Inversidens rentianensis: A new species of Freshwater Mussel from Jiangxi Province, China.

The genus Inversidens was established in 1911 by the German zoologist Fritz Haas, to describe two species of Freshwater Mussels (Uniomoids) from Japan, Inversidens brandtii and Inversidens parcedentata. Haas revisited the genus in 1969 adding a further four species, Inversidens reinianus, Inversidens haconensis, and Inversidens japanensis, from Japan, and Inversidens pantoensis, from China. Howeverr, other mallacologists subsequently removed several of these, so that only two species Inversidens brandtii from Japam and the Chinese Inversidens pantoensis now remain.

In a paper published in the journal ZooKeys on 3 August 2021, Ruiwen Wu of the School of Life Science at Shanxi Normal University, Xiongjun Liu, of the School of Life Science at Jiaying University, Takaki Kondo of the Division of Natural Science at Osaka Kyoiku University, and Shan Ouyang and Xiaoping Wu of the School of Life Sciences at Nanchang University, describe a new species of Inversidens from Jiangxi Province in China.

The new species is named Inversidens rentianensis, where 'rentianensis' means 'from Rentian' , in reference to the town of Rentian, which is near where the species was discovered. The shell of the new species is subtriangular and inflated, with a rounded anterior margin, an almost straight ventral margin, and an obliquely arc-shaped posterior margin. The umbos (prominences above the hinge) are well developed, but slightly eroded. Only one tooth is present on each valve. The shell is covered by a shiny black or brownish yellow skin, the shell itself is a reddish-brown colour. The shells are 43–52 mm in length and 29–36 mm in height. The species is known only from the Mianshui River near Renrian.

 

Shell of Inversidens rentianensis. Wu et al. (2021).

Species of Freshwater Mussels can be difficult to tell apart, as they tend to be morphologically variable, responding to their local environment, and show a high degree of physical convergence with other species. To counter these problems, Wu et al. carried out a genetic analysis using the mitochondrial cytochrome oxidase subunit I gene sequence, which has been widely used to delimitate Freshwater Mussel species. This analysis recovered Inversidens rentianensis as the sister species to Inversidens brandtii, enabling them to be confident of its assignment to the genus Inversidens.

 

The section of the Mianshui River near Renrian in Jiangxi Province, China, where Inversidens rentianensis was discovered, and its only known location to date. Wu et al. (2021).

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