To the genus are attributed about ten species among which the Black howler (Alouatta caraya Humboldt, 1812) that lives in the rainforest of Brazil, Bolivia, Paraguay and north Argentina, the Mantled howler (Alouatta palliata Gray, 1849), with the hair uniformly black and diffused in the forest environments between southern Mexico and western Ecuador, the Guatemalan black howler (Alouatta pigra Lawrence,1933) of south-eastern Mexico and the Red-handed howler (Alouatta belzebul Linnaeus,1766) of northern and eastern Brazil.

Moreover, we have not to forget the Colombian red howler (Alouatta seniculus  Linaeus, 1766) that, divided in various species, lives in the swamps of mangroves and in the tropical forests of the northern territories of South America.

Ateles

It is a genus of Atelid monkeys to which are ascribed species that characterize for the particularly long legs, the fore ones longer than the hind ones; the hands have the thumb not opposable and 4 long fingers and curved like a hook; the feet have 5 toes.

Commonly known as Ateles or, referring to the look, also Spider monkeys, species of the genus characterize for having rather small and nostril very spaced from each other.

Averagely, the dimensions reach 70 cm of length, per a weight around the 6 kg. The tail, even up to 90 cm long, prehensile and particularly strong, is utilized as fifth limb for moving between the branches and as balancer when moving on the ground.

Diffused in the primary rainforest of Central and South America, the Spider monkeys live united in groups of 15-25 individuals directed by a dominant female. Among the most intelligent of the order, unlike the Howler monkeys, the Spider monkeys communicate with each other assuming different postures, rather than through vocalizations.

Presently there is still not an identity of views about the specific repartition of the genus; some scholars ascribe to Ateles 7 species among which the White-bellied spider monkey (Ateles belzebuth Géoffroy, 1806) that lives in the rainforests of northern Amazonia, and the Geoffroy’s spider monkey (Ateles geoffroyi Kuhl, 1820), whose range extends from Mexico up to part of Colombia.

Brachyteles

Commonly indicated with the names of Woolly spider monkeys, or Muriquis, referring to the remarkable size, term with which locally are indicated the biggest monkeys, the members of this genus live confined in the forest of the Atlantic side of Brazil.

They differ from the Spider monkeys of the genus Ateles, to which they were initially ascribed as only species (Ateles arachnoides E. Geoffroy, 1806) due to the bigger size and the more prominent belly; furthermore both sexes have large genitals and in the males the penis is provided of a penis bone (baculum), unlike the Spider monkeys that do not have it.

Diurnal animals and essentially arboreal, the Muriquis eat vegetable substances, mainly leaves, and fruits.

They live in groups, formed by a variable number of males and females. The gestation lasts averagely 8 months at the end of which is delivered only one infant that is cared mainly by the females.

When about two years old, weaning occurred, the male sons remain in the group, whilst the females go away looking for a new group.

To the genus are ascribed two species, both endemic, the Southern muriqui Brachyteles arachnoides (E. Géoffroy,1806), locally called also Charcoal monkey due to the face of soot-black colour, and the Northern muriqui Brachyteles arachnoides (E. Geoffroy,1806), species relegated in restricted territorial areas and nowadays deemed to be one of the most rare and mostly threatened monkeys.

Lagothrix

It forms a genus that include the so-called Woolly monkeys or Lagotrici diffused in the rainforests of South America.

Like the species of the genus Oreonax, these Monkeys due the name to the thick and woolly fur whose colour, usually dark, varies from reddish to brown, to grey. Typically, the superciliary arches are very prominent.

They averagely measure 120 cm of length, per a maximum weight of about 10 kg; the tail is long and prehensile and is utilized as fifth limb for moving between the tops of the trees.

The Woolly monkeys in groups formed by various family units; diurnal animals and mainly arboreal, have essentially frugivorous habits, but eat also seeds and leaves, insects and small vertebrates. Nowadays the genus unites five species, in the past deemed as subspecies of Lagothrix lagotricha, distinguishable from each other especially for the colour of the fur.

The Brown woolly monkey (Lagothrix lagotricha Humboldt, 1812) that lives in the primary rainforest where it goes up to an altitude of 3000 m of northern South America, the Colombian woolly monkey (Lagothrix lugens Elliot,1907), that populates the middle river course of the Rio Magdalena in Colombia and in Venezuela, and the Silvery woolly monkey (Lagothrix poeppigii Schinz, 1844) that loves the zones of primary rainforest, at altitudes reaching 3000 m in the zone of boundary between Brazil Ecuador and Peru.

Oreonax

It is a genus presently represented only by the Yellow-tailed woolly monkey (Oreonax flavicauda Humboldt, 1812)) species endemic to a small area of rainforest of the Andes of Peru.

Yore classified as Lagothrix flavicauda, this animal owes its own specific name to the presence of a wide yellow band on the terminal part of the tail.

50-70 cm long, with a weight that may exceed and endowed of a 60-70 cm long prehensile tail, the Woolly monkey owes its own vulgar name to the thick and woolly fur, of red-brownish colour, that protects her from the rigid temperatures of its mountain habitat.

The face is glabrous and of black colour, with the exception of a whitish spot around the mouth.

Arboreal and diurnal animal, it eats mainly fruits, flowers, buds and leaves.

It lives in small groups of 4-13 individuals.

Of polygamous habits, the females of this species deliver only one small infant every one-two years.

Pitheciids (Pitheciidae)

Currently raised to the rank of family, the Pitheciids have diffused in South America with more than forty species, commonly known with the names of Uakaris, Pithecia, Titis and Bearded sakis.

They are medium-small sized Monkeys, with the body of dimensions included from 20 cm of Callicebus to 50 cm of Cacajao. The tail, usually as long as the body, is not prehensile.

Of diurnal and arboreal habits, they nourish mainly of vegetable substances, such as fruits, leaves, seeds and buds, but also of small arthropods. They live merged in groups of various dimensions depending on the species. All members of the family deliver only one infant at the time.

The subdivision of the Pitheciids in genera, species and subspecies has been object of various revisions also after expeditions in unexplored territories or poorly known of the Amazonian basin that have led to the discovery of new species.

Callicebus

To the genus Callicebus are ascribed the species, presently more than thirty, commonly indicated with the name of Callicebus or Titis diffused mostly in the Amazonian rainforest of southern Colombia, Peru, Brazil and northern Paraguay.

They are Monkeys of medium size whose length stands between 50 and 90 cm, per a weight of about one kilo.

The tail, partially prehensile, is longer than the body and is covered by hair.

The Callicebus have diurnal and arboreal habits and prefer the environments of thick forest close to water streams.

Particularly agile and active, they utilize the hind legs, slightly longer than the fore ones, to jump from branch to branch, hence the name of Jumping monkeys.

They eat vegetables, essentially ripe fruits, and also animals, like insects and other arthropods and small vertebrates and their eggs.

Usually they form monogamous and stable couples.

After a gestation of about five months, the females give birth only to one infant, quite rarely two, cared mainly by the father.

After following revisions, presently to the genus Callicebus are ascribed more than 30 species in turn divided in two subgenera (Callicebus and Torquatus) and in five groups (clades).

