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.
Euglesa etheridgei (E. A. Smith, 1882)
Common name: Pea shell, pea clam, pill clam
Class Bivalvia
Infraclass Heteroconchia
Cohort Heterodonta
Megaorder Neoheterodontei
Order Sphaeriida
Superfamily Sphaerioidea
Family Sphaeriidae
Subfamily: Sphaeriinae
Genus Euglesa Jenyns, 1832 (Type species: Euglesa henslowiana Jenyns, 1832 (= Pisidium personatum Malm, 1855) (also sometimes cited as Tellina pusilla Gmelin, 1791)
Original name: Pisidium etheridgei E. A. Smith, 1882. In Smith, E. A. (1882). On the freshwater shells of Australia. Journal of the Linnean Society 16: 255 - 317.
Type locality: Yan-Yean Reservoir, Plenty District, Victoria.
Synonym: Australpera mena Iredale, 1943.
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. Suspension and deposit feeder.
Through south-eastern Australia mainly following the Great Dividing Range between southeast Queensland and southeast South Australia, and Tasmania.
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.
Lee, T. (2019). Sphaeriidae Deshayes, 1855 (1820). Pp. 197-201 in C. Lydeard & Cummings, K. S. Freshwater Mollusks of the World: a Distribution Atlas. Baltimore, John Hopkins University Press.
Lee, T. & Ó Foighil, D. (2003). Phylogenetic structure of the Sphaeriinae, a global clade of freshwater bivalve molluscs, inferred from nuclear (ITS-1) and mitochondrial (16S) ribosomal gene sequences. Zoological Journal of the Linnean Society 137: 245-260.
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.
