Fluviopupa gracilis is separated from F. ramsayi in having an elongate-pupoid shell and the distal end of the penis is longer (not shorter) than the accessory lobe. In F. gracilis gracilis the mantle is darkly pigmented and the pupoid shell has 3.7 to 4 whorls which have impressed sutures and the operculum has a small white smear on the inner side.
Fluviopupa gracilis gracilis (Iredale, 1944)
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Fluviopupa Pilsbry, 1911
Original name: Pupidrobia gracilis Iredale, 1944. In Iredale,T. (1944) The land Mollusca of Lord Howe Island Australian Zoologist 10: 299-334.
Type locality: Little Slope, Lord Howe Island.
Found in small creeks and seepage pools on rock surfaces.
Little Slope, western side of Mt. Gower, 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.
