Redescription of the brackish water crab Ptychognathus glaber Stimpson, 1858 based on the topotypic material from the Ogasawara Islands and new record of P. lipkei N.K. Ng, 2010 from Japan (Decapoda: Brachyura: Varunidae)

A critical re-evaluation of the brackish water crab Ptychognathus glaber reveals its geographic distribution is likely limited to the Ogasawara Islands, Japan, while specimens previously identified as P. glaber from the Ryukyu Islands belong to a distinct species, P. lipkei, newly recorded in Japan. This study provides a detailed redescription of P. glaber and compares it with P. lipkei using morphological and genetic analyses, including mitochondrial 16S rRNA gene sequences. The findings clarify taxonomic confusion and suggest that P. glaber is genetically closer to P. ishii, prompting further morphological comparisons between these species. This research corrects historical misidentifications and advances the understanding of crab biodiversity in Japanese waters.

KOMAI, T., MAENOSONO, T., SAEKI, T., & NARUSE, T. (2021). Redescription of the brackish water crab Ptychognathus glaber Stimpson, 1858 based on the topotypic material from the Ogasawara Islands and new record of P. lipkei N.K. Ng, 2010 from Japan (Decapoda: Brachyura: Varunidae). Zootaxa, 5048(1), 58–76. https://doi.org/10.11646/zootaxa.5048.1.3