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Striadorbis Ponder and Avern, 2000

Diagnostic features

Shell differs from Glacidorbis in being planispiral, and in having spiral microsculpture on the latter part of protoconch and (at least) the early teleoconch. A mid-dorsal and mid-ventral spiral keel may be present. Protoconch with pustules in initial part, teleoconch whorls keeled or evenly rounded. Operculum circular with overlapping whorls, a central nucleus and external pustules.

Anatomy differs from Glacidorbis in that the mantle cavity is longer and narrower and the rectum longer; the mantle lobe is shorter; the vagina is large and contains a prominent internal fold; and the penis is narrower and the praeputium contains fewer glandular protuberances that are rounded distally, not disk-like as in G. hedleyi. Striadorbis apparently does not brood embyos.

Classification

Class Gastropoda

Subclass Heterobranchia

Superfamily Glacidorboidea

Family Glacidorbidae

Genus Striadorbis Ponder and Avern, 2000

Type species: Valvata(?) pedderi Smith, 1973.

Original reference: Ponder, W. F. and. Avern, G. J. (2000). The Glacidorbidae (Mollusca: Gastropoda: (Heterobranchia) of Australia. Records of the Australian Museum 52: 307–353. 

Type locality: In small hole in plain just south of Lake Edgar (now drowned as part of Lake Pedder) Tasmania.

Biology and ecology

Lives in rivers, streams, lakes, seeps and bogs. Found amongst weed, sedges, rushes and roots, rocks, gravel and cobbles, and muddy, silty or sandy substrates. Feeding biology unknown, possibly carnivorous. Like Glacidorbis hedleyi, Striadorbis pedderi appears to be a protandrous hermaphrodite but, unlike G. hedleyi, there is no evidence  that brooding occurs in S. pedderi.

Distribution

Striadorbis has an unusual disjunct range - two species are found in the western and northern half of the east coast of Tasmania and one species is  found in western Victoria.

Unamed species probably referrable to this genus are known from SW Australia and another from the Grampians in Victoria.

Further reading

Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.

Meier-Brook, C. & Smith, B. J. (1976). Glacidorbis Iredale 1943, a genus of freshwater prosobranchs with a Tasmanian-Southeast Australian-South Andean distribution. Archiv Für Molluskenkunde 106: 191-198.

Ponder, W. F. (1986b). Glacidorbidae (Glacidorbacea: Basommatophora), a new family and superfamily of operculate freshwater gastropods. Zoological Journal of the Linnean Society 87: 53-83.

Ponder, W. F. & Avern, G. J. (2000). The Glacidorbidae (Mollusca: Gastropoda: Heterobranchia) of Australia. Records of the Australian Museum 52: 307-353.

Smith, B. J. and Kershaw, R. C. (1979). Field guide to the non-marine molluscs of south eastern Australia. Australian National University Press, Canberra, Australia.

Smith, B. J. & Kershaw, R. C. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania.

Rumi, A., Gutiérrez Gregoric, D. E., Landoni, N., Cárdenas Mancilla, J., Gordillo, S., Gonzalez, J., & Alvarez, D. (2015). Glacidorbidae (Gastropoda: Heterobranchia) in South America: revision and description of a new genus and three new species from Patagonia. Molluscan Research 35: 143-152.