A new species of Geothelphusa Stimpson, 1857, from Taiwan (Crustacea : Brachyura : Potamidae) based on morphological and molecular evidence, with notes on species from western Taiwan

Abstract

A new species of freshwater crab of the genus Geothelphusa, G. siasiat sp. nov., is described from Hsinchu and Miaoli counties, northwestern Taiwan. The new species can be distinguished morphologically from similar and geographically close species from western Taiwan by a suite of characters of the carapace, ambulatory legs, thoracic sternum, male abdomen, and male first pleopods. Comparisons of the DNA sequences encoding parts of the mitochondrial large subunit (16S) rRNA and cytochrome oxidase subunit I (COI) genes of specimens from western Taiwan further corroborate this finding. The opportunity is taken here to discuss the taxonomy of the poorly known species, Geothelphusa candidiensis Bott, 1967, based on a re-examination of the holotype, and the distribution of Geothelphusa species from western Taiwan. The report of G. siasiat sp. nov. brings the total number of species of Geothelphusa species known to 52.