First records of two raninoid crabs, Lyreidus tridentatus De Haan, 1841 and Cosmonotus mclaughlinae Tavares, 2006 (Decapoda, Brachyura) from South Korean waters

Two raninoid crabs, Lyreidus tridentatus De Haan, 1841 and Cosmonotus mclaughlinae Tavares, 2006 from around Jeju Island and the Straits of Korea, are firstly reported from Korean waters. The raninoid crabs currently comprise 4 species in Korea. Brief descriptions and illustrations of selected parts are provided in this article as evidence supporting their correct identifications.