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Westralunio carteri Iredale,1934

Diagnostic features

Shell medium sized, oblong to ovate, solid to thin valves, sculpture of radial growth lines, umbos smooth but are often eroded, thick black periostracum, interior of valves nacreous bluish to bronze to white,  hinge teeth with very strong grooved (serrated) pseudocardinal teeth,  anterior retractor muscle scars deeply impressed.

Anatomy: Supra anal opening absent, larvae are brooded in the inner pair of demibranchs, inhalant and exhalant siphons are short but prominent and formed by the mantle edge which is open ventrally and fused posteriorly, branchial siphon larger than anal siphon bearing a variable number of prominent papillae and heavily pigmented.

The Australian genera of freshwater mussels are distinguished by the following shell characters (note that all are subject to erosion with age, depending on the local environment):-

Hyridella. Beak of young specimens at least sculptured with V-shaped ridges; shell quadrate to elongate (ratio of maximum height of shell to its length >50%), not markedly winged. Hinge strong with grooved pseudocardinal teeth and simple 'lateral' teeth. Shell surface (other than beaks) more-or-less smooth except for concentric growth lines.

Velesunio. Beaks smooth, shell can be rather thick, rounded in outline (ratio of maximum height of shell to its length >50%), often inflated, hinge lamellar, usually simple (rarely serrated). Shell surface with concentric growth lines only.

Alathyria. Shell typically large, elongate-ovate (ratio of maximum height of shell to its length >50%), often distinctly winged, thick, hinge usually with heavy, pseudocardinal teeth grooved, 'lateral' teeth smooth. Shell surface more-or-less smooth, with concentric growth lines only.

Cucumerunio. Shell very elongate (ratio of maximum height of shell to its length <40%), beaks sculptured with V-shaped ridges; rest of shell surface with conspicuous nodules or ridges. Hinge strong, pseudocardinal teeth grooved.

Lortiella. Shell elongate (ratio of maximum height of shell to its length <45%), winged posteriorly, hinge simple, not well developed. Beaks smooth and shell surface with concentric growth lines only. Found in NW Australia.

Westralunio. Shell more or less oblong (ratio of maximum height of shell to its length >50%). Pseudocardinal teeth erect, strongly serrated, shell small (less than 70 mm in length). Beaks smooth, shell rather thick, with concentric growth lines only. Restricted to SW Australia.

Classification

Westralunio carteri Iredale, 1934

Class Bivalvia

Subclass Heteroconchia

Superorder Palaeoheterodonta

Order Unionida

Superfamily Unionoidea

Family Hyriidae

Subfamily: Velesunioninae

Genus Westralunio Iredale,1934 (Type species: Westalunio ambiguus carteri  Iredale,1934)

Original name: Westalunio ambiguus carteri  Iredale,1934. Iredale, T. (1934). The freshwater mussels of Australia. Australian Zoologist 8: 57-78.

Type locality: Victoria Reservoir in the Darling Ranges,12 miles east of Perth, Western Australia.

Synonyms: Centralhyria angasi subjecta 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 silty sand/mud in 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.

Mainly live in flowing freshwater rivers, streams and water supply reservoirs. Infaunal, living two thirds to almost fully buried in sand and sediment. Suspension feeders. Dioecious. Brood young in marsupia in the inner pair of demibranchs. Larvae parasitic, using fish as hosts and dispersal agents.

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 of south-western Australia.

Further reading

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

Haas, F. (1969) Superfamilia Unionacea (in) Das Terreich, Lieferung 88, de Gruyter and Co. Berlin.

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.

Iredale, T. (1943). A basic list of the fresh water Mollusca of Australia. Australian Zoologist 10: 188-230.

Klunzinger, M.W., Beatty, S.J., Morgan, D.L., Thomson, G.J. & Lymbery, A.J. (2012). Glochidia ecology in wild fish populations and laboratory determination of competent host fishes for an endemic freshwater mussel of south-western Australia. Australian Journal of Zoology 60: 26-36.

Klunzinger, M. W., Beatty, S. J., Morgan, D. L., & Lymbery, A. J. (2012). Distribution of Westralunio carteri Iredale, 1934 (Bivalvia: Unionoida: Hyriidae) on the south coast of south-western Australia, including new records of the species. Journal of the Royal Society of Western Australia 95: 77-81.

Klunzinger, M. W., Thomson, G. J., Beatty, S. J., Morgan, D. L., & Lymbery, A. J. (2013). Morphological and morphometrical description of the glochidia of Westralunio carteri Iredale, 1934 (Bivalvia: Unionoida: Hyriidae).Molluscan Research 33: 104-109.

Klunzinger M. W., Beatty S.J., Morgan D.L., Lymbery A. J. & Haag ,W.R. (2014). Age and growth in the Australian freshwater mussel, Westralunio carteri, with an evaluation of the fluorochrome calcein for validating the assumption of annulus formation. Freshwater Science  33:1127-1135.

Klunzinger M. W., Beatty S. J., Morgan D. L., Pinder  A. M. & Lymbery A. J. (2015). Range decline and conservation status of Westralunio carteri Iredale, 1934 (Bivalvia:Hyriidae) from south-western Australia Australian Journal of Zoology 63: 127-135.

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.

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.

Walker, K. F. (2004). A guide to the provisional identification of the freshwater mussels (Unionoida) of Australasia. Albury, Murray Darling Freshwater Research Centre.

Walker, K. F., Byrne, M., Hickey, C. W. & Roper, D. S. (2001). Freshwater Mussels (Hyriidae) of Australasia. Pp. 5-31 in G. Bauer & Wächtler, K. Ecology and Evolution of the Freshwater Mussels Unionoida. Ecological Studies. Berlin, Springer-Verlag.

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.

Zieritz, A., Sartori, A. F. & Klunzinger, M. W. (2013). Morphological evidence shows that not all Velesunioninae have smooth umbos. Journal of Molluscan Studies 79: 277–282.