This species differs from the other NSW species of Hyridella (except H. depressa) in having delicate beak sculpture. The shell is moderately elongate, oval, posteriorly evenly rounded and the posterior ridge is broad but weak and flattened while the dorsal margin is weakly winged. The beaks do not project above the dorsal margin and the ventral margin is straight to weakly concave. There is also a diagnostic sulcation between the anterior and posterior sections of the shell. The periostracum varies from steel grey to brown; it is never glossy and black as in Hyridella australis. Glochidia larval teeth are bifurcated.
The shell reaches about 90 mm in length, and the height/length ratio is less than 50%.
Hyridella drapeta (Iredale, 1934)
Common name: Freshwater mussel
Class Bivalvia
Infraclass Heteroconchia
Cohort Palaeoheterodonta
Order Unionida
Superfamily Unionoidea
Family Hyriidae
Subfamily Hyriinae
Genus Hyridella Swainson, 1840
Original name: Hyridunio australis drapeta Iredale, 1934. In Iredale, T. (1934). The freshwater mussels of Australia. Australian Zoologist 8: 57-78 pls 3-6.
Type locality: Brisbane River, Queensland.
Synonyms: Hyridunio australis orion Iredale, 1934; Hyridunio renutus Iredale, 1934; Hyridunio australis casus Iredale, 1943.
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 reassessment of Australian hyriids is needed and one is now in progress.
Shallow burrower in silty sand/mud in streams, billabongs, 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. Releases glochidia from August to autumn. Parasitic on a wide range of freshwater fish including introduced mosquito fish (Gambusia holbrooki).
Coastal rivers and streams of southeast Queensland, New South Wales south to and including the Shoalhaven River but absent from the Nepean River. Also present in Victoria (in the Gellibrand River).
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.
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Byrne, M. & Vesk, P. A. (1997). Microanalysis of elements in granules in Hyridella depressa (Bivalvia): Multivariate analysis and biomonitoring potential. Australasian Journal of Ecotoxicology 2: 91-97.
Cotton, B.C. & Gabriel, C.J. (1932). Australian Unionidae. Proceedings of the Royal Society of Victoria (ns) 44: 155-160.
Haas, F. (1912). Die Unioniden. pp. 113-136 in Küster, H.C., Martini, F.W. & Chemnitz, J.H. (eds) Systematiches Conchylien-Cabinet. Nürnberg : Bauer & Raspe Bd 9 Abt. 2.
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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, H. A., Simpson, R. D. & Humphrey, C. L. (1986). The reproductive cycles and glochidia of fresh-water mussels (Bivalvia: Hyriidae) of the Macleay River, Northern New South Wales, Australia. Malacologia 27: 185-202.
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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 + 319 plates.
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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. (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.
