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Melasma onca (Adams and Angas, 1864)

Diagnostic features

This species is characterised by its slender, straight, evenly spaced axial ribs with a chain of subsutural grain-like nodules.


Melasma onca (Adams and Angas, 1864)

Class Gastropoda

Subclass Caenogastropoda

Order Cerithiomorpha

Superfamily Cerithioidea

Family Thiaridae

Genus Melasma Adams and Angas, 1864 (Type species: Melania (Melasma) onca Adams & Angas, 1864).

Original name: Melania (Melasma) onca Adams and Angas, 1864. Adams, A. and Angas, G. F. (1864). Descriptions of new species of freshwater shells collected by Mr. F.G.Waterhouse during J. McDonald Stuart’s overland journey from Adelaide to the north-west coast of Australia. Proceedings of the Zoological Society of London 1863: 414-418.

Type locality: North Australia, tributary of Adelaide River, Northern Territory.

Biology and ecology

Lives on sandy or stony substrates in the upper and middle sections of seasonal rivers and creeks. Diet consists of detritus and algae. Brood pouch contains a high number (>150) of juveniles in various stages of development.


Tropical wet northern part of the Northern Territory but inland from the coast.

Further reading

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

Glaubrecht, M., Brinkmann, N. & Pöppe, J. (2009). Diversity and disparity ‘down under’: systematics, biogeography and reproductive modes of the ‘marsupial’ freshwater Thiaridae (Caenogastropoda, Cerithioidea) in Australia. Zoosystematics and Evolution 85: 199-275.

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.

Maaß, N. & Glaubrecht, M. 2012. Comparing the reproductive biology of three “marsupial”, eu-viviparous gastropods (Cerithioidea, Thiaridae) from drainages of Australia’s monsoonal north. Zoosystematics and Evolution 88: 293–315.