Description of a new species of brackish-water crab of the genus Ptychognathus Stimpson, 1858 (Crustacea: Brachyura: Varunidae) from southern Taiwan

Abstract

The brackish-water crabs of the genus Ptychognathus Stimpson, 1858, the most diverse genus in the family Varunidae, inhabit the estuaries or seashores influenced by freshwater. Ptychognathus sakaii, a new species from Kenting, southern Taiwan, is described in this study, with a comprehensive key to the ten species of this genus from Taiwan. This new species is similar to its congeners, but can be distinguished mainly by the features of the carapace, ambulatory legs, and male first gonopods.

Adaptive evolution characteristics of mitochondrial genomes in genus Aparapotamon (Brachyura, Potamidae) of freshwater crabs

“…Therefore, they have been widely used in various studies, such as those on genetic diversity [ 27 , 28 ], phylogenetic analysis [ 29 , 30 ] and biogeography [ 31 ]. The mitochondrial gene cytochrome oxidase subunit I ( COX1 ) has been commonly used as a molecular marker for phylogenetic analysis of freshwater crabs and is considered a DNA barcode [ 18 , 32 , 33 ]. Other nuclear genes, such as 28S rRNA, are also used as supplements to increase the credibility of the results [ 34 ].…”

“…Other nuclear genes, such as 28S rRNA, are also used as supplements to increase the credibility of the results [ 34 ]. Due to the limitations of studies based on single-gene molecular markers and the accessibility of the complete mitochondrial genome [ 35 ], comparative mitogenome analysis has widely been carried out in studies on species diversification [ 33 , 36 , 37 ]. In this study, five complete mitogenomes were sequenced, and the mitogenome sequences of all 13 species in the genus Aparapotamon were analysed, revealing the molecular mechanism of species diversification.…”