Most species are exclusive to more or less restricted ranges.

Here below we mention the most known species.

The Coppery titi (Callicebus cupreus Spix, 1823), lives in Peru in areas of rather dense forest close to permanent sources of water, the Dusky titi or Red-bellied titi (Callicebus moloch Hoffmannsegg, 1807), diffused in a quite vast area south to the mouths of the Rio of the Amazon, the Bolivian titi or the White-eared titi (Callicebus donacophilus d’Orbigny, 1836), is found in eastern Bolivia, central-southern Brazil and in the northernmost territories of Paraguay.

Other species of the genus are the Collared titi (Callicebus torquatus Hoffmannsegg, 1807) that occupies the area of Amazonan forest at the boundary between Brazil and Colombia and the Monkey of the Golden Palace (Callicebus aureipalatii Wallace, 2005), species exclusive to the Madidi National Park, in Bolivia.

Cacajao

Other genus of the family is Cacajao that groups species living in the high Amazon basin, on the two banks of the Rio Japurá, and that, unique case among the Platyrrhines, characterize for having a very short tail, just about ten centimetres long.

Known under the collective common name of Uakari, these monkeys, that measure about 50 cm, distinguish for having the face without hairs up to the top of the skull and to the temple that recalls the image of a human skull.

The mouth has particularly long and pointed inferior incisors.

Apparently clumsy animals, the Uakari are very agile and active monkeys, capable to leap six metres in length.

Social animals, they form colonies that can count up to one hundred individuals.

They nourish of fruits, seeds, leaves and buds.

To the genus are presently ascribed the Aracá Uakari (Cacajao ayresi Boubli, 2008), species recently discovered in Brazil in the basin of the Rio Aracá, tributary of the Rio Negro, the Bald uakari (Cacajao calvus Géoffroy, 1847), reported in the rainforest areas north to the Amazon River between western Brazil and Peru, and the Black- headed uakari (Cacajao melanocephalus Humboldt, 1812) diffused in the flooded forest of the Rio Negro basin, between Colombia and Venezuela.

Finally, at the genus is to be duly added a fourth species, the Neblina uakari (Cacajao hosomi Boubli, 2008), presently reported for the Pico da Neblina, at the boundary between Brazil and Venezuela but with insufficient distinctive indications.

Pithecia

It is a genus to which are ascribed the Monkeys known with the collective name of Pithecias or Sakis that live in South America, from southern Colombia up to northern Bolivia.

To the Pithecias are attributed species that reach the dimensions of one metre, with not prehensile tail and as long as the body. Arboreal and diurnal animals, they nourish mainly of fruits, but also of flowers, leaves, insects, and occasionally also of small vertebrates.

They live in family groups formed by strictly monogamous couples with their infants. After six months of gestation, the females deliver only one son. Presently to genus are assigned the following five species.

The White-faced saki or Guianan saki (Pithecia pithecia Linnaeus, 1766), so called because of its white fur that surrounds the face of the male, is a species that may be found in the rainforests of plain and mountain north to the Amazon River.

The Equatorial saki or Red-bearded saki (Pithecia aequatorialis Hershkovitz, 1987), that owes its common name to the reddish colour of the males’ little beard, lives in the rainforest of the eastern piedmont belt of the Andes, from Ecuador and Peru.

The White Pithecia or White-footed saki (Pithecia albicans Gray, 1860), so called due to the white pinkish colour of the hands, is a species confined in a restricted area of rainforest south to the Amazon River.

The Gray’s bald-faced saki (Pithecia irrorata Gray, 1845), whose name refers to the presence of a white spot on the skullcap, populates the areas of the primary rainforest of the zone of boundary between northern Bolivia and central-western Brazil.

The Monk saki (Pithecia monachus Geoffroy, 1812), characterized by a mantle with long and bristly hairs of brown-blackish colour and grizzles on front and on the sides of the skull, is found in the rainforest, east to the Andes.

Catarrhines (Catarrhini)

Known also as Old World monkeys because native to Africa, and present also in Asia and on the Rock of Gibraltar in the extreme part of Europe, these Primates owe their own name to the characteristic of having the nasal septum narrow with the nostrils close together and more or less open downwards. These are Monkeys of dimensions averagely bigger than those of Platyrrhines, at times even very big as is the case of the anthropomorphous families Hylobatids and Hominids.

As previously said, the Catarrhines represent an evolutionary branch whose differentiation from the other branch, the Platyrrhine’s one, had its beginning in the Oligocene, after the separation of Africa from South America and their spacing adrift towards their present positions.

Most species of the Catarrhines are endowed with big fat pads on the buttocks that allow them to sit and sleep on the thin branches in an erect position without falling; the tail if present, is never prehensile. The thumb is always opposable. Essentially arboreal animals, apart the members of the family of the Hominids they are excellent climbers.

The present distribution of the Catarrhines includes the tropical belt of Africa and of Asia, though some species move to more northern latitudes, as is the case of the Japanese macaque, or Snow monkey (Macaca fuscata Blith, 1875) that is found in almost all the Japanese archipelago, or at considerable altitudes, like the Tibetan macaque (Macaca thibetana Milne-Edwards, 1870) that, diffused in southern China, reaches the Tibetan plateau. In the group of the Catarrhines are included 3 families, Cercopithecids, Hylobatids, Hominids, but also in this case there is not identity of views among the scholars.

Cercopithecids (Cercopithecidae)

They form the most numerous family of Catarrhine Monkeys and unite species equipped with a usually long tail, but that is short in the Macaques and absent in the Barbary ape; in any case the tail is never prehensile.

They are animals of variable length, averagely from 30 to up a little more than 100 cm, with rounded head and face without hairs; the muzzle is more or less prominent, the nose is usually flattened and with close nostrils, the mouth has 32 teeth.

Of mainly arboreal habits, the Cercopithecids have the fore legs shorter than the rear ones, excepting the species leading a terrestrial life, with the hands shorter than the feet and with flat nails, in some case keeled.

Usually, the fur is inconspicuous, of colour varying from the dark green to brown to grey; in some species it may have even lively and bright colours.

Gregarious animals, usually they live merged in polygamous family groups, but occasionally they aggregate in even very numerous gangs.

The females deliver 1-2 babies after a gestation whose duration, depending on the species, varies from 140 to 210 days, up to 270 days like in the mandrill.

The Cercopithecids have essentially omnivorous habits, with several species that display strong prevalence or exclusivity for foods of plant origin.

The family unites about 60 species grouped in 23 genera, that for the most part live in the large tropical forests; some species do live in the savannahs and in rocky environments, few ones also go into mountainous areas.

Considered the high number of members of the family, here we shall limit our attention to the genera that include the species most known or of particular interest.

Cercopithecus

Commonly known with the collective name of Cercopithecs, the species of this genus are exclusive to Africa south of Sahara where they live mainly in the forests; some species is met also in the savannah. They are Monkeys of dimensions standing between 30 and 70 cm, with a weight that may reach the weight of 10 kg and with round head. Essentially arboreal, but also terricolous, the Cercopithecs have diurnal activity and nourish mainly of fruits and other vegetables, but also of eggs, insects and small vertebrates.

