Hydrachna Müller, 1776

Synonyms: Limnohydrachna Thor, 1916, Monohydrachna Thor, 1916, Odontohydrachna Thor, 1916, Schizohydrachna Thor, 1916, Scutohydrachna K. Viets, 1933, Tetrahydrachna Lundblad, 1934, Chitohydrachna Habeeb, 1966, Hymenohydrachna Wainstein, 1966, Microhydrachna Wainstein, 1976, Piersigihydrachna Wainstein, 1976, Thorihydrachna Wainstein 1976 (K. O. Viets, 1987); Anohydrachna Thor, 1916 (nov. syn.), Diplohydrachna Thor, 1916 (nov. syn.), Rhabdohydrachna K. Viets, 1931 (nov. syn.).