Abstract

Two species of Maera Leach, 1814, a species of Meximaera Barnard, 1969 and a species of Orientomaera Ariyama, 2018 included in the Maera clade, are described from Japan. Maera loveni (Bruzelius, 1859) was collected from the Sea of Japan and can be distinguished from its congeners by the very large body size and the gnathopod 2 palm defined by a blunt tooth bearing a strong robust seta. Maera sagamiensis sp. nov. from Sagami Bay is characterized by the presence of small notches on the coxae 1–3. Meximaera mooreana (Myers, 1989) was collected from Wakayama Prefecture and has two distinct characters: the male gnathopod 2 with wide basis and the very long uropod 3. Morphological characters of the Japanese specimens resemble well those in the literature, but the mandibular palp article 1 is projected acutely. Orientomaera incisa sp. nov. was recently collected from Wakayama Prefecture and its gnathopods 2 in both sexes bear a distinctive incision on the palm. Keys to species of Meximaera in the world and Japanese species of the Maera-clade are provided. Fifteen species included in the Maera-clade occur in Japan.