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Genus Musculium Link, 1807

Subgenus Sphaerinova Iredale, 1943

Diagnostic features

Shells small (length up to 9 mm, usually 7 to 8 mm) beaks usually slightly shifted posteriorly, not protruding, prodissoconch sometimes separated by growth break line

but never forming bean-shaped cap. Ligament externally visible, elevated in largest specimens. Siphons short, especially their fused part; dorsal retractor muscles of inhalant siphon markedly reduced and scars merged with those of posterior adductors. Nephridium open or closed with broad to narrow and elongate dorsal lobe. Outer demibranch 0.3 to 0.4 height of inner demibranch (depending on stage of development). (Korniushin, 2000).

Both Kuiper (1983) and Korniushin (2000) treated Sphaerinova as a subgenus of Sphaerium by the externally visible ligament and by the peculiar form of the umbo.

Classification

Class Bivalvia

Subclass Heteroconchia

Superorder Heterodonta

Order Cardiida

Superfamily Sphaeroidea

Family Sphaeriidae

Subfamily: Sphaeriinae

Genus Musculium Link, 1807

Subgenus Sphaerinova Iredale, 1943

Type species: Sphaerium macgillivrayi E.A. Smith, 1882

Original reference: Iredale, T. (1943). A basic list of the freshwater Mollusca of Australia. Australian Zoologist 10: 188–230.

Type locality: Penrith, New South Wales.

State of taxonomy

We follow Korniushin (2000).

Biology and ecology

Inhabit almost all types of freshwater habitats including springs, rivers, lakes, ponds, billabongs, waterholes, small creeks, drains and peat bogs. Brood young in multiple brood pouches. Lives in sediment and in weeds.

Distribution

Australia, but may also include taxa from New Zealand, southern Asia and South America.

Notes

Musculium is distinguished from Pisidium based on its larger size, median or nearly median position of the umbo, presence of two tubular siphons, two pairs of retractor muscles by the lower (branchial) siphon, and outer demibranch with two lamellae and multiple brood pouches.

Further reading

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

Korniushin, A. V. (2000). Review of the family Sphaeriidae (Mollusca: Bivalvia) of Australia, with the description of four new species. Records of the Australian Museum 52: 41-102.

Kuiper, J. G. J. (1983). The Sphaeriidae of Australia. Basteria 47: 3-52.

Lamprell, K. & Healy, J. (1998). Bivalves of Australia, volume 2. Leiden, Backhuys Publishers.

Smith, B. J. & Kershaw, R. C. (1979). Field guide to the non-marine Molluscs of South-eastern Australia. Canberra, A.N.U. Press.

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