Brown spider monkey

General characteristics
The genus Ateles includes all species known as spider monkey marimondas, they belong to the Subfamily Atelinae and family Atelidae, which also include the genera Lagothrix (woolly monkeys), Brachyteles (muriqui) and Alouatta (howler monkey). These species constitute the largest group of neotropical monkeys. Morphologically they are characterized by having prehensile tails, the end of the tail is free of hair and has a callus, which is used to support their body during feeding or locomotion. ateles along with Brachyteles, use a quick suspensory locomotion, and are characterized by elongated bodies and limbs that have adapted to their distinctive locomotor pattern. There is no a distinctivesexual dimorphism in body size or color in spider monkeys, but males are slightly larger than females, and females have  a hypertrophied pendulous clitorides (clitoris) that is markedly larger than the adult male penis. The name of the genus Ateles, from the Greek and refers to the absence of the thumb (Defler, 2003).

The body of Ateles hybridus has a length of about 40-50 cm, with a tail of about 72-82cm and the body weight is 4 to 8 kg or more (Defler, 2003). The hair color is brown wood and gray or light brown on the ventral side. It has a distinctive white triangular patch on the forehead, and faint white lines on the sides of the face. Iris color is usually brown and some individuals have bluish-gray eyes.

Gestation lasts from 226 to 232 days, a new baby is conceived every 3 years. Sexual maturity occurs at 4 or 5 years and individuals of this species can live for 20 years. (Defler, 2003)

The taxonomic classification of Ateles hybridus, as well as species and subspecies of Ateles in general has been discussed for years by several authors, it is a difficult group to understand systematically, due to its high variation and hybridization(Kellogg & Goldman, 1944 ; Hershkovitz, 1969, 1977, Hernandez & Koper, 1976;Wolfheim, 1983, Froehlich et al., 1991). This species comprises two subspecies Ateles hybridus hybridus and Ateles hybridus brunneus (Hernandez-C. & Cooper (1976), Froehlich et al. (1991), Rylands et al (2000), Defler (2003)). Ateles hybridus hybridus being the subspecies present in Venezuela.

Social organization
Social organization in Ateles is complex and unique among neotropical primates. Spider monkeys have been of particular interest to primatologists and behavioral ecologists because of their apparent social convergence with chimpanzees due to their common,  fission-fusion social organization. Spider monkeys live in groups of 10 to 30 or more individuals, each morning the members of each group separate into small subgroups. Some individuals travel as solitaries, others in pairs, trios or quartets, the size and composition of each group changes frequently during the day. The size of the subgroups is related to the availability of ripe fruit, suggesting that the fission-fusion organization may represent an adaptation to reduce levels of food competition during times of scarcity (Chapman, 1990, Symington, 1990).

Distribution in Venezuela
In Venezuela, according to historical records, Ateles hybridus are distributed in the tropical forests of the Basin of Lake Maracaibo, Tachira, Trujillo and Apure states, in the Serrania de Perija in Zulia state, Sierra Nevada National Park in Merida state, in the  Ticoporo Forest Reserve and Caparo Forest Reserve  in Barinas state, San Camilo Forest Reserve in Apure state, northern Cordillera Central Coast, where it has been observed in different locations as in the El Avila National Park and Guatopo National Park, and some localities Cúpira of Barlovento in Miranda.