Metadulichia, 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

Metadulichia gen. nov.

[Japanese name: Hosonaga-shakutoridoronomi-zoku, new]

Type species. Metadulichia kohtsukai sp. nov., by original designation.

Diagnosis. Body cylindrical, but urosomites depressed dorsoventrally; pereonites 6, 7 fused; urosomites flexed beneath posterior pereonites and pleonites 1–3, urosomite 1 elongate, much longer than pleonites 2+3, urosomites 2, 3 coalesced, shorter than urosomite 1. Head triangular, rostrum small. Antennae long, slender; antenna 1 peduncular article 3 longest, accessory flagellum 3-articulate; antenna 2 shorter than antenna 1. Upper lip broad, fleshy, ventral margin bilobed. Mandible, molar large; palp with 3 articles, article 2 longest, article 3 rectolinear. Lower lip with welldeveloped inner lobes, outer lobes each with short mandibular lobe. Maxilla 1 small; inner plate rudimentary, without setae; outer plate bearing 7 terminal robust setae; palp 2-articulate, with 3 robust setae at tip. Maxilla 2 inner plate with single mediofacial seta. Maxilliped inner plate with several short robust setae; outer plate not reaching apex of palp article 2; palp consisting of 4 articles, article 4 with stout seta. Coxae small, short, discontiguous; gills present on coxae 2–5; oostegites of female unknown. Gnathopod 1 weakly subchelate, rather simple; carpus longer than propodus, carpus–dactylus long. Male gnathopod 2 larger than gnathopod 1, subchelate; carpus much shorter than propodus, propodus wide, posterior margin with proximal and distal projections, palm oblique, dactylus long. Female gnathopod 2 unknown. Pereopods 3, 4 short, subsimilar to each other; basis slender, glandular. Pereopod 5 long; basis and merus linear, propodus without palm. Pereopods 6, 7 unknown. Pleopods large, each with developed peduncle. Uropod 1 slender, biramous, peduncle shorter than both rami, outer ramus shorter than inner ramus; uropod 2 shorter than uropod 1, peduncle shorter than inner ramus, outer ramus extremely shorter than inner ramus; uropod 3 absent. Telson entire, ovate, longer than broad.

Etymology. From the Greek meta (=beyond) and Dulichia (related genus).

Gender. Feminine.

Included species. Metadulichia kohtsukai sp. nov.

Remarks. This new genus is characterized by the small maxilla 1 with 7 terminal robust setae on the outer plate and with 3 robust setae at the tip of palp, the maxilla 2 inner plate bearing single mediofacial seta, and the uropod 2 outer ramus extremely shorter than the inner ramus. These features are unique in the family Dulichiidae .