Abstract
Objectives: Colobines are a group of foregut-fermenting AfroEurasian monkeys that includes more than 70 species grouped into 10 genera which are widely distributed throughout Asia and Africa. Colobines are classified as tripartite or quadripartite based on the number of compartments in their stomach. To expand our understanding of their morphophysiological digestive characteristics, we attempted to visualize their stomach using photographs, examine the ontogenetic development of gastrointestinal size, and evaluate the interspecific differences in gastrointestinal size relative to the body size with a special reference to differences in stomach types.
Materials and Methods: Gastrointestinal tracts were dissected from 144 deceased colobine specimens in the Japan Monkey Centre stored in formalin. We measured the gastrointestinal tracts of nine species with a tripartite stomach and two species with a quadripartite stomach. We used an allometric linear regression model to establish how body mass was related to stomach weights and all intestine lengths.
Results and discussion: Our results support previous findings about primate and colobine macroscopic digestive tracts. In particular, we document the small size of the openings connecting stomach compartments and found that it may be difficult to differentiate between a bulging haustrated pouch and a real praesaccus. The stomach mass analyses indicated hyperallometric stomach growth in colobine infants as opposed to isometric scaling in juvenile specimens and hypoallometric scaling in mature specimens, which is similar to findings in other foregut fermenters. Stomach weight was greater in species with quadripartite stomachs than in species with tripartite stomachs, which suggests that species with a quadripartite stomach possibly have a larger stomach capacity, supporting the concept of their evolutionary adaptation to folivory.
Matsuda, Ikki