Dulichia latimana, 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 : 32-40

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.4734564
persistent identifier	https://treatment.plazi.org/id/346BFD52-F90B-4CB4-9BD5-1143C585B512
taxon LSID	lsid:zoobank.org:act:346BFD52-F90B-4CB4-9BD5-1143C585B512
treatment provided by	Felipe
scientific name	Dulichia latimana
status	sp. nov.

Treatment

Dulichia latimana sp. nov.

( Figs 6–10 View Fig View Fig View Fig View Fig View Fig )

[Japanese name: Oki-shakutoridoronomi, new]

Material examined. Holotype: male (OMNH-Ar-10812), 5.1 mm, Ariake Sea, southeast of Minami-shimabara City , Nagasaki Prefecture, 32°39′01"N, 130°23′01"E (St. AG 16, Fig. 1I View Fig ), 50 m depth, sandy bottom, using Smith-McIntyre grab, 12 May 2006, coll. K. Mori. GoogleMaps Paratypes: male (OMNH-Ar-10813), 4.9 mm, same data as holotype; 3 males (OMNH-Ar-10814–10816), 5.9, 4.4 and 4.3 mm, and 2 ovigerous females (OMNH-Ar-10817, 10818), 5.4 and 4.7 mm, Ariake Sea, northwest of Ōyano Island , Kumamoto Prefecture, 32°37′01"N, 130°23′01"E (St. AG 17, Fig. 1I View Fig ), 58 m depth, sandy bottom, using Smith-McIntyre grab, 15 May 2006, coll. K. Mori; GoogleMaps male (OMNH-Ar-10819), 3.0 mm, GoogleMaps ovigerous female (OMNH-Ar-10820), 3.3 mm, and GoogleMaps female (OMNH-Ar-10821), 2.2 mm, Sagami Bay, southwest of Miura City , Kanagawa Prefecture, 35°07′35"N, 139°33′43"E– 35°07′33"N, 139°33′00"E ( Fig. 1C View Fig ), 102–111 m depth, using dredge, 26 April 2016, coll GoogleMaps . H GoogleMaps . Kohtsuka; male (OMNH-Ar-10822), 2.0 mm, Sagami Bay, southwest of Miura City , Kanagawa Prefecture, 35°09′09"N, 139°34′50"E– 35°08′57"N, 139°34′00"E ( Fig. 1C View Fig ), 76–80 m depth, using dredge, 26 April 2016, coll GoogleMaps . H GoogleMaps . Kohtsuka .

Diagnosis. Eyes large, round. Maxilla 1 outer plate bearing 9 terminal robust setae. Maxilla 2 inner plate with mediofacial row of setae. Male gnathopod 2, basis widened distally, propodus robust, posterior margin weakly setose, with short proximal and distal projections. Pereopod 4 basis slightly expanded. Pereopod 7 carpus about 1.9 times length of propodus. Uropod 2 outer ramus about 0.85 times as long as inner ramus.

Description of male [based mostly on holotype (OMNH-Ar-10812), 5.1 mm, supplemented by paratype (OMNH-Ar-10813), 4.9 mm for coxa 1 and paratype (OMNH-Ar-10819), 3.0 mm for antennae and pereopods 6, 7]. Body ( Fig. 6 View Fig ), dorsal margins of pereonites and pleonites weakly corrugated, urosomite 1 about 1.35 times length of pleonites 2+3. Eyes round, about one third length of head.

Antenna 1 [ Figs 7A View Fig , 10 View Fig ; most parts lost in all specimens, but remained when taking photograph in paratype, male (OMNH-Ar-10819), 3.0 mm] elongate, almost same length as body; peduncular article 1 with several ventral robust setae, peduncular articles 2, 3 very long; accessory flagellum short, articulation unknown. Antenna 2 ( Figs 7B View Fig , 10 View Fig ; same condition as antenna 1) about 0.7 times length of antenna 1; peduncular article 3 short, with several robust setae anteriorly. Upper lip ( Fig. 7C View Fig ) ordinary. Mandibles ( Fig. 7D, D View Fig 1, E, E1 View Fig ) with length ratio of palp articles 1–3 1.0: 2.1: 1.2, articles 2, 3 each with 6–7 setae; incisor with 7 and 6 cusps, lacinia mobilis with 4 and 2 cusps in left and right, respectively, 4 and 3 accessory blades present in left and right, respectively; molar with spatula-like process in right. Lower lip ( Fig. 7F View Fig ) ordinary. Maxilla 1 ( Fig. 7G, G View Fig 1 View Fig ), palp article 2 bearing 5–6 robust setae apically and several setae dorsally. Maxilla 2 ( Fig. 7H View Fig ), inner plate with distal setae, very thin laterodistal setae and 10 mediofacial setae, outer plate bearing many setae on distal margin. Maxilliped ( Fig. 7I View Fig ), inner plate with 3 apical and 1 mediodistal short robust setae on ventral surface; outer plate bearing 3 slender robust setae mediodistally.

