This species is compressed to swollen, its ventral margin being at least slightly rounded, and the shell length reaches about 120 mm with the width/length ratio 58-69%. In the hinge, the pseudocardinal teeth are usually smooth, sometimes grooved. The anterior adductor scar is weak, except in old individuals.
Velesunio ambiguus (Philippi, 1847)
Common name: Balonne freshwater mussel, southern mussel, billabong mussel
Class Bivalvia
Infraclass Heteroconchia
Cohort Palaeoheterodonta
Order Unionida
Superfamily Unionoidea
Family Hyriidae
Subfamily Velesunioninae
Genus Velesunio Iredale, 1934
Original name: Unio ambiguus Philippi, 1847. In Philippi, R. A. (1847). Abbildungen und Beschriebungen neuer oder wenig gekannter Conchylien. Vol. 2. Verlag von Theodor Fischer, Cassel.
Type locality: Australia (as Nova Hollandia).
Synonyms: Unio balonnensis Conrad, 1850; Unio vittatus Lea, 1859; Unio philippianus Küster, 1861; Unio (Alasmodon) evansi A. Adams & Angas 1864; Unio danelli Villa, 1871; Unio jeffreysianus Lea, 1871; Unio protovittatus Hale & Tindale, 1930; Velesunio balonnensis adjunctus Iredale, 1934; Velesunio balonnensis intricatus Iredale, 1934; Velesunio mckeowni Iredale, 1943; Velesunio testatus Iredale, 1943; Velesunio transitus Iredale, 1943.
The last major taxonomic revision of Australian freshwater mussels was by McMichael & Hiscock (1958). Based on the available molecular results, Walker et al. (2014) pointed out that a re-assessment of Australian hyriids is needed.
Shallow burrower in silty sand/mud in streams, billabongs, and slow-flowing rivers. Suspension feeder. Larvae (glochidia) are brooded in the gills of females and, when released, become parasitic on the fins or gills of fish* where they undergo metamorphosis before dropping to the sediment as free-living juvenile mussels. Able to tolerate low oxygen concentrations and long periods out of water.
*Reports of tadpoles being infected by glochidia are erroneous (K. Walker, pers. com. to M. Klunzinger).
Lakes, streams, and rivers of eastern Australia including the Murray-Darling basin, coastal rivers from the Burdekin River in Queensland to the Gawler River in South Australia and the Cooper, Diamantina, and Bulloo rivers of inland Queensland.
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.
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.
Hiscock, I. D. (1950). Shell movements of the freshwater mussel, Hyridella australis Lam. (Lamellibranchiata). Marine and Freshwater Research 1: 259-267 (= V. ambiguus).
Hiscock, I. D. (1951). A note on the life-history of the Australian freshwater mussel, Hyridella australis Lam. Transactions of the Royal Society of South Australia 74: 146-148 (= V. ambiguus).
Hiscock, I. (1953a). Osmoregulation in Australian freshwater mussels (Lamellibranchiata). II. Respiration and its relation to osmoregulation in Hyridella australis (Lam.). Marine and Freshwater Research 4: 330-342 (= V. ambiguus).
Hiscock, I. (1953b). Osmoregulation in Australian freshwater mussels (Lamellibranchiata). I. Water and chloride ion exchange in Hyridella australis (Lam.). Marine and Freshwater Research 4: 317-329 (= V. ambiguus).
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.
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., Markich, S. J. & Brown, P. L. (1993). Comparative accumulation of alkaline-earth metals by two freshwater mussel species from the Nepean River, Australia: consistencies and a resolved paradox. Marine and Freshwater Research 44: 609-634.
Johnson, R. I. (1974). Lea's Unionid types: or, Recent and fossil taxa of Unionacea and Mutelacea introduced by Isaac Lea, including the location of all the extant types. Dept. of Mollusks, Museum of Comparative Zoology, Harvard University, Cambridge, Mass. Special Occasional Publication No. 2: 1-159.
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.
Jones, W. & Walker, K. (1979). Accumulation of iron, manganese, zinc and cadmium by the Australian freshwater mussel Velesunio ambiguus (Phillipi) and its potential as a biological monitor. Marine and Freshwater Research 30: 741-751.
Klunzinger, M. W., Jones, H.A., Humphrey, C. L., Melchior, M., Raadik, T.A., Treby, S., Chandler, L. & Sheldon, F. (2023). Comparative diversity in glochidia of Australasian freshwater mussels. Frontiers in Environmental Science 12: 1305077.
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.
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.
Ponder, W. F., Clark, S. A. & Dallwitz, M. J. (2000). Freshwater and estuarine molluscs: an interactive, illustrated key for New South Wales. Melbourne, CSIRO Publishing.
Shea, M. (1995). Freshwater molluscs of Sydney. Australian Shell News 88: 4-6.
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.
Smith, B. J. & Kershaw, R. C. (1979). Field guide to the non-marine Molluscs of South-eastern Australia. Canberra, A.N.U. Press.
Walker, K. F. (1981a). Ecology of freshwater mussels in the River Murray. Australian Water Council Technical Paper No. 63, 119 pp.
Walker, K. F. (1981b). 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.
