Preliminary revision of the charismatic whirligig beetle genus Porrorhynchus Castelnau (Coleoptera: Gyrinidae)

Within Gyrinidae, the tribe Enhydrini is predominantly composed of large and conspicuous whirligig beetles that frequent a variety of habitats from lotic to lentic waters. Of the enhydrines, the Indo-Pacific genus Porrorhynchus is one of the most charismatic members, with several species representing the largest of the known whirligig beetles. Despite their large size and unique morphology, the genus is in desperate need of revision. The current classification for the genus includes 3 subgenera, 5 species, and 10 subspecies distributed unevenly amongst three of the species. Here a review of the history of the Enhydrini and a preliminary revision of the genus Porrorhynchus is presented, including a discussion of novel morphological characters in relation to phylogeny and classification.