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Hyridella (Hyridella) drapeta (Iredale, 1934)

Diagnostic features

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.

The shell reaches about 90 mm in length, and the height/length ratio is less than 50%.

Classification

Hyridella (Hyridella) drapeta (Iredale, 1934)

Common name: Freshwater mussel

Class Bivalvia

Subclass Heteroconchia

Superorder Palaeoheterodonta

Order Unionida

Superfamily Unionoidea

Family Hyriidae

Subfamily: Hyriinae

Genus Hyridella Swainson, 1840

Original name: Hyridunio australis drapeta Iredale, 1934. 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.

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 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).

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 southeast Queensland, New South Wales south to and including the Shoalhaven River but absent from the Nepean River. Present in Victoria in the Gellibrand River.

Further reading

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. 

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

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.

Iredale, T. (1934). The freshwater mussels of Australia. Australian Zoologist 8: 57-78 pls 3-6.

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: consistences and a resolved paradox. Marine and Freshwater Research 44: 609-634.

Johnson, R. I. & Baker, H. B. (1973). The types of Unionacea (Mollusca: Bivalvia) in the Academy of Natural Sciences of Philadelphia. Proceedings of the Academy of Natural Sciences of Philadelphia 125: 145-186.

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.

Jupiter, S. D. & Byrne, M. (1997). Light and scanning electron microscopy of the embryos and glochidia larvae of the Australian freshwater bivalve Hyridella depressa (Hyriidae). Invertebrate Reproduction and Development 32: 177-186.

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.

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.

Shea, M. 1995. Freshwater molluscs of Sydney. Australian Shell News 88:4- 6.

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.