They are territorial and gregarious animals and live in family groups formed usually by 10 to 30 individuals, but that sometimes may reach even the 200 members. Presently for the genus have been described about 22 species distinguishable from each other for the chromatic model of the fur; however it must be kept in mind that for some of them the status of species is somewhat questionable.

Among the most representative species we recall the following: the White-throated monkey (Cecopithecus albogularis Sykes, 1831) is present in forestal habitats of eastern and southern Africa east to the Rift Valley; the Silver monkey (Cercopithecus doggetti Pocock, 1907), diffused in the eastern part of Congo, southern Uganda and north-western Tanzania, the Diademed monkey (Cercopithecus mitis Wolf, 1822), sporadically diffused in zones of central Africa in habitats characterized by the presence of trees and by the proximity of water.

And again, the Mona monkey (Cercopithecus mona Schreber, 1774), diffused in an ample range extending in western Africa in forest habitats, the De Brazza’s monkey (Cercopithecus neglectus Schlegel, 1876), species present in habitats of rainforest of central Africa and the Crowned monkey (Cercopithecus pogonias Bennett, 1833), that lives in the tropical rainforest of central and western Africa.

Chlorocebus

Genus of the family whose members, indicated with the collective name of Cercopithecs as well as all species of Cercopithecus, are more specifically known as Green monkeys, in reference to the colour of the back of the fur where the green colour is prevailing. It includes monkeys of medium size, with the males measuring about 40 cm of length per a weight just exceeding 4 kg, whilst the females are slightly smaller, usually about 35 cm long and weigh about 3 kg.

The tail is as long as the rest of the body. On the front is present a characteristic white stripe more or less ample. The fur, formed by not too long hairs, on the back is of variable colour depending on the species, from grey-greenish to pale yellow, up to dark brown; the ventral parts and the beard, variously developed, and the mustaches are cream yellow. The muzzle, hands and feet have no hairs and are of black colour. The males have a typical bright blue colouration of the scrotum that contrasts with the lively red colour of the penis.

Mainly terricolous animals and of diurnal habits, these monkeys are more active during the first hours of the morning and in the late afternoon, whilst they dedicate the warmest hours of the day to the rest and to the grooming; in the evening, they climb the trees for the night rest. Their diet is substantially omnivorous, formed mostly by fruits and other vegetable substances completed also by insects and small vertebrates.

They are social monkeys living in groups organized following a rigid hierarchical structure where the dominant individuals play a privileged rôle especially for what the fruition of the food is concerned; each group is formed by a various number of individuals of both sexes, with the females in greater numbers than the males.

The females in heat signal their readiness for mating presenting to the males their swollen vulva.

Usually at the beginning of the rains when there is enough food available, after a gestation of 160 days, every female delivers only one baby that is cared until weaning that occurs around the age of 6 months. Once reached the sexual maturity around the 4-5 years of age, the young males leave the group, whilst the young females remain in the group to which they belong.

The genus is diffused in the African continent south to the desert of Sahara, from Senegal up to South Africa; small populations introduced by man live in some Caribbean islands, inn particular Barbados and St. Kitts.

Presently to the genus are ascribed the following 6 species, in the past deemed subspecies of Chlorocebus aethiops (Linnaeus, 1758); actually, considering the uncertainty of the identifying diagnostic characters, not all scholars are in agreement on the subdivision of the genus in six species, therefore in this place, regardless of their taxonomical value, we limit ourselves to furnish essential elements of reference.

The Grivet (Chlorocebus aethiops Linnaeus, 1758), so called due to the colour of the back of the mantle that is grey-greenish, the muzzle black, with white stripes on the cheek; it is found in the territory of the Horn of Africa (Djibouti, Eritrea, Ethiopia and Sudan).

The Green monkey (Chlorocebus sabaeus Linnaeus, 1766), has the fur that on the back assumes a pale yellow colour, with the tip of the tail, the back side of the thighs and the hair on the cheeks of golden yellow colour. Diffused in western Africa from Senegal up to the Volta River, this monkey has been introduced by man in some Caribbean islands.

The Malbrouck (Chlorocebus cynosuros Scopoli, 1786) has the fur of grey-green colour on the dorsal parts and almost white on the ventral ones; lives in south-western Africa in various habitats, from the forest to the savannah, pushing itself in mountain territories up to 4.500 m of altitude.

The Bale mountains vervet (Chlorocebus djamdjamensis Neumann,1902) characterizes for the fur of dark brown colour and for the face surrounded by white beard; lives in Ethiopia in the territory of the Bale mountains.

The Vervet monkey (Chlorocebus pygerythrus Cuvier, 1821) has the fur of grey-green colour on the dorsal parts, whitish on the ventral ones; its range includes various habitats, from savannah to the forest, of eastern and southern Africa.

The Tantalus monkey presents the mantle dorsally of grey-green colour, whitish ventrally; lives in central Africa in various habitats, from the forest to the savannah.

Erythrocebus

Catarrhine Monkeys known with the name of Patas monkeys or Erythrocebs for the colour of the fur that on the back is reddish, they form a genus that unites species of average dimensions with the body measuring 60 to 90 cm in the males, whilst in the females its reaches 50 cm; the weight is of about 12 kg for the male and about half for the female.

The tail measures almost as the rest of the body; the arms and the legs are well developed. The face presents the front and the nose of black colour with the mouth surrounded of white, the ventral parts are white-grey. The scrotum is of bright blue colour.

Diurnal animal, the Patas monkey is considered as one of the fastest monkeys in the world, capable to reach the 55 km/h; the long limbs make it very fast in running and able to compete even with antelopes and leopards.

The diet of this monkey is omnivorous and if formed by vegetables, mainly of acacia, and also of insects and small vertebrates.

The Patas monkey lives in groups formed by one male and several females, but even in promiscuous groups with more males. Usually the females deliver only one baby after an about 170 days pregnancy.

The genus is diffused in central Africa between the desert of Sahara and the equatorial forests where it is found mainly in open areas of semi-desert areas but can venture also in habitats with rich vegetation, keeping in any case close to uncovered areas.

Presently the genus is divided in three species distinct from each other on the base of significant diagnostic elements and geographically isolated from each other.

The southern patas monkey (Erythrocebus baumstarki Maschi, 1905) distinguishes for the black face and nose; strongly threatened of extinction, presently this species is found only in semi-arid woods of acacia in protected areas of Tanzania and, doubtfully, of Kenya.

The Common patas monkey (Erythrocebus patas Schreber, 1775), known also as Wadi monkey or Hussar monkey, is diffused in semi-arid zones of the savannah of central, western and eastern Africa; it has been introduced by the man also in the Caribbean island of Puerto Rico.

The Blue Nile patas monkey or Heuglin’s patas monkey (Erythrocebus poliophaeus Reichenbach, 1862) lives along the Blue Nile valley, in Ethiopia, Sudan and doubtfully in South Sudan; it characterizes for a pair of white handlebar whiskers on the upper lip.

