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Pisidium (Euglesa) etheridgei E.A.Smith, 1883

Diagnostic features

One of the most variable species of Pisidium according to Korniushin, where the variability of shell characters have a geographic pattern with a number of distinct local forms occuring.There is also some controversy as to the affinity of this species with P. casertanum, Korniushin offers a number of character states which separate the two species however the best diagnostic character is the markedly elongate presiphonal suture in P. etheridgei. Some specimens exceed 5 mm in length.

Classification

Pisidium (Euglesa) etheridgei E.A.Smith, 1883

Common name: Pea shell

Class Bivalvia  

Subclass Heteroconchia

Superorder Heterodonta

Order Cardiida

Superfamily Sphaeroidea

Family Sphaeriidae

Genus Pisidium Pfeiffer, 1821

Subgenus Euglesa Jenyns, 1832

Original name: Pisidium etheridgei  E. A. Smith, 1883. Smith, E. A. (1883). On the freshwater shells of Australia.Journal of the Linnean Society 16: 255 - 317.

Type locality: Yan - Yean Reservoir, Plenty district, Victoria.

Synonyms: Australpera mena Iredale, 1943.

Biology and ecology

The number of offspring produced is extremely variable - according to Korniushin - from 1-10 in each demibranch (typically between 4-8). P.etheridgei occurs most frequently in creeks and small rivers. In South Australia and Tasmania it also occurs in lakes and lagoons.

Distribution

Through south-eastern Australia mainly following the Great Dividing Range between southeast Queensland and southeast South Australia, as well as Tasmania.

Further reading

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. (1992). Non-marine Mollusca. Pp. i-xii, 1-408 in W. W. K. Houston. Zoological Catalogue of Australia, 8. Canberra, Australian Government Publishing Service.