Three rare sentinel crab species (Crustacea: Decapoda: Brachyura: Macrophthalmidae) from the Ryukyu Archipelago, including newly-recorded species from Japan

琉球列島で採集された標本に基づき, オサガニ類の3 稀種, オオカクオサガニ ( 新称)Macrophthalmus (Mareotis) purpureocheir Teng& Shih, 2015, ヒメノコハオサガニM. (Venitus)barnesi Serène, 1971, ノコハオサガニM. (V.)latreillei (Desmarest, 1822) を報告した. このうち,オオカクオサガニは日本初記録である. 本稿ではこれら3 種の形態や色彩, 生息環境について記述した.Three rare sentinel crabs, Macrophthalmus (Mareotis) purpureocheir Teng & Shih, 2015, M. (Venitus) barnesi Serène, 1971, and M. (V.) latreillei (Desmarest, 1822) are collected from the Ryukyu Archipelago. Macrophthalmus purpureocheir is newly added to the Japanese fauna. Notes on their morphological features, colorations, and ecological aspects are provided