Mussel of the

Page last updated
6 March 2016

Mussel of the Month

The March 2016 Mussel of the Month is Hyridella glenelgensis. Hyridella is a genus of 7 species found in Australia, New Guinea and the Solomon Islands.

Hyridella glenelgensis
top: MCZ 190265. Port Fairy, Victoria, Australia.
bottom: AMS 127044. Glenelg River, Victoria, Australia

Back in 2009, we first shared Hyridella through this venue. We are bringing that genus back with H. glenelgensis to honor our colleague, the late Dr. Keith Walker of the University of Adelaide, South Australia. The following was offered by our friend and collaborator, Dr. Hugh Jones of Sydney, Australia

The Glenelg mussel is unusual among the Australian Hyriidae in that most of the surface of the adult shell is strongly sculptured with v-shaped ridges extending outwards from the umbos. It is restricted to a few, small streams in the lower Glenelg River catchment in the southern edge of Australia and is federally listed as critically endangered. The decline in H. glenelgensis is thought to be linked to increasing salinization of rivers resulting from land use change, indirect effects of forestry and the direct impacts of domestic livestock access to rivers. Genetic studies are currently underway to resolve the taxonomic status of H. glenelgensis with respect to its congener, H. narracanensis.

Dr. Keith Walker was a university professor at the University of Adelaide since 1975, focussed on improving understanding the ecology of the River Murray, especially the impact of river regulation. Keith had a major interest in freshwater molluscs and made a valuable contribution to knowledge of the two dominant freshwater mussels in the Murray River, Alathyria jacksoni and Velesunio ambiguus. He also observed the decline in gastropods in the river, notably the viviparid Notopala hanleyi. I recall Keith pointing out the many shells of this “extinct” mollusc littering the banks and floodplain of the lower Murray. Then one day, an irrigator arrived in his office with a box full of shells of this species, claiming that they were clogging his irrigation pipes and wanting to know how he could get rid of them! This sparked several years of research on this species resulting in its listing on federal and state threatened species legislation. Dr. Walker was also instrumental in the rediscovery and federal listing of Hyridella glenelgensis as critically endangered and undertook basic research into the biology of this species. He was currently contributing to research into its species status.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Family HYRIIDAE Swainson, 1840
Subfamily HYRIINAE s.s.
Tribe HYRIDELLINI McMichael, 1956 (1934)

Genus Hyridella Swainson, 1840

Species Hyridella glenelgensis (Dennant, 1898)

To find out more about Hyridella and Keith Walker's work on Australian freshwater mollusks, check out:
  • Playford, T.J., and Walker, K.F. 2008. Status of the endangered Glenelg River mussel Hyridella glenelgensis (Dennant 1898) (Unionoida: Hyriidae) in Australia. Aquatic Conservation: Marine and Freshwater Ecosystems 18(5): 679-691.
  • Sheldon, F., and Walker, K.F. 1993. Pipelines as a refuge for freshwater snails. Regulated Rivers: Research & Management 8(3): 295-299.
  • Walker, K.F. 1981. Ecology of Freshwater Mussels in the River Murray. Australian Water Resources Council Technical Paper No. 63. Australian Government Publishing Service, Canberra.
  • Walker, K.F. 1981. The distribution of freshwater mussels (Mollusca: Pelecypoda) in the Australian zoogeographic region. In Ecological Biogeography of Australia. Edited by A. Keast. Dr W. Junk, The Hague. pp. 1233-1249.
  • Walker, K.F. 1998. Molluscs of inland waters. In Mollusca: The Southern Synthesis. Fauna of Australia. Edited by P.L. Beesley, G.J.B. Ross and A. Wells. CSIRO Publishing, Melbourne. pp. 59-65.
  • Walker, K.F., Byrne, M., Hickey, C.W., and Roper, D.S. 2001. Freshwater mussels (Hyriidae) of Australasia. In Ecological Studies. Ecology and evolution of the freshwater mussels Unionoida. Edited by G. Bauer and K. Wächtler. Springer, Berlin. pp. 5-31.
  • Walker, K.F., Jones, H.A., and Klunzinger, M.W. 2014. Bivalves in a bottleneck: taxonomy, phylogeography and conservation of freshwater mussels (Bivalvia: Unionoida) in Australasia. Hydrobiologia 735: 61-79.
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