Dulichia latimana Ariyama 2019, sp. nov.
Creators: name: Ariyama, Hiroyuki
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Podoceridae
Dulichia
Dulichia latimana

description: Dulichia latimana sp. nov.
(Figs 6–10)
[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), 50 m depth, sandy bottom, using Smith-McIntyre grab, 12 May 2006, coll. K. Mori. 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), 58 m depth, sandy bottom, using Smith-McIntyre grab, 15 May 2006, coll. K. Mori; male (OMNH-Ar-10819), 3.0 mm, ovigerous female (OMNH-Ar-10820), 3.3 mm, and 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), 102–111 m depth, using dredge, 26 April 2016, coll. H. 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), 76–80 m depth, using dredge, 26 April 2016, coll. H. 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), 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, 10; 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, 10; 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) ordinary. Mandibles (Fig. 7D, D 1, E, E1) 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) ordinary. Maxilla 1 (Fig. 7G, G 1), palp article 2 bearing 5–6 robust setae apically and several setae dorsally. Maxilla 2 (Fig. 7H), inner plate with distal setae, very thin laterodistal setae and 10 mediofacial setae, outer plate bearing many setae on distal margin. Maxilliped (Fig. 7I), 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 1) 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) 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 1), 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 1) 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, 10; same condition as antenna 1) much longer than pereopod 4, slender; gill small. Pereopod 6 (Fig. 8E, F), merus long, carpus almost same length as propodus. Pereopod 7 (Fig. 8E, G) about 1.35 times length of pereopod 6; merus very long, carpus about 1.9 times as long as propodus.
Pleopods (Fig. 9 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), 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) 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) bare.
Description of female [based on paratype (OMNH-Ar-10817), 5.4 mm]. Gnathopod 1 (Fig. 9E) similar to that of male, but coxa narrower and medial surface of basis lined with several robust setae. Gnathopod 2 (Fig. 9F, F 1), 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 1, 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] similar to those of holotype; in small male [paratype (OMNH-Ar-10819), 3.0 mm; Fig. 9J], 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). 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).
description: Published as part of Ariyama, Hiroyuki, 2019, Four Species of Dulichiidae (Crustacea: Amphipoda) from Japan, with the Description of a New Genus and Two New Species, pp. 29-48 in Species Diversity 24 (1) on pages 32-40, DOI: 10.12782/specdiv.24.29, http://zenodo.org/record/4585163