A new species with high sexual dimorphism of Xenelmis Hinton (Coleoptera: Elmidae) from Mount Roraima National Park, Brazil

Abstract

Xenelmis is one of the 51 Neotropical genera of the aquatic beetle family Elmidae and is currently represented by 15 species distributed throughout the Neotropics. This genus of tiny beetles is especially well represented in South America, where all but one species can be found, and Brazil has the greatest richness, with ten species recorded so far. Here we describe and illustrate Xenelmis tuchaua sp. nov., a new Elmidae species with remarkable sexual dimorphism and unique diagnostic characteristics. The new species was found in an Amazonian stream located in Mount Roraima National Park, Roraima state, Brazil. We provide an updated species list for Xenelmis with comments on the occurrence of sexual dimorphism in the genus.