Allochrocebus

It is a genus of Cercopithecids diffused in the mountain and plain forest areas of central and eastern Africa whose members characterize for the presence of a beard of variable colour from white to pale grey depending on the species and for the articulation of arms and legs more suitable for a more terrestrial style of life than the other members of the family. Presently Allochrocebus that in the past was considered a subgenus of Cercopihecus, is considered a genus on its own, phylogenetically close to the Chlorocebus (Chlorocebus) and to the Erythrocebus (Erythrocebus) To the genus are ascribed three species of which the most known is the Mountain monkey or Hoest’s monkey (Allochrocebus lhoesti Sclater, 1889) distinguishable for a nice white hair collar surrounding its black face.

Miopithecus

Other genus of Cercopithecids including small monkeys amongst the smallest in the Primates, hence the name of Dwarf cercopithecs with which they are commonly indicated; the length of the body of these animals is in fact standing between 30 and 45 cm per a weight of 1,2 kg for the males and 0,8 kg for the females.

They have round head, short muzzle and glabrous face.

Animal of diurnal and arboreal habits, the Dwarf cercopithec usually gathers in numerous groups, formed by 60 to 100 individuals and, unlike the Cercopithecs properly so called, is not a territorial animal.

Good swimmer, is omnivorous and eats fruits, seeds, aquatic plants, insects, eggs, small vertebrates and molluscs.

The females, after an about 160 days long pregnancy, usually deliver only one infant who gets independent when three months old.

To the genus are attributed two species diffused in the rainforest of central-western Africa and whose ranges are separated by the Congo River.

South of the river lives the Southern talapoin (Miopithecus talapoin Schreber, 1774) recognizable for the dark grey colour of the ears and the upper part of the muzzle, whilst north of the river lives the Northern talapoin (Miopithecus ogouensis Kingdon, 1997) distinguishable for the orange colour of the ears and of the upper part of the muzzle.

However, it is to be said that several scholars do not consider Miopithecus ogouensis a species distinct from Miopithecus talapoin judging too uncertain and having no taxonomic validity the characters on which is based their separation.

Pygathrix

It is a genus of Cercopithecids whose species are commonly called Pygathrix or Douc langurs. Diffused in China and Indochina, the Douc langurs are found in forest habitats even if very varied, from the plains up to the mountains where they go up to 2000 metres of altitude.

The genus is presently divided in three species distinguishable from each other mainly for the different colour of their hind limbs.

The Red-shanked douc langur (Pygathrix nemaeus Linnaeus, 1771) characterizes mainly for the bright amaranth colour of the legs and for the presence of reddish areas round the eyes.

The Black-shanked douc langur (Pygathrix nigripes Milne-Edwards, 1871), distinguishes for the black colour of the legs and greyish-light blue of the face.

The Gray-shanked douc langur (Pygathrix cinerea Nadler, 1997) has the legs flecked with grey and orange stripes on the face.

Semnopithecus

Genus of Cercopithecids whose members are commonly called Entellus, maybe from the mythical Sicilian hero Entellus. They are monkeys of medium-large size, with the males averagely 75 cm tall and the females 65, provided with a tail longer than the rest of the body.

The components of the genus characterize for the greyish fur and the face, ears and palms of hands and feet without hairs and of black colour. In the species of the northernmost part of the range, the fur gets longer ensuring good protection from the cold of the winter months. The limbs are long, with the hands and the feet characterized by a remarkable development phalanges. Like many monkeys, the Entellus are equipped with typical black callous formations on the buttocks.

The genus is diffused in a vast range extending for a good part of the Indian subcontinent where is found in different environments, from the high valleys of the Himalayan massif to the tropical coastal forests, from the arid lands to the savannahs.

The presence of the Entellus is common also in urban environments where they are respected and protected by the Hindus who consider them sacred animals. To the genus are presently ascribed the following seven species, in the past considered as many subspecies of Semnopithecus entellus (Dufresne, 1797).

The Kashmir gray langur (Semnopithecus ajax Pocock, 1928) is an arboreal and diurnal species diffused in western India, in the Pakistani Kashmir and in Nepal where is found in wooded areas at an altitude between 2000 and 4000 metres.

The Southern plains gray langur (Semnopithecus dussumieri I. Geoffroy, 1943), is found in the rainforest of south-western and central-western India but but it also goes into anthropized areas.

The Northern plains gray langur (Semnopithecus entellus Dufresne, 1797), lives in the subtropical and tropical dry forests of Pakistan and of central India, but some colonies are found close to the inhabited centres, in close contact with man.

The Tarai gray langur (Semnopithecus hector Pocock, 1928), whose specific name is dedicated to Hector, Trojan hero of the Iliad, lives in northern India where is found in various environments, from the rainforest to the thicket, to the anthropized areas.

The Black-footed gray langur (Semnopithecus hypoleucos Blyth, 1841) is mainly diffused in areas of rainforest of south-western India, along the coastal belt at the boundary between the states of Karnataka and of Kerala; it goes also into the thicket and in the inhabited places.

The Tufted gray langur (Semnopithecus priam Blyth, 1844), species dedicated to Priam, king of Troy in the Iliad that is found in south-eastern India and in Sri Lanka where colonizes the areas of monsoon forest, going also into the not too dense thicket and in areas frequented by man.

The Nepal gray langur (Semnopithecus schistaceus Hodgson, 1840) is a species endemic to south-eastern Asia that lives in Nepal, China, India and in Bhutan.

Nasalis

Other genus of Cercopithecid Monkeys to which is ascribed only one species commonly known with the name of Nasica or Proboscis Monkey (Nasalis larvatus Wurmb, 1787),so called because of a showy hanging and mobile nose, flared towards the middle and traversed longitudinally by a groove; this organ is particularly developed in the adult males where it assumes the look of a small proboscis that gets to cover the mouth, whilst in the females it is smaller and bent upwards. The nostrils open below. The function of such a big nose in the males is not clear; after some it gets the function of sexual recall, after others is a structure of heat dispersion. In any case, a nose conformed in this way works as sound box, giving nasica males a characteristic deep intonation, similar to that of a bass.

The Nasica has a more or less roundish head, with small ears and with long hairs and well developed beard to form a yellowish ruff around the neck. The palms of the hands are dark and have no hairs, like the ischial callosities.

Averagely about seventy centimetres long in the males per a weight from 16 to 22 kg, little less in the females, tha Nasicas have a well developed tail, as long as the rest of the body and without tuft at the tip.

The body is covered by a thick and morbid fur that on the head and on the shoulders assumes a red-brown colouration, whilst on the chest and the abdomen is instead yellow-pale reddish, with a white-greyish spot well delimited in the sacral region; the back and the sides are of pale yellow colour.

The upper limbs are red-yellowish, the lower ones grey-ash, as well as the long tail.

The males have black scrotum and red penis.

Species endemic to Borneo with preference for the coastal zones, the Nasica has essentially arboreal habits and love the highest tops of the giant trees populating the virgin forest of Borneo, in particular the forests of mangroves near the water streams, where it nourishes mainly of leaves and fruits, even the less ripe ones.

