Abstract
With 257 species known worldwide (Hansen, 1999; Short & Hebauer, 2006; Short & Fikáček, 2011; Gentili, 2012; Jia et al., 2013a; Jia et al, 2013b; Gentili, 2014), Laccobius Erichson is one of the most diverse genera of Hydrophilidae, most species having a relatively uniform convex, rounded appearance. To date only 26 species are known from sub-Saharan Africa (Gentili, 1981; Hebauer, 2006), 11 of which have been reported from southern Africa (Staals & DeMoor, 2007), five being endemic to the region. Southern African species to date all belong to the subgenera Microlaccobius Gentili and Hydroxenus Wollaston. Here we describe a new species of Hydroxenus from the Western Cape province of South Africa. The new species is morphologically closest to Laccobius caffer Boheman, a species widely distributed from western and central Africa to South Africa and Namibia, but the two can be distinguished readily on both external morphology and male genitalia. The new species was collected in marginal gravels of a drying river bed, a typical habitat for many Laccobius, and one which would repay further study in other parts of southern Africa, whose water beetle fauna remains incompletely known.