On Hypopygus lepturus, a little known dwarf gymnotid fish from South America (Pisces, Cypriniformes, Gymnotoidei)

Hypopygus lepturus Hoedeman, 1062, was hitherto known from the holotype and one paratype only, both imported aquarium specimens. In this paper the type locality of the species is restricted. Additional distributional data from Surinam are given, together with records on the occurrence of H. lepturus in Guyana, Venezuela, Colombia, Brazil, and on the very likely occurrence in Peru. Comparative notes on Steatogenys elegans (Steindachner, 1880) sensu Boulenger, 1898, are added because of the similar appearance of both species. The synonymy of Tateichthys duidae La Monte, 1929, with Steatogenys elegans is established.