Comparison of the arboreal dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) of the wet and dry forests of the Western Ghats, India

Data on the composition, abundance, and guild structure of the arboreal dung beetle communities associated with dry and wet forests in the Western Ghats, a global hotspot of biodiversity in southwestern India, is provided. Five arboreal dung beetle species (Caccobius gallinus Arrow, Caccobius meridionalis Boucomont, Onthophagus vladimiri Frey, Onthophagus furcillifer Bates, and Onthophagus centricornis (Fabricius)) were collected. Overall abundance was high in dry forests, and all species were tunnelers in both wet and dry forests. Analysis of the species composition leads to the question why only members of the modern tribes Onthophagini and Sisyphini are arboreal in the Afrotropical and Oriental regions and the primitive tribe Canthonini alone in the Neotropical region. Lower abundance of arboreal dung beetles in the Western Ghats is attributed to the lower abundance of arboreal primates in this area. Higher abundance and diversity of monkey populations in the dry forest region and the availability of dung in the arboreal canopy for a longer duration in the dry forests with a very short rainy season lead to higher abundance of arboreal dung beetles in the dry forests. Onthogphagus centricornis, the dominant arboreal dung beetle in both dry and wet forests in the southern Western Ghats, is the smallest arboreal dung beetle species recorded so far. Smaller size range of all arboreal dung beetle species indicates that small size must be considered as the major adaptation for arboreality. Based on their capacity to exploit dung resources both on the ground and in the arboreal environment, it is proposed that the arboreal dung beetle species are a more modern group than the exclusively ground-based dung beetle species.