Mussel of the

Page last updated
7 July 2022

Mussel of the Month

The July 2022 Mussel of the Month is Castalia martensi. Castalia is a genus of 13 species in South America.

SMF 3785. Rio Camaguam [Rio Camaquã], Rio Grande do Sul, Brazil. (type)

It was 16 years ago this month when we last turned the Mussel of the Month to the Neotropical Hyriidae genus Castalia. In our first global checklist back in 2007, we listed 8 species in that genus, but now we list 13 (Graf & Cummings, 2007, 2021). The difference reflects less any new revisionary work and more reversal of the lumping of Simone (2006). Historically, the species of Castalia had been more split, as exemplified by Haas (1969).* More recently, the species richness of the genus has been estimated to be higher (Pereira et al., 2014).

Hopefully, we will see some more phylogenetic and revisionary work that investigates the species of Castalia. As can be seen from the cladomics page for the genus on this web site, as of this typing, only a few species of Castalia have been analyzed in phylogenetic analyses, and the genus is often not recovered as monophyletic (e.g., Santos-Neto et al., 2016).

Castalia classification
Three classifications of Castalia.

Traditionally, the current species of Castalia have been divided among two genera, Castalia s.s. and Castalina, based on the shapes of their shells and the extent to which the “radial” sculpture covers the valves. Castalia martensi is the type of Castalina, so if future revisionary work reinstates the old generic system, this Mussel of the Month post will be ready to represent it!

* When Fritz Haas was splitting, he could be the splitting-est splitter to ever split, but — in fairness — at other times, we he could lump like he was paid by the synonym.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily HYRIOIDEA Swainson, 1840
Family HYRIIDAE s.s.
Subfamily HYRIINAE s.s.
Tribe CASTALIINI Morretes, 1949

Genus Castalia Lamarck, 1819
[= Castalina Ihering, 1891]

Species Castalia martensi (Ihering, 1891)

To find out more about Castalia, Castalina, and the classification of South American freshwater mussels, check out:
  • Graf, D.L. & K.S. Cummings. 2007. Review of the systematics and global diversity of freshwater mussel species (Bivalvia: Unionoida). Journal of Molluscan Studies 73: 291-314.
  • 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): eyaa034 (36 pp.).
  • Haas, F. 1969. Superfamilia Unionacea. Das Tierreich, Leif. 88. Walter de Gruyter and Co., Berlin. 663 pp.
  • 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.
  • Santos-Neto, G. da Cruz, C.R. Beasley, H. Schneider, D.M. Pimpão, W.R. Hoeh et al. 2016. Genetic relationships among freshwater mussel species from fifteen Amazonian rivers and inferences on the evolution of the Hyriidae (Mollusca: Bivalvia: Unionida). Molecular Phylogenetics and Evolution 100: 148-159.
  • 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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