Two harpacticoid copepods, Pseudonsiella longicaudata. n. sp. and Xylora longiantennulata n. sp. belonging to the subfamily Donsiellinae are described. They were found in the wood infested by isopod of the genus Limnoria from the East Sea (Sea of Japan), Korea. The former species is characteristic in having the long caudal ramus and four setae on mandi bular basis. The latter one closely resembles X, nertica Hicks in general body form, but is clearly distinguished from X. nertica in that the antennule is much longer and the caudal ramus is longer, and leg 5 endopod bears four setae.