Reappraising the species validity of Cuneopsis szechenyii comb. nov. (Neumayr, 1899) and revising the taxonomy of Middendorffinaia mongolica (Middendorff, 1851)

Kaiyu Hou; Liping Zhang; Lili Liu; Xiongjun Liu; Junli Jia; Ruiwen Wu

Just Accepted

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Reappraising the species validity of Cuneopsis szechenyii comb. nov. (Neumayr, 1899) and revising the taxonomy of Middendorffinaia mongolica (Middendorff, 1851)

Kaiyu Hou, Liping Zhang, Lili Liu , Xiongjun Liu, Junli Jia, Ruiwen Wu

Abstract

Freshwater bivalves (Bivalvia, Unionida, Unionidae) are one of the most threatened groups of animals in the world. Taxonomic uncertainties pose a particular challenge due to significant intraspecific variation and apparent plasticity in shell morphology among these species, which impedes efficient conservation planning and management. The species Unio szechenyii, which is endemic to China, has long been regarded as a synonym for Cuneopsis heudei due to the high convergence in shell morphology. The recently validated species Middendorffinaia mongolica is currently restricted to the Amur Basin and Primorye in eastern Russia. It is classified under the tribe Middendorffinaiini of the subfamily Unioninae within family Unionidae based on multilocus phylogeny. However, the lack of comprehensive taxonomic information and sufficient molecular phylogenetic data casts uncertainty on the validity and taxonomic status of these two species. The present study aims to reassess the validity of Unio szechenyii by integrating taxonomy, while confirm the taxonomic status of Middendorffinaia mongolica, which is new record for China, through robust mitochondrial phylogenomics. By integrating shell morphometry, soft-body anatomy, and molecular evidence, we support the validity of Unio szechenyii, and propose a recombination as Cuneopsis szechenyii comb. nov. By first determining the mitochondrial genome of Cuneopsis szechenyii, Cuneopsis kiangsiensis, Middendorffinaia mongolica, and Pseudocuneopsis wuana, we elucidate intrageneric relationships within the genera Cuneopsis and Pseudocuneopsis. Meanwhile, based on the updated consensus taxonomic framework including tribes and subtribes in Unioninae, mitochondrial phylogenomics strongly support the transfer of Middendorffinaia mongolica from the tribe Middendorffinaiini to the tribe Unionini and classify it under the subtribe Middendorffinaiina stat. rev.

IS24071 Accepted 16 November 2024