 Later, Horton H. Hobbs, Jr. realised that the troglobitic shrimp he had described in 1973 from Oaxaca, Mexico as "Alpheopsis stygicola", also belonged to the genus, and in 1991, A. J. Bruce described a new species from Australia, further expanding the genus' geographical range.It is now thought to represent a relict taxon from the Tethys Sea.The following species are currently accepted as valid