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Hyridella (Hyridella) narracanensis (Cotton & Gabriel, 1932)

Diagnostic features

This small (maximum length about 60 mm) species has an 'amygdaloid' (i.e., almond) shape and a very strong hinge. It is not markedly winged posteriorly, but the posterior end is pointed and ridged. The strong beak sculpure does not extend onto the adult shell.

Classification

Hyridella (Hyridella) narracanensis (Cotton & Gabriel, 1932)

Common name: Freshwater mussel

Class Bivalvia

Subclass Heteroconchia

Superorder Palaeoheterodonta

Order Unionida

Superfamily Unionoidea

Family Hyriidae

Subfamily: Hyriinae

Genus Hyridella Swainson, 1840

Original name: Propehyridella narracanensis Cotton & Gabriel, 1932. Cotton, B. C. & Gabriel, C. J. (1932). Australian Unionidae. Proceedings of the Royal Society of Victoria 44: 155-160.

Type locality: Narracan River, Thorpdale,Gippsland,Victoria.

Synonym: Rugoshyria depressa sodalis Iredale, 1934.

State of taxonomy

The last major taxonomic revision of Australian freshwater mussels was by McMichael and Hiscock (1958).

Based on the available molecular results, Walker et al. (2014) pointed out that a re-assessment of Australian hyriids is needed.

Biology and ecology

Shallow burrower in sand/mud in permanent stable streams and rivers. Suspension feeder. Larvae (glochidia) are brooded in the gills and, when released, become parasitic on fish gills before dropping to the sediment as young mussels.

Additional information on the biology and ecology of members of this family can be found in Fauna of Australia, vol. 5A, p. 296-298.

Distribution

Coastal rivers and streams in Victoria west of south Gippsland, the Millicent Coast of South Australia and the Bobbyalla and Tamar rivers of northern Tasmania with the former the only known extant populations.

Notes

This species has declined in its distribution and and is listed as threatened on the IUCN Red List.

Further reading

Atkins, L. (1979). Observations on the glochidial stage of the freshwater mussel Hyridella (Hyridella) drapeta (Iredale)(Mollusca: Pelecypoda). Marine and Freshwater Research 30: 411-416. 

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

Cotton, B.C. & Gabriel, C.J. (1932). Australian Unionidae. Proceedings of the Royal Society of Victoria (ns) 44: 155-160.

Jones, H. A. & Byrne, M. (2014). Changes in the distributions of freshwater mussels (Unionoida: Hyriidae) in coastal southeastern Australia and implications for their conservation status. Aquatic Conservation: Marine and Freshwater Ecosystems 24: 203-217.

Iredale, T. (1934). The freshwater mussels of Australia. Australian Zoologist 8: 57-78 pls 3-6.

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.

Smith, B. J. (2005). Significant range extension for the freshwater mussel Hyridella (Hyridella) narracanensis in Tasmania. The Tasmanian Naturalist 127: 49-53.

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.

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

McMichael, D. F. & Hiscock, I. D. (1958). A monograph of the freshwater mussels (Mollusca: Pelecypoda) of the Australian region. Australian Journal of Marine and Freshwater Research 9: 372-508 + 319 plates.

Walker, K. F. (1981). The distribution of freshwater mussels (Mollusca: Pelecypoda) in the Australian zoogeographic region. Pp. 1233-1249 in A. Keast. Ecological Biogeography of Australia. The Hague, Dr W. Junk.

Walker, K. F., Jones, H. A. &  Klunzinger, M. W. (2014). Bivalves in a bottleneck: taxonomy, phylogeography and conservation of freshwater mussels (Bivalvia: Unionoida) in Australasia. Hydrobiologia 735:61–79.