Gnathopod 1 ( Fig. 8A, A View Fig 1 View Fig ) slender; coxa subrectangular; basis with ridge on anterolateral surface, bearing single robust seta medially; merus setose posterodistally and mediodistally; carpus long, with many setae on posterior margin; propodus with many setae posteriorly, medial surface heavily setose; dactylus long, slender, curved posteriorly. Gnathopod 2 ( Fig. 8B View Fig ) robust; coxa wide, subtrapezoidal, ventral margin slightly excavated; basis widened distally, curved anteriorly, anterodistal corner roundly lobate; carpus triangular, weakly setose; propodus long and wide, about 1.2 times as long as head, about 3.2 times length of carpus, posterior margin weakly setose, with proximal projection at about 80° angle to palm and small distal projection, posteroproximal margins of both projections bearing several short setae and several minute setae, respectively; dactylus stout, posterior margin roundly produced proximally.

Pereopod 3 ( Fig. 8C, C View Fig 1 View Fig ), coxa semicircular, gill large; basis slender, about 3.8 times as long as width, with glands in middle to distal parts; merus short. Pereopod 4 ( Fig. 8D, D View Fig 1 View Fig ) longer than pereopod 3; coxa semicircular, gill large; basis slightly expanded, about 2.9 times as long as width, with glands in middle to distal parts; merus longer than that of pereopod 3. Pereopod 5 ( Figs 8E View Fig , 10 View Fig ; same condition as antenna 1) much longer than pereopod 4, slender; gill small. Pereopod 6 ( Fig. 8E, F View Fig ), merus long, carpus almost same length as propodus. Pereopod 7 ( Fig. 8E, G View Fig ) about 1.35 times length of pereopod 6; merus very long, carpus about 1.9 times as long as propodus.

Pleopods ( Fig. 9 View Fig A–C), peduncles progressively longer, each with 2 slender coupling hooks; outer rami slightly longer than inner rami, outer rami with 12, 12, 11 articles and inner rami with 10, 11, 10 articles respectively. Uropod 1 ( Fig. 9D View Fig ), peduncle with mediodistal robust seta; outer ramus about 0.9 times as long as inner ramus, outer ramus with 4 lateral, 3 medial and 1–2 terminal robust setae, inner ramus bearing 2–3 lateral, 6 medial and 1–2 terminal robust setae. Uropod 2 ( Fig. 9D View Fig ) about 0.8 times length of uropod 1; peduncle with 1 lateral and 3 medial robust setae; outer ramus about 0.85 times as long as inner ramus in left, outer ramus with 2 lateral and 3 medial robust setae, inner ramus bearing 3 lateral and 4 medial robust setae. Telson ( Fig. 9D View Fig ) bare.

Description of female [based on paratype (OMNH-Ar-10817), 5.4 mm]. Gnathopod 1 ( Fig. 9E View Fig ) similar to that of male, but coxa narrower and medial surface of basis lined with several robust setae. Gnathopod 2 ( Fig. 9F, F View Fig 1 View Fig ), coxa narrow, trapezoidal; basis straight, anterodistal corner not lobate; carpus pear-shaped, posterior margin heavily setose; propodus about 1.25 times as long as carpus, palm with 3 robust setae, posterior margin and medial surface setose; dactylus slender. Pereopods 3, 4 ( Fig. 9G, G View Fig 1 View Fig , H) same as those of male, but basis of pereopod 3 slightly expanded.

Variation. Gnathopod 2: propodus and dactylus in large male [paratype (OMNH-Ar-10814), 5.9 mm; Fig. 9I View Fig ] similar to those of holotype; in small male [paratype (OMNH-Ar-10819), 3.0 mm; Fig. 9J View Fig ], propodus shorter than that of holotype, posteroproximal projection relatively longer, at about 50° angle to palm. Pereopod 3: bases in large male (OMNH-Ar-10815, 4.4 mm) and small male (OMNH-Ar-10819, 3.0 mm) slender, about 3.85 and 4.05 times as long as width respectively. Pereopod 4: basis in large male (OMNH-Ar-10816, 4.3 mm) weakly expanded, about 2.3 times as long as width; basis in small male (OMNH-Ar-10819, 3.0 mm) slightly expanded, about 2.8 times as long as wide.

Coloration in life ( Fig. 10 View Fig ). Eyes light red; whole body almost transparent, scattered with yellow and brown pigments; distal parts of peduncular articles 2, 3 of antenna 1 white, distal part of pereopod 7 propodus white.

Etymology. From the Latin lati (=broad) and mana (=hand), referring to the wide propodus of the male gnathopod 2.

Remarks. This new species has (1) large eyes, (2) maxilla 2 inner plate bearing mediofacial setae, (3) gills present on coxae 2–5, (4) oostegites of female present on coxae 2–4, (5) not prehensile propodi of pereopods 6, 7 (pereopod 5 unknown), and (6) long outer ramus of uropod 2. These features suggest that this species is included in the genus Dulichia . Dulichia latimana sp. nov. can be distinguished from its congeners by the large propodus of the male gnathopod 2 with weakly setose palm bearing short proximal projection, the pereopod 4 with slightly or weakly expanded basis, and the long carpus of the pereopod 7.

Habitat. Sandy bottom, 50–111 m depth.

Distribution. Japan: the Ariake Sea and Sagami Bay (present study).