Eco-certified Ashtamudi short-neck clam acquires its rightful identity

Fishermen fishing Ashtamudi short-neck clam.

Even though the short-neck clam is the major resource and export coming from Ashtamudi Lake in Kerala, India – the first fishery to be awarded with a a Marine Stewardship Council certification for sustainability in the country, a recent study found out that the mollusc had been subject to mistaken identity.

Further, this is not the first time when the species and genus name of this clam has been changed. At first, the species was identified as Paphia malabarica, which is also the name one could read in all hitherto published reports, including the Marine Stewardship Council’s register. Later on, as the name was proved to not be compliant with the current nomenclature, the Ashtamudi short-neck clam began to be referred to as Protapes gallus.

 Marcia recens from Ashtamudi lake, India.

However, the latest in-depth taxonomic study points to the clam having been misidentified from the very beginning. According to the finding of the team of A. Arathi, R. Ravinesh and A. Biju Kumar of the Department of Aquatic Biology and Fisheries, University of Kerala, and Graham Oliver of National Museum Wales, United Kingdom, the Ashtamudi short-neck clam belongs to a totally different genus, while its rightful scientific name actually is Marcia recens. Their paper was published in the open access journal ZooKeys.

Protapes gallus (Paphia malabarica) (above) and Marcia recens (below) showing obvious external morphological variations.

During their research, the scientists identified another edible species from Ashtamudi Lake that belongs to the Marcia genus: Marcia opima. While it could easily be mistaken for its commercially important relative thanks to a multitude of colour variations, it does not appear to contribute significantly to the export. Meanwhile, the actual species identified as Paphia malabarica (Protapes gallus) can be found in shallow coastal waters in the south of the country, but not in the studied brackishwater lake.

“No deleterious effects on the viability of the fishery have resulted from this error in identification, but from a legislative perspective applying the incorrect name to the exploited species could undermine its certification and protection,” comment the researchers.
“On the basis of this study, the species involved in the Marine Stewardship Council certification would be better considered at the generic level of Marcia or at the species level for Marcia recens, the most dominant species in the Ashtamudi Lake clam fishery zone.”

In conclusion, the authors of the study say that, “misidentification can undermine comparative biological studies and conservation, while more molecular studies are required to resolve the taxonomy of all clams involved in fishery.”

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Original source:

Arathi AR, Oliver PG, Ravinesh R, Kumar AB (2018) The Ashtamudi Lake short-neck clam: re-assigned to the genus Marcia H. Adams & A. Adams, 1857 (Bivalvia, Veneridae). ZooKeys 799: 1-20. https://doi.org/10.3897/zookeys.799.25829

Photos by Dr Biju Kumar.

New species of pea-size crab parasitizing a date mussel has a name of a Roman god

Tiny crabs, the size of a pea, dwell inside the mantles of various bivalves, living off the food filtered by their hosts. A new species of these curious crustaceans has recently been reported from the Solomon Islands, where an individual was found to parasitise a large date mussel.

Because of the new pea crab’s characteristic large additional plate, covering its upper carapace, giving it the illusion of having two faces, it has been named after Janus, the Roman two-faced god. Discoverers Dr Peter Ng, National University of Singapore, and Dr Christopher Meyer, U.S. National Museum of Natural History, Smithsonian Institution, have their findings published in the open access journal ZooKeys.

Being only the second species in the genus (the first was from Malaysia), the new pea crab Serenotheres janus can be distinguished by its broader carapace and other features. It is cream-yellow in colour.oo_106009

Both representatives of the genus are unique in having an additional large plate covering the upper side of the carapace. However, its purpose is still unknown. The two pea crabs are also the only known parasites of the rock-boring bivalves of the mytilid subfamily Lithophaginae.

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Original source:

Ng PKL, Meyer C (2016) A new species of pea crab of the genus Serenotheres Ahyong & Ng, 2005 (Crustacea, Brachyura, Pinnotheridae) from the date mussel Leiosolenus Carpenter, 1857 (Mollusca, Bivalvia, Mytilidae, Lithophaginae) from the Solomon Islands. ZooKeys 623: 31-41. doi: 10.3897/zookeys.623.10272