More active in the morning, it usually lives united in family groups formed by one single male with 2-7 adult females with the infants. The reproductive season is from the beginning of spring up to autumn; after an about 160 days long gestation, the females deliver only one baby who is cared mainly by the mother for about one year. As a result of the intensification of the anthropic activities, in particular of the deforestation and of the practice of the mariculture of the shrimps, this species is presently in danger of extinction.

Macaca

The Macaques, name with which are commonly indicated the species of this genus, are Catarrhine Monkeys with protruding muzzle and without hairs, whose specific identificative character is represented by the tail that in some species is as long as the body, in others is short, in others more reduces to a vestigial organ like in the Barbary ape. Of medium height, they are 40 to 75 cm tall and weigh 2,5 to 18 kg; the males are about the double than the females.

The colour of the fur is varied, from brown, to grey to black. They have diurnal habits and lead activities mainly on the ground, but they are also good climbers. They eat mainly fruits, but also other vegetable substances, of insects and small vertebrates.

Gregarious animals, The Macaques live in groups sometimes even very numerous where the females are averagely in a quantity of three to four times bigger than that of the males. The females usually deliver only one son after a gestation of 160-170 days; the sexual maturity is reached when 6-7 years old in the males, 3-4 years in the females.

Nowadays present in Africa and in the Indonesian region, the Macaques during the Plio-Pleistocene were diffused in a much wider range that included also part of southern Europe, as witnessed by fossil remains among which those attributed to the Dwarf macaque or Dwarf Barbary ape (Macaca majori Schaub e Azzaroli, 1946) and Macaca  florentina (Cocchi, 1872) found respectively in Sardinia and in Tuscany. Among the 22 species that presently are attributed to the genus, the most known is the Barbary ape or Barbary macaque or Magot (Macaca sylvanus  Linaeus, 1758), living in the medium-mountainous forests of north-western Africa, especially in Maghreb (Morocco, Algeria and Tunisia); a group of little more than 200 specimens of this species lives on the Rock of Gibraltar, maybe introduced during the Islamic domination of Spain.

Among the other Macaques, are to be kept in mind the Silenus, called also Lion-tailed macaque or Wanderoo (Macaca silenus Linnaeus, 1758) species with the fur of shiny black colour and the characteristic mane of whitish hairs surrounding the muzzle, diffused in the rainforest of Malabar, South-West India; the Java macaque known also with the names of Long-tailed macaque or Cynomolgus or Crab-eating macaque (Macaca fascicularis Raffles 1821) is a species amply diffused in the forests of various countries of south-eastern Asia where it is considered as standing among the most dangerous invasive species; the Sulawesi crested macaque (Macaca nigra Desmarest, 1822), species endemic to the rainforests of Sulawesi in Indonesia and of the nearby islands with its characteristic crest of long hairs that raise when the animal is excited; the Tibetan macaque (Macaca thibetana Milne-Edwards,1870) , that lives in the mountain rainforests up to more than 2000 metres of altitude of southern China; the Taiwanese macaque (Macaca cyclopis Swinhoe, 1862) species endemic to Taiwan where lives in the temperate forest and in rocky zones having poor vegetation.

Mandrillus

It is a genus of Cercopithecids to which are attributed two species, commonly known with the names of Mandrill and Drill, who, due to their strong resemblance to the Baboons, in the past where included in the genus Papio. They are of terrestrial habits and live mainly in the tropical rainforest of central Africa; they have an omnivorous diet made mainly of fruits, other vegetable substances, insects and small vertebrates. Gregarious animals, they live merged in usually numerous groups.

The Mandrills (Mandrillus sphinx Linnaeus, 1758), stand out at first glance due to their showy colouration and also for being the biggest Monkeys in the world, after the Hominids; their dimensions can vary from 60 to almost 80 cm, with a weight averagely of 12 kg in the females and about the double in the males.

The Drills (Mandrillus leucophaeus F. Cuvier, 1807) differ from the Mandrills being a little smaller and also much less colourful.

Papio

It is a genus to which are attributed the species known commonly with the names of Baboons or Paviani. They are Cercopithecid Monkeys of dimensions included from 40 to 110 cm and with a weight that in the bigger species may even exceed the 30 kg.

The Baboons are characterized by a marked sexual dimorphism, with the males that weigh about the double than the females, have the canines more developed and in some species have a showy mane on the neck and on the shoulders. Both sexes have an evident canine muzzle, the eyes close together and robust jaw; the tail is long and can even reach 80 cm. But the muzzle and the buttocks that are glabrous, the body is covered by a fur variable from yellowish, olive, brown and silvery depending on the sex and the species.

The genus is present in almost all Africa and is absent only in the north-western part of the continent; only the Hamadryas baboon (Papio hamadryas Linnaeus, 1758) lives in some zones of the Arabian peninsula.

The choice habitats of these Monkeys are the sparse forest, but they frequent also the savannah, the steppe and the semi-desert or rocky zones.

Of diurnal habits, the Baboons are excellent climbers but carry out mainly activities on the ground where they move with quadrupedal gaits.

They are omnivorous animals, they mainly eat various vegetables but also insects and small vertebrates, mammals includes.

They live in troops that may be formed by 5 to 250 specimens depending on the species and the available resources. Clashes between troops for the access to food resources are not rare and resolve in fights between males.

The Baboons communicate with each other with complex vocal and even gestural systems.

After a gestation lasting about seven months, the females usually deliver only one son that is immediately able to attach to the hair of the mother’s belly who, in this way, can easily carry it during the movements of the troop.

Besides by the mothers, the infants are cared also by all members of the troop and in particular by the big adult males who provide to the defense of the weakest individuals.

To the genus are presently assigned the following species.

The Hamadryas baboon (Papio hamadryas Linnaeus, 1758) is a species that characterizes for the marked sexual dimorphism with the males who are provided with a thick white-greyish fur that on the neck and on the shoulders forms a real mane; the face has no hairs and is black, with a canine muzzle. Conversely, the females are smaller than the males and have the fur with short hairs and of brownish colour.

Both sexes have shoulders higher than the rump and present ischial callosities well developed and without hairs. The tail is 40-60 cm long.

The Hamadryas baboon lives in the territories between the two shores of the Red Sea, and that includes Egypt, Ethiopia, Eritrea, Somalia, Yemen and Saudi Arabia.

The Guinea baboon (Papio papio Desmarest, 1820), the smallest among the species of the genus, is diffused in a range spreading in the territories of central-western Africa, from Senegal to Sierra Leone.

The Anubis baboon or Olive baboon (Papio anubis Lesson, 1827), whose name comes from Anubis, deity of the old Egypt, is a robust monkey, with well developed muzzle, long and pointed, armed with a sturdy set of teeth and with the tail having at its extremity a tuft of hairs; for these characteristics and for the four-legged gait somewhat reminds a dog.

Also in this species the males have on the neck and on the shoulders a mane of long hairs.

The Anubis baboon is diffused in the central territories of the African continent and in some mountain regions of the desert of Sahara.

The Yellow baboon (Papio cynocephalus  Linaeus, 1766), whose scientific name from the old Greek κυνοκἐφαλος, means dog head, refers to the stocky head with the long muzzle, vaguely similar to that of a big dog, that characterizes this species.

