Shell small 3-12 mm in length, broadly ovate to narrowly conical, spire outlines and whorls convex, sutures impressed, simple. Protoconch dome-shaped, of 1.3 whorls, sculptured with minute, hollow blisters which, when worn, leave surface pitted teleoconch of 3 whorls, smooth except for axial growth lines and sometimes with periostracal ornament of spines and processes (in P. antipodarum). Aperture large to medium, oval, outer lip slightly prosocline; inner lip somewhat thickened, attached to parietal wall at all but anterior end in some specimens separated by narrow groove in others. Colour yellowish brown to orange-brown or brown, aperture white to yellow, colour imparted mainly by periostracum. Operculum thin, horny, paucispiral, nucleus eccentric, without calcareous smear.
Genus Potamopyrgus Stimpson, 1865
Type species: Melania corolla Gould, 1847 ( = Amnicola antipodarum Gray, 1843)
Original reference: Stimpson, W. (1865). Diagnoses of newly discovered genera of gastropods, belonging to the sub-fam. Hydrobiinae, of the family Rissoidae. Am. J. Conchol. 1, 524.
Type locality: New Zealand.
Synonym: Huttonia Johnston, 1891
The Lord Howe Island ‘P’. oscitans appears to be restricted to vertical or nearly vertical rock faces under flowing, permanent water. The introduced P. antipodarum lives in polluted and unpolluted streams, lakes and drains in urban and rural areas. It lives on most kinds of substrate, including the inside of water pipes and water reticulation systems. Members of the genus feed on bacteria, microscopic algae, diatoms and, possibly, decaying vegetation. P. antipodarum is ovoviviparous,and parthenogenic, and has become a pest wherever it has been introduced, often reaching enormous population densities.
The introduction to Europe, North America, Asia and Australia by Potamopyrgus antipodarum is well documented in the literature. In Europe the species had been named Potamopyrgus jenkinsi (Smith). It remains to be seen whether the Lord Howe Island 'Potamopyrgus' oscitans actually belongs to this genus.
Beesley, P. L., Ross, G. J. B. and Wells, A. (Eds). 1998. Mollusca: The Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing, Melbourne. Part A. Pp. i-xvi,1-563, Part B i-viii, 565-1234.
Haase, M. (2008). The radiation of hydrobiid gastropods in New Zealand: a revision including the description of new species based on morphology and mtDNA sequence information. Systematics and Biodiversity 6: 99-159.
Ponder, W. F. (1988b). Potamopyrgus antipodarum: a molluscan colonizer of Europe and Australia. Journal of Molluscan Studies 54: 271-285.
Schreiber, E. S. G., Glaister, A., Quinn, G. P. & Lake, P. S. (1998). Life history and population dynamics of the exotic snail Potamopyrgus antipodarum (Prosobranchia: Hydrobiidae) in Lake Purrumbete, Victoria, Australia. Marine and Freshwater Research 49: 73-78.
Wallace, C. (1978). Notes on the distribution of sex and shell characters in some Australian populations of Potamopyrgus (Gastropoda: Hydrobiidae). Journal of the Malacological Society of Australia 4: 71-76.
Wallace, C. (1980). Sex in Potamopyrgus (abstract). Journal of the Malacological Society of Australia 4: 263.
Wallace, C. (1992). Parthenogenesis, sex and chromosomes in Potamopyrgus. Journal of Molluscan Studies 58: 93-107.
Winterbourn, M. (1970). The New Zealand species of Potamopyrgus (Gastropoda : Hydrobiidae). Malacologia 10: 283-321.
Winterbourn, M. J. (1969). Water temperature as a factor limiting the distribution of Potamopyrgus antipodum (Gastropoda-Prosobranchia) in the New Zealand thermal region. New Zealand Journal of Marine and Freshwater Research 3: 453-458.
Winterbourn, M. J. (1972). Morphological variation of Potamopyrgus jenkinsi (Smith) from England and a comparison with the New Zealand species, Potamopyrgus antipodarum (Gray). Proceedings of the Malacological Society of London 40: 133-145.