Fluviopupa gracilis can be separated from F. ramsayi by its elongate-pupoid shell, and the distal end of the penis is longer (not shorter) than the accessory lobe. In F. ramsayi ramsayi, the shell is larger than that of F. ramsayi royana and the inner lip is more closely applied to the parietal wall.
Fluviopupa ramsayi royana (Iredale, 1944)
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Fluviopupa Pilsbry, 1911
Original name: Fluviorissoina royana Iredale, 1944. In Iredale, T. (1944) The land Mollusca of Lord Howe Island. Australian Zoologist 10: 299-334.
Type locality: "Creeks of the Old Settlement" Lord Howe Island. Ponder (1982) recorded this locality as an error and subsequently designated Soldier (or Big) Creek as the type locality.
In small streams and seepages under leaves and stones and on moss and rock surfaces.
In streams flowing east and west of Smoking Tree Ridge, Intermediate Hill and North Hummock, Lord Howe Island.
The Lord Howe Island Fluviopupa species are rather similar in appearance but the different taxa are in distinct geographical locations on Lord Howe Island.
Iredale, T. (1944). The land Mollusca of Lord Howe Island. Australian Zoologist 10: 299-334, pls XVII-XX.
Ponder, W. F. (1982). Hydrobiidae of Lord Howe Island (Mollusca: Gastropoda: Prosobranchia). Australian Journal of Marine and Freshwater Research 33: 89-159.
Zielske, S., Ponder, W. F. & Haase, M. (2017). The enigmatic pattern of long‐distance dispersal of minute freshwater gastropods (Caenogastropoda, Truncatelloidea, Tateidae) across the South Pacific. Journal of Biogeography 44: 195-206.
