Exploring Freshwater Crab Diversity in Ban Tham Subdistrict, Phayao Province, Thailand Through Morphology and DNA Barcoding

Freshwater crabs are important biological resources in northern Thailand, yet their diversity remains poorly documented in many areas. This study investigated freshwater crab diversity in Ban Tham Subdistrict, Dok Khamtai District, Phayao Province, using morphological examination and mitochondrial cytochrome c oxidase subunit I (COI) DNA barcoding. A total of 69 specimens were assigned to four taxa. Indochinamon bhumibol and Sayamia bangkokensis were identified to species level, whereas two unidentified taxa were provisionally designated Potamidae sp. 1 and Potamidae sp. 2. Genetic diversity varied among taxa, with Potamidae sp. 2 showing the highest haplotype and nucleotide diversity, whereas S. bangkokensis showed no haplotype variation. Pairwise K2P distances revealed substantially greater divergence among taxa than within taxa. Phylogenetic analysis resolved the four taxa into distinct clades, while Automatic Barcode Gap Discovery (ABGD) recovered four molecular operational taxonomic units in the initial partition, corresponding to the four taxa. These results support the genetic distinctiveness of Potamidae sp. 1 and Potamidae sp. 2, although their species identities remain unresolved. Further taxonomic and molecular studies are required to clarify their identities. These findings provide baseline information for the conservation and sustainable management of freshwater crab resources in the study area.