The shell is compressed, relatively elongate, the posterior expanded, usually winged; ventral margin usually straight, rarely convex or slightly sinuate; shell 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: Angas's freshwater mussel
Class Bivalvia
Infraclass Heteroconchia
Cohort Palaeoheterodonta
Order Unionida
Superfamily Unionoidea
Family Hyriidae
Subfamily Velesunioninae
Genus Velesunio Iredale, 1934
Original name: Unio angasi Sowerby,1867. In Sowerby, G.B. (1867). Monograph of the genus Unio. Conchologia Iconica 16: plts 55-60.
Type locality: Strangways 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.
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. Reproduction occurs throughout the year. Larvae (glochidia) are brooded in the marsupia 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. Recruitment is affected by levels of dissolved oxygen (Humphrey & Simpson 1985). These mussels may live for at least 11-35 years and life span is correlated with dissolved oxygen concentrations.
This species is widely distributed, occurring from north-eastern Queensland throughout tropical northern Australia, and extending south to the Pilbara region of Western Australia.
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Kleinhenz, L. S., Nugegoda, D., Trenfield, M. A., van Dam, R. A., Humphrey, C. L., Mooney, T. J. & Harford, A. J. (2019). Acute and chronic toxicity of magnesium to the early life stages of two tropical freshwater mussel species. Ecotoxicology and Environmental Safety 184: 109638.
Kleinhenz, L. S., Humphrey, C. L., Mooney, T. J., Trenfield, M. A., van Dam, R. A., Nugegoda, D. & Harford, A. J. (2019). Chronic ammonia toxicity to juveniles of 2 tropical Australian freshwater mussels (Velesunio spp.): Toxicity test optimization and implications for water quality guideline values. Environmental Toxicology and Chemistry 38: 841-851.
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