Mussel of the Month

Khairuloconcha sahanae is a new genus and species of freshwater mussels split from Ctenodesma borneensis* from Borneo based on recent molecular phylogenetic research (Zieritz et al., 2021). One of the specimens we photographed from the Field Museum of Natural History in 2003 was selected as a paratype, so we are prepared to present an image of this species for a Mussel of the Month post. That specimen record has been georeferenced and is the basis for the map we present on the Valid Species page.

Back when we started photographing specimens and serving the images on the Internet, it was a novel idea. The kind of virtual museum of freshwater bivalves that we have built still is pretty nifty, even with lots of collections now serving images of their specimens. But nowadays, the bases for new species are molecular rather than strictly morphological. Whether or not the hard or soft anatomy of a specimen has been observed, a phylogenetic analysis of a sequenced accessioned on Genbank can be sufficient to determine that a sample isn’t what it was originally identified to be. For example, the type specimens of Nyeinchanconcha nyeinchani were originally identified as Pseudodon cumingii (Pfeiffer & Graf, 2015; Lopes-Lima et al., 2017), but subsequent phylogenetic analysis resulted in a branch distinct from putative congeners (Bolotov et al., 2020). New genus, new species, no more polyphyly!

The same thing has happened with Khairuloconcha and Ctenodesma — although the former is still sister to Ctenodesma but separated by a long branch. Specimens that had been identified as C. borneensis from eastern Borneo (Zieritz et al., 2020) are now called K. lunbawangorum,** and C. borneensis is hypothesized to be restricted to the western part of the island (Zieritz et al., 2021).

To facilitate the use of DNA sequences accessioned on Genbank for phylogenetic work and species revision, we have been building a database of Genbank voucher specimens. You can see what we have going on so far if you scroll down below the specimen images on the MUSSEL Project Database Valid Species pages for Khairuloconcha sahanae, Ctenodesma borneensis, Nyeinchanconcha nyeinchani, or lots of other species. Where we have georeferenced Genbank vouchers, those localities are listed and marked on the specimen map. For each voucher (georeferenced or not), there is a single link to Genbank sequences associated with that single specimen. This is a growing dataset, so keep an eye on the MUSSELpdb for updates in the coming months.

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* Ctenodesma scheibeneri was Mussel of the Month back in June 2011. Back then we chose to highlight that species (which is only known from the type specimen and only mentioned by people making lists of freshwater mussels) because none of the images we had for C. borneensis (the type species of the genus) were as good as the one for C. scheibeneri.

** We didn’t make Khairuloconcha lunbawangorum, the type species, Mussel of the Month because we don’t have a picture of it. We do have one for K. sahanae (see above).