Two new species of potamid crabs, Eosamon daiaesp. nov. and Indochinamon malipoensesp. nov. are described from the Sino-Burmese border, southwestern Yunnan and from the Sino-Vietnamese border, southeastern Yunnan, China. The two new species can be distinguished from their closest congeners by several characters, among which is the form of the first gonopod structures. Molecular analyses based on partial mitochondrial 16S rDNA sequences also support the systematic status of these new taxa.

Aims:The biodiversity of tropical islands is a popular topic in global biodiversity conservation research. Hainan Island is the largest tropical island in China. Freshwater crabs are a keystone species for freshwater ecosystems in Hainan Island. The aims of this study were thus to identify the distribution pattern and assess the threat status of freshwater crabs in Hainan Island. Methods: In this study, we used field surveys and conducted a literature review to investigate the species diversity and conservation status for freshwater crabs in Hainan. Results: Our results indicate that the diversity hotspots for freshwater crab species on Hainan Island are located in the south-central mountainous area (especially Bawangling, Yinggeling, Mihouling, Wuzhi Mountain, Diaoluo Mountain and Jianfengling). Freshwater crab diversity is higher in the central and southern mountains and lower in the plains. According to the IUCN Red List Categories and Criteria, 16.7% of freshwater crab species on Hainan Island are

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Environmental DNA (eDNA) refers to DNA fragments that organisms leave behind in their surrounding environment (such as soil, sediment and water). eDNA technology sequences these DNA fragments and can provide information on taxonomic composition of benthic macroinvertebrate communities. Compared with traditional biological survey methods, eDNA technology is more sensitive, efficient and noninvasive. As a novel method for surveying aquatic organisms, eDNA techniques have been widely used in biodiversity assessments of aquatic organisms, including monitoring of endangered, rare and invasive species. In this review, we summarize recent developments in eDNA technology and focus primarily on the operational procedure and its application for freshwater benthic macroinvertebrate analyses. Finally, we discuss the advantages and potential caveats of current eDNA practices.