Conversely, the common denomination of Yellow baboon is due to the yellow-brown fur covering most of the body, excepting the cheeks that are adorned with a tuft of thick whiskers on the sides of the muzzle and the internal surface of the limbs that are of white colour.

The ischial callosities are well developed and are of black colour. The females deliver one baby at a time after an about 170 days long pregnancy.

The species is amply diffused in the zones of savannah and of forest of central-eastern Africa.

The Chacma baboon (Papio ursinus Kerr, 1792) is the largest species of the genus, reaching the length of more than 110 cm and a weight varying between 15 and 31 kg; the tail averagely is 70 cm long.

Like the other species of the genus, the males of this species have neatly higher dimensions than the females and more developed canines, but, apart these, they do not have the mane on the shoulders. The colour of the fur is dark brown on the back and greyish on the ventral surface; the extremities of the limbs are usually black.

The species is diffused in southern Africa where it prefers the savannah, steppe and open forest environments.

Colobus

It is a genus that unites species of Cercopithecids characterized by the strong reduction of the thumb; hence the scientific name from the Greek “monco”, and by the striking contrast between the black colour of the fur and the white of the tail, long about 50 to 100 cm.

The dimensions of the Colobuses do not significantly differ from those of the other members of the family they belong to and are averagely included from 45 to 70 cm, with the males remarkably bigger than the females.

Of diurnal habits and mainly arboreal, the Colobuses live in small territorial troops composed by an adult male, 2-6 females and their infants. Their diet is based mainly on vegetables, especially leaves. The females usually deliver one baby at a time, after a 150-180 days long pregnancy.

The Colobuses are found in different habitats of Africa south to Sahara, such as the tropical rainforest, the mountain forest up to 3000 m of altitude and the mangrove forests.

Presently are attributed to the genus the following five species :the Angola colobus (Colobus angolensis Sclater, 1860) of the eastern and southern Africa forests, the Guereza (Colobus guereza Rüppell, 1835), known also as Mantled guereza, Eastern black-and-white colobus or Abyssinian black-and-white colobus diffused all over the equatorial Africa, the Western black-and-white colobus or King colobus(Colobus polykomos Zimmermann, 1780) that lives in the plain and mountain rainforests of a limited region between Gambia and Ivory Coast, the Black colobus or Satanic black colobus (Colobus satanas Waterhouse, 1838) of central-western Africa, the Ursine colobus (Colobus vellerosus Geoffroy, 1834), diffused in western Africa.

Presbytis

It is a genus of Cercopithecids to which pertain rather small and slender Monkeys, characterized by the muzzle particularly full of wrinkles that gives them the look of old, hence the name from the scientific Greek (πρεσβύτης that means “old”).

It is to be noted that with the same name of Presbytis are called also the species of Trachypithecus, other genus of the family of the Cercopithecids.

They are monkeys with the mantle of colour varying from brown, to grey or black on the dorsal parts and pale grey in the ventral ones, at times even red-orange.

In some species the fur is adorned of particular designs on the head or on the sides.

They live in the forests of plain of the southern territories of the Malay peninsula, in Borneo, in Java, Sumatra and in the adjacent islands.

Mainly arboreal animals, the Presbytis of the genus here considered form troops hierarchically structured and composed by 4 to 15 individuals guided by only one male.

The females usually give birth to one child at a time after a 150-180 days long pregnancy.

Mostly because of the reduction of their natural habitat due to the deforestation for anthropic activities and also for the hunting to which they are subject because they devastate the plantations, all the species of the genus are considered as more or less at risk.

Presently to the genus are attributed 17 species distinguishable from each other on the basis os the drawings and the hues of the fur and that with very limited ranges live mainly in the large islands of the Indonesian archipelago of Sumatra and Borneo.

In restricted territorial areas of Sumatra live the Black-and-white langur (Presbytis bicolor Aimi and Bakar, 1992), the Black-crested Sumatran langur (Presbytis melalophos Raffles, 1821), the Mitered langur (Presbytis mitrata   Eschscholtz, 1821), the Black Sumatran langur (Presbytis sumatrana Muller and Schlegel, 1841), the Thomas’s langur (Presbytis thomasi Collett, 1893) and the East Sumatran banded langur (Presbytis percura Lyon, 1908).

Numerous species of the genus. are found also in Borneo.

Some of them are exclusive to the large island such as the White-fronted surili (Presbytis frontata Muller, 1838), the Miller’s langur (Presbytis canicrus Miller, 1934), diffused in the eastern region and the Sarawak surili (Presbytis chrysomelas Muller, 1838), the Hose’s langur (Presbytis hosei Thomas, 1889 and the Maroon langur (Presbytis rubicunda Muller, 1838).

Are no to be forgotten the Natuna Island surili (Presbytis natunae Thomas e Hartet, 1894), known only for the Natuna islands between the Malay peninsula and Borneo, and the Mentawai langur (Presbytis potenziani Bonaparte, 1856) exclusive to the Mentawai islands off Sumatra.

Piliocolobus

In the past all species ascribed to this genus, also indicated with the collective name of Colobi, were inserted in the genus Colobus and only recently, after a taxonomic revision, have been assigned to a genus on its own, Piliocolobus.

Presently, about 17 species are assigned to this genus.

Some of these, in turn divided in subspecies, are distinguishable each other essentially of the different chromatic model of the fur, whose basic colour is, however, the red, hence the name of red Colobi.

The species of Piliocolobus are diffused in central Africa in territories of rainforest, close to the permanent waterways but also in savannahs and in mangrove forests.

Trachypithecus

Called also Presbytis or Langur, as well as with the Indonesian name of Lutung, the species of the genus are Cercopithecid Monkeys of rather slender build reaching a length of 40-80 cm and a weight of 5 -15 kg, with generally the males bigger than the females.

Typically, the arms of these animals are shorter than the legs and the hands have reduced thumbs. The tail is long. The mantle is of variable colour depending on the species from black to grey to yellow-orange, at times very colourful, whilst the ventral parts are paler; the hairs on the head form a sort of hood.

The Presbytis of this genus are arboreal animals and of diurnal habits and frequent the rainforests but may be encountered also in the mountain forests.

They nourish of vegetable substances, especially leaves, fruits and buds. Territorial animals, they live in troops formed by one male and some females. After a pregnancy of about seven months one only baby comes to life, rarely two, whose care is provided by the mother and the other females of the harem.

The genus, to which are presently attributed 17-18 species, is diffused in a range spreading over most of south-eastern Asia and the southern extremity of India and the Sri Lanka.

Among the most representative species we mention the following.

The Javan langur known also as Ebony lutung or Budeng (Trachypithecus auratus È Geoffroy, 1812) lives in the internal and peripheral areas of the rainforests, the Silvery lutung (Trachypithecus cristatus Raffle, 1913) is found in the coastal forests of mangroves of the territory going from Burma up to Indochina and Borneo, the François langur (Trachypithecus francoisi Pousargues, 1898) is diffused in the areas of monsoon rainforest of northern Vietnam, central Laos and southern China.

