Hiroyuki Ariyama

Five species of the family Cyproideidae (Crustacea: Amphipoda) from Japan, with the description of a new genus and two new species

Five species of the family Cyproideidae (Crustacea: Amphipoda) are described from shallow sea in Japan. Cyproidea liodactyla Hirayama, 1978 was collected from Kanagawa and Shizuoka Prefectures and Ariake Sea. Morphological character of the antenna 1 in these specimens is different from the original description. Examining the paratypes of C. liodactyla, the shape of the antenna 1 in the holotype is revealed to be abnormal. Cyproidea okinawensis sp. nov. was collected from Okinawa Island. Its morphological characters resemble C. liodactyla and C. robusta Ren, 2006; however, this new species is different from the former in the smaller eyes, the narrower coxa 5 and the coloration, and from the latter in the ovoid telson. Metacyproidea gen. nov. is established with M. makie sp. nov. from Hachijo Island in Tokyo Prefecture as its type species. This new genus 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. Moolapheonoides acutifalcatus Kobayashi & Ishimaru, 2005 and Terepeltopes dolichorhunia Hirayama, 1983 were also collected from Wakayama and Fukui Prefectures and Kanagawa, Shizuoka and Yamaguchi Prefectures, respectively. A key to species of the family Cyproideidae in Japan is provided.

Three new species of the Eriopisa group (Crustacea: Amphipoda: Eriopisidae) from Japan, with the description of a new genus

Three new species of the Eriopisa group (Crustacea: Amphipoda: Eriopisidae) are described from coastal areas in Japan. Paraflagitopisa gen. nov. is established with P. excavata sp. nov. as its type species. This new genus is characterized by (1) entire lateral cephalic lobe, (2) unfused flagellum of antenna 2, (3) 3-articulated mandibular palp, (4) carpus of gnathopod 1 longer than propodus, (5) transverse palm of gnathopod 1, and (6) slender outer ramus of uropod 3 with long second article, and can be distinguished from the closely related genus, Flagitopisa, by the article 2 of mandibular palp longer than article 3, the undilated bases of pereopods 3-4, and the slender inner ramus of uropod 3. Psammogammarus lobatus sp. nov. is characterized by (1) male gnathopod 2 with excavated palm, (2) posterodistally projected bases of pereopods 5-7, (3) quadrate posteroventral corner of pleonal epimeron 3, (4) short inner ramus of uropod 3, and (5) article 2 of uropod 3 outer ramus longer than article 1. Victoriopisa wadai sp. nov. has the following characters: (1) eyes absent, (2) peduncle of antenna 1 not heavily setose, (3) accessory flagellum with 1-2 articles, (4) flagellum of antenna 2 composed of 2 long and 3 short articles, (5) gnathopod 2 in both sexes with excavated palm, (6) merus of pereopod 7 moderately expanded, and (7) ventral margin of pleonite 2 slightly setose. Key to species of the Eriopisa group in Japan is provided.

Species of the Maera-clade collected from Japan. Part 1: genera Maeropsis Chevreux, 1919 and Orientomaera gen. nov. (Crustacea: Amphipoda: Maeridae)

The Maera-clade is a group of maerid amphipod genera which has neither a falcate mandibular palp nor medially setose inner plates of maxillae 1 and 2. Two species of Maeropsis Chevreux, 1919 and four species of Orientomaera gen. nov. included in the clade, are described from Japan. Maeropsis okinawensis sp. nov. is described, based on collections from Okinawa Prefecture. It resembles M. cobia Krapp-Schickel, 2009, M. paphavasitae Wongkamhaeng, Coleman Pholpunthin, 2013, and M. serratipalma (Nagata, 1965). This new species differs from the latter three species in the long uropod 3. Maeropsis serratipalma is redescribed and newly recorded from Kanagawa, Osaka and Wakayama Prefectures. The new genus, Orientomaera, is described and is characterized by the mandibular palp article 1 without a distal tooth and the oblique palm of the gnathopod 2 with many robust setae. Orientomaera comprises four species: O. brevispina (Kim Kim, 1991) comb. nov. from Iwate, Fukui, Kyoto and Wakayama Prefectures and Ariake Sea; O. decipiens sp. nov. from Osaka and Wakayama Prefectures; O. obliquua sp. nov. from Osaka and Wakayama Prefectures; O. rotundicoxa sp. nov. from Kanagawa and Wakayama Prefectures. These species can be distinguished from one another by the coxa 1, the gnathopod 2 propodus, the pereopod 6 basis and the telson. Keys to species of Maeropsis and Orientomaera in the world are provided.

Two new species of eyeless amphipods from a coastal area in Japan (Crustacea: Amphipoda: Hadziidae, Melitidae), with reinstatement of the genus Paraniphargus Tattersall, 1925

ABSTRACT Two new species of eyeless amphipods are described from coastal Japan. Dulzura projecta sp. nov. (Hadziidae) was collected under large stones and in coarse sand from Osaka to Mie Prefectures. Dulzura projecta can be distinguished from the other Dulzura species by the distinct projection on article 1 of the male pleopod 3 inner ramus and the very long carpus of male gnathopod 1. Paraniphargus shiosai sp. nov. (Melitidae) was collected in coarse sand from Mie Prefecture, and can be differentiated from the other two species in the genus by the dorsal teeth on the pleonites, the smaller coxa 4 with shallow excavation and the shorter antenna 1 flagellum. Paraniphargus is reinstated as a distinct genus, following observation of the gnathopods, which revealed sexual monomorphism between males and females.

First record of Ericthonius megalopus (Sars, 1879) from bathyal Sagami Bay, central Japan, including synonymization of Ericthonius tolli Brüggen, 1909 with Ericthonius megalopus (Crustacea: Amphipoda: Ischyroceridae)

A couple of ischyrocerid amphipods included in the genus Ericthonius were collected from bathyal Sagami Bay (1456 m), central Japan. Morphological characters of the specimens closely resemble those of Ericthonius megalopus (Sars, 1879) and Ericthonius tolli Brüggen, 1909. Examining males and females of E. megalopus and E. tolli deposited in the Natural History Museum of Denmark, the specimens of both the species were quite similar to the Japanese specimens, although the shapes of appendages vary with growth and locality; therefore, E. tolli is synonymized with E. megalopus and all the specimens are identified as E. megalopus. Ericthonius megalopus is distributed in the northern sea areas of the world at a wide range of depths, and the present occurrence from Japan is the southernmost and deepest record of the species.