Hydrocyrius Spinola, 1850a: 49. Type species by monotypy (Spinola, 1850: 106): Hydrocyrius colombiae Spinola, 1850.
Ilyotrephes Stål, 1854b: 264 (syn. Gerstaecker, 1856: 293). Type species by subsequent monotypy (Stål, 1855a: 46): Ilyotrephes herculeus Stål, 1855 (= Hydrocyrius colombiae Spinola, 1850).
Diplonychus (non Laporte, 1833): Torre Bueno, 1907: 333. Misidentification.
Poissonia Brown, 1948a: 109 (syn. Lauck & Menke, 1961: 649). Type species by original designation: Poissonia longifemorata Brown, 1948, Botswana.
Paracyrius Poisson, 1949a: 10 (as subgenus of Hydrocyrius; syn. Lauck & Menke, 1961: 649). Type species by monotypy: Hydrocyrius rectus Mayr, 1863, Sierra Leone.