The Laotian langur (Trachypithecus laotum Thomas, 1911) is endemic to central Laos dry subtropical or tropical forests, the Spectacled langur or spectacled leaf monkey (Trachypithecus obscurus Reid, 1837), populates with numerous subspecies areas of rainforest of Malaysia, Myanmar and Thailand, and also the Golden-headed langur (Trachypithecus poliocephalus Trouessart, 1911) living in Vietnam, on the Island of Cat Ba, and the Purple-faced langur or purple-faced leaf monkey (Trachypithecus vetulus Erxleben, 1777), whose range has dramatically reduced due to the anthropogenic activities and presently is confined on the mountains of the Horton Plains National Park or in the rainforest of the cities of Kitulgala and Galle.

Hylobatids (Hylobatidae)

They form a family of Catarrhine Monkeys whose members characterize, apart the smaller dimensions, especially for the remarkable length of the arms if compared to the dimensions of the body, for the habits exclusively arboreal and for the use of the brachiation as main form of locomotion.

Commonly known with the name of Gibbons, they are Monkeys that, like the Hominids, do not have tail; moreover, they are provided of ischial callosities and normally assume an erect position. The species of the genus Hylobates do not have cheek pouches.

The body is covered by a fur of variable colour, depending on the species, as well as on the sex and the age, from black, to grey, to brown or to white; at times the mantle is adorned of variously coloured spots.

The Gibbons lead a diurnal life and eat mainly fruits, leaves and invertebrates.

Social animals, they live merged in small family groups, averagely composed by a monogamous couple, and its kids; they have a keen sense of territoriality and protect actively their own territory by means of a series of manifestations, mainly vocal.

Some species have a big laryngeal pouch in the front part of the neck, that, inflating, works as sounding board that amplifies the sound calls.

The family is diffused in south-eastern Asia and in the Malay archipelago in habitat of tropical and subtropical rainforest, mainly in zones at low altitude.

Presently are ascribed there sixteen species distributed in four distinct genera by the number of chromosomes, Hoolock (2n=38), Hylobates (2n=44), Symphalangus (2n=50) and Nomascus (2n=52).

All species of the family stand at risk of extinction, due to the increasing anthropization of t he Asian South-East with resulting degradation and fragmentation of their habitats.

Hoolock

Commonly called with the name of Hoolock the species of the genus reach a height of 60-90 cm, with an arms opening of 180 cm per a weight usually included from 6 to 9 kg.

In addition to the number of chromosomes (19 pairs), the Hoolocks characterize for a marked sexual dimorphism concerning the colour of the fur, of black colour with a white band on the front in the males, grey-brown, darker on the neck and on the chest in the females.

Both sexes present some rings of white hair around the eyes and the mouth that recall a mask.

Monkeys of diurnal and arboreal habits, the Hoolocks have a diet mainly based on fruits, insects and leaves.

They are social animals, they use for communicating a complex series of vocalizations, and form monogamous couples.

The females, after a 7 months long pregnancy, deliver babies with a white cream fur that gets the final dark colour only when the sexual maturity will be reached, between 8 and 9 years of age.

The genus, divided in two species indicated with the names of Western hoolock (Hoolock hoolock Harlan, 1834) and Eastern hoolock (Hoolock leucinedys Groves, 1967), presents a divided range extending from north-eastern India to Myanmar (Burma) and with small populations also in Bangladesh and in the eastern part of south-west China.

Hylobates

Commonly indicated with the collective term of Gibbons the species of this genus are Hylobatids characterized by an endowment of 22 pairs of chromosomes.

With a weight varying from 4,( to 7 kg the Gibbons are the smallest members of the family. The fur is of variable colour, from black to brown or to grey-yellowish. The gibbons carry one mainly an arboreal life and rarely get down to the soil.

They live united in small family groups, formed by monogamous couples and sons, with an own well defined territory.

The Gibbons are known for the production of elaborate vocalization models with various functions, mainly related with the control of the territory and with the consolidation of family ties.

Omnivorous animals, they essentially eat fruits but also leaves and buds and small animals.

The females, after a gestation of about seven months, usually deliver only one baby that is cared for a couple of years and that reaches the sexual maturity at an age variable between 6 and 8 years

The genus Hylobates is amply diffused in the tropical river forest from south-eastern Asia, from southern China to Borneo, Sumatra up to the western territories of Java.

Presently in the genus are comprised about six species among which must be mentioned the Lar gibbon or White-handed gibbon (Hylobates lar Linnaeus, 1771), the Silvery gibbon or Javan gibbon or Uau-uau (Hylobates moloch Audebert, 1798) and the rare Agile gibbon (Hylobates agilis Cuvier, 1821).

Nomascus

It is a genus of hylobatids to which presently are attributed species, they also known with the collective of Gibbons, characterized by a chromosomic endowment formed by 26 pairs of chromosomes.

They are monkeys of about 60 cm of height and of 7-8 kg of weight that manifest a marked sexual dimorphism in the colour of the fur that in the males is mainly of black colour, whilst in the females it gets a brown-yellowish hue with a black spot at the top of the head.

The Gibbons of Nomascus lead an arboreal and diurnal life, nourishing mainly of fruits and other vegetable food and occasionally also of insects.

They live united in family groups formed by monogamous couples and sons.

The genus is diffused in the zones of tropical rainforest of southern China, Vietnam, Laos and eastern Cambodia.

Presently are ascribed there 6 species among which the Black crested gibbon (Nomascus concolor Harlan, 1826), the Red-cheeked gibbon (Nomascus gabriellae Thomas, 1909), relegated in the extreme south of Laos, southern Vietnam and in eastern Cambodia, and the Northern buffed-cheeked gibbon (Nomascus annamensis Van Ngoc Thinh et al., 2010)

Symphalangus

Distinguishable on the base of the chromosomic endowment formed by 26 pairs of chromosomes, the Symphalangus is a genus of Hylobatids diffused in the forests of Indonesia, Malaysia and of Thailand.

At the state it includes only one species, the Siamang (Symphalangus syndactylus Raffles, 1821), the biggest species of extant Gibbons, reaching the metre of height, per a maximum weight of 14 kg.

The opening of the arms can reach the 2 m.

It is a monkey distinguishing from the other Gibbons because having the second and third toe of the feet partially united by a membrane, hence the specific name, as well as for presenting in both sexes a big hairless sac under the throat, able to swell up to the size of the head itself, that allows the emission of sharp or resonant sounds or songs.

The Siamang differs also for having low front, very sunken eyes and wide and flat nose with big lateral nostrils; moreover the mouth is particularly wide and the chin is receding. The face is practically without hairs excepting a thin pair of mustache. The fur is black.

Of arboreal habits, the Siamangs nourish essentially of vegetable substances, in particular ripe fruits and tender leaves but also of flowers and small animals, mostly insects.

The Siamangs are monogamous and usually form family groups formed by the parents and by their infants that remain until when they reach the maturity.

The females deliver after a gestation of 6-7 months; the babies are cared by both parents.

