Metadulichia kohtsukai, Ariyama, 2019

Ariyama, Hiroyuki, 2019, Four Species of Dulichiidae (Crustacea: Amphipoda) from Japan, with the Description of a New Genus and Two New Species, Species Diversity 24 (1), pp. 29-48 : 44-47

publication ID	https://doi.org/ 10.12782/specdiv.24.29
publication LSID	lsid:zoobank.org:pub:7287B998-E838-400C-94C7-B66C21FF35FE
DOI	https://doi.org/10.5281/zenodo.4734572
persistent identifier	https://treatment.plazi.org/id/D974A44F-B2E8-4F73-BD75-C3FA3B9979F6
taxon LSID	lsid:zoobank.org:act:D974A44F-B2E8-4F73-BD75-C3FA3B9979F6
treatment provided by	Felipe
scientific name	Metadulichia kohtsukai
status	sp. nov.

Treatment

Metadulichia kohtsukai View in CoL sp. nov.

( Figs 14–16 View Fig View Fig View Fig )

[Japanese name: Hosonaga-shakutoridoronomi, new]

Material examined. Holotype: male (OMNH-Ar-10824), 3.5mm, Sagami Bay, southwest of Miura City , Kanagawa Prefecture, 35°06′57"N, 139°33′44"E– 35°06′43"N, 139°34′03"E ( Fig. 1E View Fig ), 230–398 m depth, using dredge, 10 December 2015, coll. H. Kohtsuka. GoogleMaps

Diagnosis. Eyes ovate. Accessory flagellum 3-articulate. Maxilla 1 small, outer plate bearing 7 terminal robust setae, palp with 3 robust setae at tip. Maxilla 2 inner plate with single mediofacial seta. Male gnathopod 2, basis short, propodus massive, subovoid, posterior margin weakly setose, with small proximal and distal projections and small swelling. Pereopods 3, 4 bases slender. Pereopod 5 elongate, not prehensile. Urosomite 1 about 1.65 times as long as pleonites 2+3. Uropod 2 outer ramus very short, 17% as long as inner ramus.

Description of male [based on holotype (OMNH-Ar-10824), 3.5 mm]. Body ( Fig. 14 View Fig ) smooth, dorsal margins with sparse short setae, urosomite 1 about 1.65 times as long as pleonites 2+3. Eyes ovate, about 35% length of head, composed of many tight ommatidia.

Antenna 1 ( Fig. 15A, A View Fig 1 View Fig ) slender, about same length as body, posterior margin setose; length ratio of peduncular articles 1–3 1.0: 2.3: 2.8; accessory flagellum short, 3-articulate; primary flagellum with 6 articles, tip minute. Antenna 2 ( Fig. 15B View Fig ) slender, about 0.7 times as long as antenna 1, posterior margin setose; length ratio of peduncular articles 3–5 1.0: 7.5: 6.3; flagellum with 3 articles. Upper lip ( Fig. 15C View Fig ), ventral margin bare. Mandibles ( Fig. 15D, D View Fig 1, E, E1 View Fig ) with length ratio of palp articles 1–3 1.0: 3.6: 2.0, articles 2, 3 bearing 5 and 3 setae, respectively; incisor with 4 cusps, lacinia mobilis with 3 cusps, 4 accessory blades present in both sides; molar with spatula-like process in right. Lower lip ( Fig. 15F View Fig ), outer plates with sparse setae apically. Maxilla 1 ( Fig. 15G, G View Fig 1 View Fig ), outer plate with 7 robust setae distally, palp article 2 bearing 3 robust and 1 slender setae distally and 3 slender setae laterally. Maxilla 2 ( Fig. 15H View Fig ), inner plate with distal setae, very thin lateral setae and single mediofacial seta; outer plate bearing many setae on distal margin. Maxilliped ( Fig. 15I View Fig ), inner plate with 3 apical and 1 mediodistal short robust setae on ventral surface; outer plate bearing 5 robust setae mediodistally.

Gnathopod 1 ( Fig. 16A View Fig ) relatively slender; coxa with ventral notch; merus setose posterodistally and mediodistally; carpus longer than basis, with many setae on posterior margin; propodus slender, with many setae posteriorly, mediodistal surface heavily setose; dactylus long, slender, curved posteriorly. Gnathopod 2 ( Fig. 16B, B View Fig 1 View Fig ), coxa subrectangular, ventral margin straight, gill small; basis short, anterodistal corner lobate; carpus setose posteriorly; propodus massive, subovoid, about 0.9 times as long as head, about 1.7 times length of carpus, posterior margin weakly setose, with short proximal projection at about 70° angle to palm, small distal projection at about 50° angle to palm and small swelling on distal side of proximal projection; dactylus curved posteriorly, posterior margin roundly produced proximally.

Pereopods 3, 4 ( Fig. 16C, C View Fig 1 View Fig , D) slender, pereopod 3 slightly longer than pereopod 4; coxae triangular, gills long; bases elongate, about 5.2 and 4.8 times as long as width respectively, each with glands in anterodistal and posteroproximal parts; propodi and dactyli narrow. Pereopod 5 ( Figs 14 View Fig , 16E, E View Fig 1 View Fig ) long; coxa triangular, gill small; basis–carpus with many short robust setae, carpus about 0.55 times as long as propodus; propodus lacking palm, anterior margin bearing 3 robust setae; dactylus long. Pereopods 6, 7 ( Fig. 14 View Fig ) lost except for coxae.

Pleopods ( Fig. 16 View Fig F–H), peduncles progressively longer, each with 2 slender coupling hooks; outer rami slightly longer than inner rami, outer rami with 7, 7, 6 articles respectively, inner rami each with 6 articles. Uropod 1 ( Fig. 16I View Fig ), peduncle with 3 lateral and 2 medial robust setae; outer ramus about 0.85 times as long as inner ramus (including distal robust setae), with 2 lateral, 1 medial and 2 distal (long and short) robust setae; inner ramus bearing 2 lateral, 4–5 medial and 2 distal (long and short) robust setae. Uropod 2 ( Fig. 16D View Fig ) about half length of uropod 1 (including distal robust setae); peduncle with 2 medial robust setae; outer ramus very short, 17% as long as inner ramus, without setae; inner ramus bearing 1–2 lateral and 2 medial robust setae. Telson ( Fig. 16D View Fig ) bare.

Female. Unknown.

Coloration in life. Unknown.

Etymology. Dedicated to Hisanori Kohtsuka of the University of Tokyo for donating many amphipod specimens and their photographs.

Habitat. Bottom sediment unknown, 230–398 m depth.

Distribution. Japan: Sagami Bay (present study).