Integrative taxonomy reveals a new cryptic species of Raphidopus Stimpson, 1858 (Decapoda, Anomura, Porcellanidae) from the Yellow Sea and East China Sea

Raphidopus ciliatus Stimpson, 1858 is believed to be widely distributed across the Indo-West Pacific and has been reported along the entire coast of China. However, molecular and morphological analyses reveal the presence of a cryptic species in northern Chinese waters, described herein as R. xinzhengi Dong, Wan & Wang sp. nov. The COI sequences of the two species of Raphidopus show 8.7–9.0% divergence, higher than each intraspecific variation. The new species can be distinguished from R. ciliatus primarily by the arrangement of granules on the cheliped carpus, the length/width ratio of the cheliped carpus, and the length/width ratio of the merus of the first ambulatory leg. An updated key to the species of the genus Raphidopus is provided.