Hominids (Hominidae)

They form a family of Catarrhine Monkeys to which until a few decades ago was ascribed only the human species (Homo sapiens), presently are included there also most of the so-called anthropomorphic monkeys, such as Orangutans, Gorillas and Chimpanzees yore united inside the family of the Pongids, now downgraded to subfamily of the Hominids, that of the Ponginae.

In turn, the family of the Hominids is divided in the genera Pongo, Gorilla, Pan and Homo.

Nevertheless, in this regard it should be noted how some biologists believing that the distinction between the genera Homo and Pan is not supported by sufficient significant elements and on the base of evident genetic similarities, propose the reclassification of common Chimpanzee as Homo troglodytes and of Bonobo as Homo paniscus.

Pending further studies on the matter, here we shall illustrate the representative elements of the four genera mentioned above, considering still premature whatever consideration of systematic character.

Pongo

Represented by big monkeys, it is a genus whose scientific name comes from mpungu that, in the local language, means great ape of the woods, whose members are more commonly known with the name of Orangutan, term originating from the Malay words orang “man” and hutan, “forest”, that is, man of the forest.

Only Primates of big size that nowadays can be found outside the African continent, the Orangutans live in the swampy rainforests with thick vegetation of Borneo and of Sumatra.

They are Catarrhine Monkeys of solitary and arboreal habits that feed mainly of vegetables but also of insects, eggs of birds and small vertebrates.

Like the Chimpanzees and the Bonobos, the Orangutans have developed the usage of tools and, endowed with excellent capacities to relate with humans, are capable to learn and repeat some actions, such as that of driving nails or cutting a piece of wood with the saw.

Today the genus is divided in 3 extant species, distinguishable from each other mainly on the mitochondrial DNA basis. The Bornean orangutan (Pongo pygmaeus Linnaeus, 1760), species endemic to Borneo where lives in the warm and humid tropical forests and also close to the coastal swamps, the Sumatran orangutan (Pongo abelii Lesson, 1827), confined in the northern part of the Indonesian island of Sumatra, and the Tapanuli orangutan

(Pongo tapanuliensis Nurcahyo, Meijaard, Nowak, Fredriksson & Groves, 2017) reported for the tropical forests of broad-leaved trees in the northern part of Sumatra. Physically very similar to the Sumatran orangutan, from which it distinguishes mainly for the hair of the mantle that is more rippled and of a less reddish colour, the Tapanuli orangutan is particularly rare and at risk of extinction.

Gorilla

It forms a genus of the family of the Hominids whose members characterize at first sight for the build particularly robust and stocky and for the mantle of grey-blackish colour. Averagely 1,25 to 1,75 metres tall, for what concerns the weight, the Gorillas display a marked sexual dimorphism with the males that can reach the 200 kilos whilst the females weigh between 70 and 90 kg. The arms are remarkably longer than the legs and have an opening between 2 and more than 2,75 metres; the hands and the feet are very wide, with big thumbs and with the big toes usually opposable.

Relatively agile climbers, the Gorillas are essentially terrestrial animals and on the ground they move on all fours on their knuckles, that is to say burdening the weight of the body on the second and third phalanx. Like other primates, the Gorillas have a distinctive fingerprint and, like all other members of the family, have no tail.

Diffused in the central regions of Africa, until recent past all Gorillas were grouped in only one species. Presently are recognized two species distinguishable from each other on morphological and behavioural basis as well as for the different colour of the fur: the Western gorilla (Gorilla gorilla Savage, 1847) with the fur of grey-brownish colour, and the Eastern gorilla (Gorilla beringei Matschie, 1903 with the typical fur of black colour. In turn, both species are divided in two subspecies.

Pan

It is considered a genus of Hominids whose present members, Chimpanzee and Bonobo, until now classified respectively as Pan troglodytes (Blumenbach, 1775) and Pan paniscus (Schwarz, 1929), result species so much similar to the human species (Homo sapiens Linnaeus, 1758) to oblige several scholars to include them in the same genus Homo. Actually it has been proven that Chimpanzee, Bonobo, and Man are extremely close from the DNA point of view, and share a very high percentage of their genetic heritage.

In their natural state the Chimpanzees of the species Pan troglodytes live, divided in four subspecies, only in the tropical forest of the equatorial zone of central-western Africa. They are monkeys of great stature that in the female may reach 130 cm of height per a weight of 45 kg, whilst the males may be even 160 cm tall with a weight that can reach 65 kg. The colouration of the hair is usually very dark and tending to black, even if have been reported exceptional cases of albino chimpanzees. Essentially arboreal animal, they live in more or less numerous troops, composed of males, females and young.

The Bobobo (Pan paniscus Schwarz, 1929), known also as Pygmy chimpanzee or Dwarf chimpanzee, distinguishes from the common Chimpanzee as having relatively long legs, the head equipped wit tufts of hairs on the top and the face dark with pink lips; the young have the tail with the plume tip until adulthood. Of arboreal and also terrestrial habits, this monkey is able to walk in an erect position, characteristic this that together with the traits of the face confer it a look more similar to the human beings than what can be the common Chimpanzee. The Bonobo lives in the primary and secondary rainforests of central Africa, usually between 300 and 700 metres of altitude; occasionally, it may be met also in non woody areas or in savannahs.

Homo

Traditionally it forms a genus where is ascribed only the species represented by the modern man, Homo sapiens (Linnaeus 1758. Indeed, as aforementioned, the minimal genetic differences noted between Man, Chimpanzee and Bonobo have obliged some scholars to reconsider Linnaeus’ original scheme and to hypothesize their attribution to the same genus Homo.

On the other hand, it is however necessary to remember that after other scholars it’s instead the term Homo sapiens to be inadequate and that our species should be reclassified inside the genus Pan, therefore as Pan sapiens; this diversity of views means that the systematic belonging of Chimpanzee, Bonobo and Man is still an open question. Consequently, waiting for further and valid elements supporting one or the other superior hypothesis, here we shall follow the tradition that attributes to Homo the status of genus and of which is part the present species (Homo sapiens Linnaeus, 1758) together with about twenty other species, all extinct.

However, also due to the shortage of fossils remains, the evolutionary path of this branch of our most direct ancestors and its specific division is not yet completely clear; therefore we shall limit ourselves to mention some among the most interesting, like the Neanderthals (Homo neanderthalensis King, 1864), whose extinction is placed in a period between 25.000 and 30.000 years ago, the Homo floresiensis, whose specific status is of doubtful value and that it is thought having survived up to 12.000 years ago; and yet the Homo of Desinova or woman X whose existence in 2010 has been hypothesized on the base of the mitochondrial analysis of the DNA done on the rest of a finger found in Siberia, on the range of the Altai Mountains, and that is thought it has been living in a period included from 70.000 and 40.000 years. And again, the Homo habilis (Leakey et alii, 1964) is an extinct species of hominid, appeared in the Pleistocene and lived from about 2,4 to 1,44 million years ago.

Finally, we must not forget the Pithecanthrope or Java man (Homo erectus Dubois, 1894) considered as the first hominid able to prepare and utilize chipped stone tools, to use the fire and probably also to tan and work the hides and also get a more elaborate use of the foods than the previous primitive men.

 

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