Mussel of the

Page last updated
4 March 2020

Mussel of the Month

The March 2020 Mussel of the Month is Indonaia caerulea. Indonaia is a genus of 14 species found from India east to Thailand.

USNM 85193. Bengal, India (type).

Back in 2007, when we published our first global checklist of freshwater mussels (Graf & Cummings, 2007), we didn’t treat the genus name Indonaia as valid. Instead, we followed the going taxonomy of Subba Rao (1989), Ramakrishna & Dey (2007) and others to lump those species under Parreysia (Radiatula). Then (as now) we were not fans of subgenera, but the concept of the genus Parreysia at the time was unwieldy, and we made an exception to acknowledge that other contemporary classifications recognized Radiatula as a distinct genus (e.g., Nesemann et al., 2007). Nowadays, with the availability of molecular phylogenies, the tendency has been to recognize the few species of Indonaia that have been analyzed as a clade distinct from the rest of Radiatula (Bolotov et al., 2017; Konopleva et al., 2019). And so, here we are with Inodonaia caerulea, the type species of the genus.

Among the difficulties of studying freshwater mussel systematics is making sense of the history of name changes and re-classifications over the decades and centuries. The rules of the ICZN require us to care about priority and first revisers, and as such the past is our business. Fortunately, the MUSSEL Project Database is available to assist in those endeavors, and we are pleased to announce a new feature of available on this website. For each and every freshwater bivalve name (valid or not), we provide the history of citations we have captured from the literature.

For example, on the specimens page for the valid species Indonaia caerulea, we not only provide a map of specimen records but also the taxonomic history since 2007. That history documents the various names and combinations used since our 2007 checklist for this species and all of its synonyms, and links are provided to the individual references.

By clicking the link to the nominal species, you can find the synonymy for Indonaia caerulea. Typically, the nomina in a synonymy are listed strictly chronologically. On our site, we list the names by how recently they were regarded as valid. This moves the most interesting names to the top of what can be a long list (e.g., the synonymy of Anodonta anatina). For each name we provide a complete cresonymy — the history of name usage for that nomen.

So there it is. For any freshwater bivalve species on our web site, you can see not only how we classify it and circumscribe the often-numerous synonyms. And, you get the taxonomy that is the basis for our usage as well as potential alternative classifications. We don’t know of another mollusk database or any source since Simpson (1900) that provides such comprehensive taxonomic data on freshwater mussels!


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily UNIONOIDEA Rafinesque, 1820
Family UNIONIDAE s.s
Subfamily PARREYSIINAE Henderson, 1935
Tribe INDOCHINELLINI Bolotov, Pfeiffer, Vikhrev, & Konopleva, 2018

Genus Indonaia Prashad, 1918

Species Indonaia caerulea (Lea, 1831)

To find out more about Indonaia and southern Asian freshwater mussels, check out:
  • Bolotov, I.N., I.V. Vikhrev, A.V. Kondakov, E.S. Konopleva, M.Y. Gofarov et al. 2017. New taxa of freshwater mussels (Unionidae) from a species-rich but overlooked evolutionary hotspot in Southeast Asia. Scientific Reports 7 (11573): 1-18.
  • 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.
  • Konopleva, E.S., J.M. Pfeiffer, I.V. Vikhrev, A.V. Kondakov, M.Yu. Gofarov et al. 2019. A new genus and two new species of freshwater mussels (Unionidae) from western Indochina. Scientific Reports 9 (4106): 1-14.
  • Nesemann, H., S. Sharma, G. Sharma, S.N. Khanal, D.N. Shah et al. 2007. Aquatic Invertebrates of the Ganga River System (Mollusca, Annelida, Crustacea (in part)) 1. Published by Author, Taurus, Germany. 263 pp.
  • Ramakrishna & A. Dey. 2007. Handbook on Indian Freshwater Molluscs. Zoological Survey of India, Calcutta. 399 pp.
  • Simpson, C.T. 1900. Synopsis of the naiades, or pearly fresh-water mussels. Proceedings of the United States National Museum 22: 501-1044.
  • Subba Rao, N.V. 1989. Handbook Freshwater Molluscs of India. Zoological Survey of India, Calcutta. 289 pp.
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