The giant water scavenger beetles: A review of the New World Hydrophilus (Coleoptera: Hydrophilidae)

The genus Hydrophilus contains some of the largest aquatic beetles in the world, with some species exceeding five centimeters in length. Their cosmopolitan distribution, often high abundance, and large size make them both easily recognizable and frequently collected. However, positive identification of the different species can be difficult, with the last revision of the genus more than 100 years old. The New World species can be divided into two distinct subgenera: Hydrophilus s.str. and Dibolocelus. We reviewed the New World Hydrophilus and provide new diagnostic and distribution information on the genus, including the description of two new species and one synonymy. We found there to be 11 species, including the two new species, in the subgenus Dibolocelus and 8 species in the subgenus Hydrophilus s. str. Secondary sexual characters proved to be particularly useful for species separation.