Genus Metacyproidea, new [Japanese name: Kawari-hoteiyokoebi-zoku, new] Type species. Metacyproidea makie sp. nov. by monotypy. Diagnosis. Most of morphological characters share with Cyproidea. Different characters from Cyproidea are as follows. Urosomites not keeled, urosomites 2–3 coalesced, posterodorsal end of coalesced urosomites strongly projected. Antenna 1 stout, peduncular article 2 dorsally crested, distal end distinctly toothed; accessory flagellum vestigial; flagellum short, with 10–16 articles. Upper lip incised, asymmetrical, with large roundish appendix. Mandible, incisor and accessory blades developed, molar reduced; palp slender, with 3 articles. Lower lip, inner lobes present. Maxilla 1, inner plate medium-sized; outer plate with 7 distal robust setae; palp 1-articulated, with 6 robust setae apically, mediodistal margin serrated. Coxa 6 wide. Telson reaching three fourths of uropod 3 peduncle, distal end truncate. Etymology. From the Greek meta (= beyond) and Cyproidea (related genus). Remarks. Metacyproidea gen. nov. closely resembles Cyproidea, especially in the peduncular article 2 of antenna 1 with a distinct distal tooth and the posterodorsal end of urosomites with a strong projection. However, Metacyproidea can be distinguished from Cyproidea by the coalesced urosomites 2–3 and the antenna 1 with a 10– 16-articulated flagellum. Detail structure of the mouth parts and width of the coxa 6 are also different. In addition, Paracyproidea Stebbing, 1899 has such a tooth of the antenna 1 (Moore 1992), but its telson is fleshy (Cyproidea and Metacyproidea have a flattened telson). Included taxa. Metacyproidea makie sp. nov.

Published as part of Ariyama, Hiroyuki, 2016, Five species of the family Cyproideidae (Crustacea: Amphipoda) from Japan, with the description of a new genus and two new species, pp. 301-331 in Zootaxa 4097 (3) on page 314, DOI: 10.11646/zootaxa.4097.3.1, http://zenodo.org/record/263937