A taxonomic revision of South African Sharphydrus, with the description of two new species (Coleoptera: Dytiscidae: Bidessini)

Sharphydrus Omer-Cooper, 1958 is one of two endemic bidessine genera currently recognised from South Africa. Here Sharphydrus brincki sp. nov. and Sharphydrus kamiesbergensis sp. nov. are described from the Cederberg and Gydopas areas of the Western Cape, and the high Kamiesberg of the Northern Cape respectively, doubling the known species of this genus. It is shown that S. brincki sp. nov. has been included under S. capensis (Omer-Cooper, 1955) in the past, but that these are quite distinct taxa, differing in the extent of their elytral keels and male genitalia. Sharphydrus species are inhabitants of pools in seasonally fluctuating rivers, the new species described here occurring in areas which are somewhat transitional between fynbos and karoo biomes. An updated key is presented to Sharphydrus species, together with data on the distribution and ecology of known species, and a discussion of the status of the genus within the Bidessini.