Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini).

The Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera: Dytiscidae: Hydroporinae: Bidessini) is revised. Thirty species are recognized. The following new species are described: Hydrodessus bimaculatus sp. n. (Venezuela), Hydrodessus brevis sp. n. (Venezuela), Hydrodessus concolorans sp. n. (Venezuela), Hydrodessus continuus sp. n. (Venezuela), Hydrodessus disjunctus sp. n. (Suriname), Hydrodessus fasciatus sp. n. (Brazil), Hydrodessus imparilis sp. n. (Ecuador), Hydrodessus keithi sp. n. (Brazil, Colombia, Ecuador), Hydrodessus kurti sp. n. (Suriname), Hydrodessus kylei sp. n. (Suriname, Venezuela), Hydrodessus laetus sp. n. (Venezuela), Hydrodessus latotibialis sp. n. (Peru), Hydrodessus maculatus sp. n. (Guyana, Venezuela), Hydrodessus morsus sp. n. (Venezuela), Hydrodessus palus sp. n. (Venezuela), and Hydrodessus tenuatus sp. n. (Suriname). The following new synonyms are established: Hydrodessus fragrans Spangler, 1985 = Hydrodessus biguttatus (Guignot, 1957) syn. n. and Hydrodessus robinae Spangler, 1985 = Hydrodessus octospilus (Guignot, 1957), syn. n. One species is transferred from Hydrodessus to Amarodytes Régimbart, Amarodytes soekhnandanae (Makhan, 1994), comb. n. Habitus photographs (dorsal and lateral) and photos of the ventral surfaces are provided for most species. Line drawings of male and female genitalia and other diagnostic features are also provided along with distribution maps.