Mussel of the

Page last updated
6 May 2021

Mussel of the Month

The May 2021 Mussel of the Month is Haasica balzani. Haasica is a monotypic genus endemic to the Rio Paraguay in South America.

SMF 3792. Rio Apá, State of Saõ Paulo, Brazil (type).

There isn’t much to say about Haasica balzani. The species has been known for more than 100 years from the Paraguay in the Parana-La Plata basin. That it gets its own genus is based entirely on shell characters, and its taxonomic position rests on its overall similarity to Monocondylaea and related genera.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily ETHERIOIDEA Deshayes, 1830
Family MYCETOPODIDAE Gray, 1840
Subfamily MONOCONDYLAEINAE Modell, 1942

Genus Haasica Stand, 1932

Species Haasica balzani (Ihering, 1893)

To find out more about Haasica and the other freshwater mussels of South America, check out:
  • Graf, D.L. & K.S. Cummings. 2021. A ‘big data’ approach to global freshwater mussel diversity (Bivalvia: Unionoida), with an updated checklist of genera and species. Journal of Molluscan Studies 87(1): 1-36.
  • Pereira, D., M.C.D. Mansur, L.D.S. Duarte, A.S. de Oliveira, D.M. Pimpão et al. 2014. Bivalve distribution in hydrographic regions in South America: historical overview and conservation. Hydrobiologia 735: 15-44.
  • Simone, L.R.L. 2006. Land and Freshwater Molluscs of Brazil: An Illustrated Inventory of the Brazilian Malacofauna, Including Neighboring Regions of South America, Respect to the Terrestrial and Freshwater Ecosystems. EGB, Fapesp., Sao Paulo. 390 pp.
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