Mitogenome phylogeny reveals Indochina Peninsula origin and spatiotemporal diversification of freshwater crabs (Potamidae: Potamiscinae) in China

Abstract

The Asian potamid subfamily Potamiscinae is the most species-rich group of primary freshwater crabs in the world, and a large number of these (318 species in 52 genera) are found in China where they exhibit a remarkably high rate of endemism. However, the evolutionary history and phylogenetic relationships of this subfamily is still poorly understood and the hypothesis that the Chinese potamids originated in the Indochina Peninsula has yet to be tested using a modern phylogeographic reconstruction and molecular dating methods. Here we analyze the phylogenetic relationships and biogeographic history of the Chinese potamiscines based on whole mitogenomes of 72 species of Asian freshwater crabs representing 65% of the potamiscine genera found in China, including new mitogenome sequences for 57 species. The mitogenomic phylogeny generated four separate clades: Southwest China (SWC), Indochina-Southwest China (ISWC), Central China (CC), and South China-adjacent Islands (SCI). Our results suggest that the Chinese potamiscine fauna most likely originated in Indochina during the Eocene. The establishment of the East Asian monsoon during the Eocene/Oligocene resulted in major climate changes that coincide with the local diversification of the CC and SCI clades. In addition, diversification of two other clades (ISWC and SWC) may have been driven by past large scale environmental changes taking place at that time such as increased local precipitation and expanding freshwater habitats associated with the uplifting of the Hengduan Mountains. In addition, our phylogenies did not support monophyly for six currently recognized potamiscine genera, highlighting the need for further taxonomic revisions of this fauna. The broad taxonomic sampling and well-supported molecular phylogenies used here allow for the updating of our understanding of the evolutionary origins and diversification of the potamiscine freshwater crabs in China.

Mitochondrial genomic characterization of two endemic Chinese freshwater crabs of the genus Sinopotamon (Brachyura: Potamidae) and implications for biogeography analysis of Potamidae

“…Among them, S. chishuiense and S. yaanense formed one clade while S. wushanense , S. kenliense , and S. exiguum clustered one clade (Figure 5). The nonmonophyly of the Sinopotamon crabs had been widely reported (Ji, 2016) and the Sinopotamon maintained a closer relationship with the Vadosapotamon , Latopotamon , and Tenuilapotamon (Pan et al, 2022; Zhang et al, 2020), which was also consistent with Sinopotamon being most closely related to Tenuilapotamon in our study.…”

“…The extrusion of the Cenozoic Indian and Pacific plates onto the Asian and European continents and the associated orogeny led to the uplift of numerous mountain ranges of different elevations and spans within China (Deng et al, 2016; Guo, 1994; Sanzhong et al, 2019; Zhang, 1993). Therefore, the weak dispersal capacity and the geographic isolation factors such as mountain systems and water systems may have led to the evolution of Sinopotamon species diversity in the China, and that may also be an important reason for its nonmonophyletic nature (Chen et al, 2012; Pan et al, 2022; Zhang et al, 2020).…”

Revision of two species of Sinopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) endemic to China: a new combination and a new synonym

“…9 ). The phylogenetic relationship showed that the genus Huananpotamon is monophyletic and belongs to the “South China-adjacent Islands” clade ( Pan et al 2022 ) (Fig. 9 ).…”

“…A total of 43 sequences from the ingroup and outgroup taxa were used in the phylogenetic analyses, including 33 downloaded sequences (Table 1 ). Pan et al (2022) showed that the genus Huananpotamon nested within the “South China-adjacent Islands” clade; therefore, closely related genera from the same clade, in particular the taxa of closely related genera from Fujian, Guangdong, and Jiangxi, and some others from adjacent islands, were included for the present phylogenetic analyses (Table 1 ). For the genus Huananpotamon , eight species from the adjacent area of the Wuyishan National Park were included, of which four species are morphologically most similar to H. koatenense (Table 1 ; Fig.…”

“…9 ). Ten species belonging to the closely related “Central China” and “Indochina-Southwest China” clades ( Pan et al 2022 ) were used as outgroups. Among them, two specimens of S. fukienense , collected from Guadun (Koaten) and Shaowu of Fujian Province were also included in our phylogenetic analyses (Table 1 ).…”