No abstract

Two new complete mitogenomes of the grapsids, Metaplax longipes Stimpson, 1858 and Nanosesarma minutum (De Man, 1887) were sequenced using next-generation sequencing (NGS). By analyzing a combination of 75 Brachyura taxa, our phylomitogenomic inferences suggested that Metaplax crab seperated earlier from the sesarmid crabs and closely related to the varunids with respect to Nanosesarma crab. It reconfirmed that the Metaplax should be removed from the Sesarmidae and assinged to the Varunidae. Additional mitogenomic comparisons including gene rearrangement and genomic organization were conducted among the 33 taxa of Grapsoidea and Ocypodoidea, and a shared rearrangement pattern between Metaplax longipes and the varunids were recovered, which also strongly supported the inference for the phylogenetic position of the Metaplax.

The complete mitogenome of the semiterrestrial crab Chiromantes neglectum was sequenced. It contained the entire set of 37 genes. The gene order was basically identical to pancrustacean ground pattern, except for the trnH and trnQ genes. Phylogenetic inferences based on protein-coding genes (PCGs) provide strong evidence that places C. neglectum within an intermingled ‘Grapsoidea & Ocypodoidea’ clade.

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.

These results suggest that this triple therapy promotes a local antitumor immune response with systemic consequences. The efficacy and limited toxicity of this strategy are attractive for clinical translation.