A new species of the genus Nihonotrypaea Manning & Tamaki, 1998, Nihonotrypaeahainanensis sp. n., collected from the South China Sea, is described and illustrated. It is distinguishable from Nihonotrypaeaharmandi (Bouvier, 1901), Nihonotrypaeajaponica (Ortmann, 1891), Nihonotrypaeathermophila Lin, Komai & Chan, 2007 and Nihonotrypaeamakarovi Martin, 2013 by having the elongated carpus of the male and female major cheliped. The new species is distinguishable from Nihonotrypaeapetalura (Stimpson, 1860) by the proximolower margin of the carpus of the male major cheliped bearing several small denticles.
Keywords: Callianassidae; Nihonotrypaea; South China Sea; new species.