Taxonomic composition of Scarabaeinae dung beetles (Coleoptera: Scarabaeidae) inhabiting fluvial islands in the southern Brazilian Amazon

We evaluated the taxonomic composition of Scarabaeinae dung beetles inhabiting fluvial islands in Juruena River, southern Brazilian Amazon. We sampled seven islands and two localities on each side of the mainland. We collected 41 species, all of which are widely distributed in the Amazon rainforest. Nine of these were exclusive to the islands, 24 were exclusively found on the mainland while eight species were found in both the islands and the mainland. The insular dung beetle fauna is mainly composed of typical species of várzea forest or edge forest/gap with the absence of Eurysternus and elements of primary forest in the Amazon. This result suggests that three main processes are shaping these communities: flooding and associated disturbance events, resource competition (presence of primates) and differential dispersal power among species. Depending on the context and age of island formation all these processes could have different levels of importance. Specific questions regarding these processes requires a previous knowledge of the taxonomic composition of these communities. © 2015 Société entomologique de France.