Multilocus and mitogenomic phylogenetic analyses reveal a new genus and species of freshwater mussel (Bivalvia: Unionidae) from Guangxi, China

Abstract

Freshwater mussels are essential for the integrity of freshwater ecosystems but numbers of these organisms are declining rapidly at regional and global scales. The phylogenetic and biogeographic aspects of the rich unionoid fauna of the Indo-Burma region are becoming increasingly well understood. Guangxi is part of the Chinese portion of the Indo-Burma biodiversity hotspot but regional studies of the freshwater mussel diversity are scarce. In this study, we report a new genus and species of freshwater mussel from Guangxi, China. Genetic datasets including three genes (COI, 16S rRNA and 28S rRNA) and complete maternal mitogenomes were compiled to infer the phylogenetic history of the group. Molecular phylogenetic analyses showed that the new species formed a monophyletic group and was closely related to Obovalis and Ptychorhynchus in the tribe Gonideini of the subfamily Gonideinae. Morphological and molecular evidence supported that these specimens represent an undescribed genus and species that we describe as Postolata guangxiensis gen. nov., sp. nov. The discovery of this new taxon adds to the known level of endemism of freshwater mussels in Guangxi and a detailed survey of uncharted areas should reveal new diversity in the future. We also suggest that complete mitogenomes or even genome-scale nuclear data should be used for phylogenetic reconstructions when proposing major taxonomic changes. ZooBank: urn:lsid:zoobank.org:pub:76FC5A1D-7507-4F26-A12C-EC08AB333274

Revisiting the genus Pseudocuneopsis (Bivalvia, Unionidae): Morphology, mitochondrial phylogenomics, and the description of a new species

“…These regions have the potential to harbour undiscovered, mysterious species. Recent studies conducted in China have revealed new species, thus corroborating this point (Chen et al, 2023;Dai et al, 2023;Wu, Liu, et al, 2021;Wu et al, 2022Wu et al, , 2023.…”

“…This is in agreement with our present phylogenetic results. It is crucial to use genome‐scale data (including the maternal mitochondrial genome) to reconstruct and verify the deep phylogenetic relationships of freshwater mussels when proposing new taxonomic groups (Dai et al., 2023).…”

“…In addition, pollution and urban development are significant contributors to habitat loss (Liu et al, 2023). Recent studies have shown that this habitat in China harbours some undiscovered species, such as the enigmatic species Diaurora aurorea (Heude, 1883), as well as newly discovered species D. laevis , and Postolata guangxiensis Dai, Huang, Guo & Wu, 2023(Chen et al, 2023Dai et al, 2023). Therefore, in addition to protecting known threatened species, governments and international organizations should prioritize the study and conservation of these overlooked small streams, as they harbour numerous local endemic taxa.…”

“…Such high species diversity and wide distribution make China one of the main hotspots for freshwater mussel research worldwide (Zieritz et al., 2018). However, current research has revealed a significant geographical bias concerning studies on freshwater mussels in China (Dai et al., 2023; Liu et al., 2022; Wu et al., 2022). Apart from the extensively studied middle and lower reaches of the Yangtze River, the biodiversity in other regions of China, especially in unexplored small streams, has been significantly undervalued (Dai et al., 2023; Wu et al., 2022).…”

“…However, current research has revealed a significant geographical bias concerning studies on freshwater mussels in China (Dai et al., 2023; Liu et al., 2022; Wu et al., 2022). Apart from the extensively studied middle and lower reaches of the Yangtze River, the biodiversity in other regions of China, especially in unexplored small streams, has been significantly undervalued (Dai et al., 2023; Wu et al., 2022). These regions have the potential to harbour undiscovered, mysterious species.…”