 George M. Thomson described a second species in 1885, as "Pherusa coerulea" (now "Paraleptamphopus caeruleus").Although no other species have yet been formally described, it is thought that many more undescribed species exist.In 1882, Charles Chilton collected specimens of "P. subterraneus" from groundwater at his farm near Eyreton, Canterbury, and later obtained specimens from various depths in Lincoln, Winchester and St. Albans.