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Velesunio angasi (Sowerby, 1867)

Diagnostic features

The shell is compressed, relatively elongate, the posterior expanded, usually winged; ventral margin usually straight, rarely convex or slightly sinuateshell length up to 90 mm; width/length ratio greater than 55%. The siphons are brick red with dark blotches (cf. V. wilsoni). Anterior adductor scar weakly impressed and the hinge teeth are smooth.


Velesunio angasi (Sowerby, 1867)

Common name: Freshwater mussel

Class Bivalvia

Subclass Heteroconchia

Superorder Palaeoheterodonta

Superfamily Hyrioidea

Family Hyriidae

Subfamily: Velesunioninae

Genus Velesunio Iredale, 1934

Original name: Unio angasi Sowerby,1867. Sowerby, G.B. (1867). Monograph of the genus Unio. Conchologia Iconica 16: plts 55-60.

Type locality: Shangway's River,Northern Territory.

Synonyms: Unio bednalli Tate, 1882; Hyridella (Hyridella) bardwelli Clench, 1934; Aparcthyria hemesa Iredale, 1943; Aparcthyria inspecta Iredale, 1943; Quaesithyria fleckeri Iredale, 1943.

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, billabongs and slow-flowing rivers. Suspension feeder. Reproduction occurs throughout the year. Larvae (glochidia) are brooded in the gills of females and, when released, become parasitic on the gills of fish (see Humphrey and Simpson 1985 for list of species) before dropping to the sediment as young mussels. Able to tolerate low oxygen concentrations and long periods out of water. Recrutment is affected by levels of dissolved oxygen (Humphrey & Simpson 1985). These mussels from 11-35 years and life span is correlated with dissolved oxygen concentrations.

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


This species is widely distributed, occurring from north-eastern Queensland throughout tropical northern Australia, and extending south to the Pilbara region of Western Australia.

Further reading

Allan, J. K. (1934). Pearl from a freshwater mussel, and notes on the occurrence of pearls. The Victorian Naturalist 51: 166-169.

Baker, A. M., Bartlett, C., Bunn, S. E., Goudkamp, K., Sheldon, F. & Hughes, J. M. (2003). Cryptic species and morphological plasticity in longlived bivalves (Unionoida: Hyriidae) from inland Australia. Molecular Ecology 12:2707–2717.

Baker A. M, Sheldon F, Somerville, J., Walker, K. F. & Hughes J. M. (2004). Mitochondrial DNA phylogenetic structuring suggests similarity between two morphologically plastic genera of Australian freshwater mussels (Unionoida: Hyriidae) Molecular Phylogenetics and Evolution 32: 902–912.

Bollhöfer, A., Brazier, J., Humphrey, C., Ryan, B., & Esparon, A. (2011). A study of radium bioaccumulation in freshwater mussels, Velesunio angasi, in the Magela Creek catchment, Northern Territory, Australia. Journal of Environmental Radioactivity 102: 964-974.

Feary, S. (1981). The potential of freshwater mussels as seasonal indicators in archaeology. BA(Hons) thesis, Dept Prehistory and Anthropology, Australian National University, Canberra.

Haas, F. (1969). Superfamilia Unionacea. Das Terreich, 88 (1-10), 1-663.

Hughes, J. M., Baker A. M,  Bartlett, C,  Bunn, S. E, Goudkamp, K. & Somerville, J., 2004. Past and present patterns of connectivity among populations of four cryptic species of freshwater mussels Velesunio spp.(Hyriidae) in central Australia. Molecular Ecology 13, 3197–3212. 

Humphrey, C. L. & Simpson, R. D. (1985). The biology and ecology of Velesunio angasi (Bivalvia: Hyriidae) in the Magela Creek, Northern Territory (4 parts) Open File Record 38, Office of the Supervising Scientist for the Alligator Rivers Region, Canberra, 476 p.

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.

Jeffree, R. A. & Simpson, R. D. (1986). An experimental study of the uptake and loss of Ra-226 by the tissue of the tropical freshwater musselVelesunio angasi (Sowerby) under varying Ca and Mg water concentrations. Hydrobiologia 139: 59-80.

Klunzinger M.W., Morgan D. L., Lymbery A. J., Ebner B. C., Beatty S. J. & Thomson G.L. (2010) Discovery of a host fish for glochidia of Velesunio angasi (Sowerby, 1867) (Bivalvia: Unionoida: Hyriidae) from the Fortescue River, Pilbara, Western Australia Australian Journal of Zoology 58: 263-266.

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. 

Markich, S. J., Jeffree, R. A. & Burke, P. T. (2002). Freshwater bivalve shells as archival indicators of metal pollution from a copper-uranium mine in tropical northern Australia. Environmental Science & Technology 36: 821-832.

Millington, P. J. & Walker, K. F. (1983). Australian freshwater mussel Velesunio ambiguus (Philippi) as a biological monitor for zinc, iron and manganese. Marine and Freshwater Research 34: 873-892.

Ryan, B., Bollhöfer, A., & Martin, P. (2008). Radionuclides and metals in freshwater mussels of the upper South Alligator River, Australia. Journal of environmental radioactivity 9: 509-526.

Sheldon, F. & Walker, K. F. (1989). Effects of hypoxia on oxygen consumption by two species of freshwater mussel (Unionacea: Hyriidae) from the River Murray [Australia]. Australian Journal of Marine and Freshwater Research 40: 491-499.

Simpson, K. N. G. & Blackwood, R. (1973). An Aboriginal cache of freshwater mussels at Lake Victoria, NSW. Memoirs of the National Museum of Victoria 34: 217-218.

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. (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. (1986). The freshwater mussel Velesunio ambiguus as a biomonitor of heavy metals associated with particulate matter. Pp. 175-185 in B. T. Hart. The Role of Particulate Matter in the Transport and Fate of Pollutants. Melbourne, Australia, Water Studies Centre, Chisolm Institute of Technology.

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.

Wirtado, T. H. 1994. Aspects of the biology of Velesunio ambiguus Philippi from a tropical freshwater environment, Ross River, Townsville, Australia. Master of Tropical Science thesis, Department of Zoology, James Cook University of North Queensland.