The shell is very variable in shape and sculpture, some being smooth, others having distinct spiral ridges. The shell can be monocoloured (brown or yellowish) or spirally banded. The aperture is unthickened and simple. Shells often have the large egg capsules attached, coated with white sand grains. Living females are also distinctive in having a lateral pouch on either side of the snout. The operculum is simple, without white smear or pegs on the inner side.
Ascorhis tasmanica (Martens, 1858)
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Ascorhis Ponder & Clark, 1988
Original name: Hydrobia tasmanica Martens, 1858. In Martens, E.C. von (1858). Ueber einige Brakwasserbe wohner aus den Umbebungen Venedigs Archiv für Naturgeschichte 24: 152 - 208.
Type locality: Tasmania (probably near Launceston).
Synonyms: Bythnia victoriae Tenison Woods, 1878; Hydrobia turbinata Petterd, 1889; Assiminea pagodella Hedley, 1902; Rissoa procincta Hedley, 1908; Potamopyrgus ruppiae Hedley, 1912; Webbinella bassensis Parr, 1945.
This very small species lives on aquatic vegetation in the upper parts of estuaries and in coastal lagoons, and it is commonly abundant. It feeds by scraping bacteria and microalgae. The solitary hemispherical, sand-encrusted capsules contain a single egg, and are laid on virtually all substrata, including being frequently attached to the shell of Ascorhis and other co-occurring molluscs. Development is direct.
From mid-Queensland through south-eastern Australia and into South Australia and Tasmania.
This species was long known as Hydrobia buccinoides but this name was changed to Ascorhis victoriae by Ponder & Clark (1988). However, the currently used name was later found to be an earlier name for this species (Ponder, 1997).
A closely related species (A. occidua Ponder & Clark, 1988) is found in south Western Australia.
Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.
Ponder, W. F. (1997). Nomenclatural rectifications in Australian Hydrobiidae. Molluscan Research 18: 67-68.
Ponder, W. F. & Clark, G. A. (1988). A morphological and electrophoretic examination of Hydrobia buccinoides, a variable brackish-water gastropod from temperate Australia (Mollusca: Hydrobiidae). Australian Journal of Zoology 36: 661-689.
Ponder, W. F., Clark, S. A. & Dallwitz, M. J. (2000). Freshwater and estuarine molluscs: an interactive, illustrated key for New South Wales. Melbourne, CSIRO Publishing.
Robinson, K. & Gibbs, P. (1982). A field guide to the common shelled molluscs of New South Wales estuaries. Sydney, Coast and Wetlands Society (as Hydrobia buccinoides).
Smith, B. J. & Kershaw, R. C. (1979). Field guide to the non-marine Molluscs of South-eastern Australia. Canberra, A.N.U. Press (as Hydrobia buccinoides).
Smith, B. J. & Kershaw, R. C. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania (as Hydrobia buccinoides).
