Dulichia biarticulata Hirayama and Takeuchi, 1993

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 : 31-32

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.4734560
persistent identifier	https://treatment.plazi.org/id/1B069A22-FFCA-442B-39B9-FDF4FB84FC9F
treatment provided by	Felipe
scientific name	Dulichia biarticulata Hirayama and Takeuchi, 1993
status

Treatment

Dulichia biarticulata Hirayama and Takeuchi, 1993 ( Figs 2–5 View Fig View Fig View Fig View Fig )

[Japanese name: Kishi-shakutoridoronomi, new]

Dulichia biarticulata Hirayama and Takeuchi, 1993: 160 , figs 15, 16.

Material examined. Two males (OMNH-Ar-10798, 10799), 3.1 and 2.4 mm, and female (OMNH-Ar-10800), 2.7 mm, Kitsunezaki-hama, Ishinomaki City , Miyagi Prefecture, 38°21′21"N, 141°25′23"E ( Fig. 1A View Fig ), 3 m depth, rocky reef, using SCUBA, 3 October 2017, coll GoogleMaps . M GoogleMaps . Aoki; male (OMNH-Ar-10801), 3.1 mm, Akinohama Beach, Izu Oshima Island ( Oshima Town ), Tokyo Prefecture, 34°47′13"N, 139°24′31"E ( Fig. 1F View Fig ), 8 m depth, rocky reef, using SCUBA, 4 May 2017, coll GoogleMaps . O GoogleMaps . Hoshino ; male (OMNH-Ar-10802), 4.8 mm, same place, 6 May 2017, coll . O . Hoshino ; male (OMNH-Ar-10803), 2.9 mm, and 2 ovigerous females (OMNH-Ar-10804, 10805), 4.8 and 3.5 mm, same place, 9 May 2017, coll . O . Hoshino; male (OMNH-Ar-10806), 3.5 mm, Moroiso, Miura City , Kanagawa Prefecture ( Fig. 1D View Fig ), 3 m depth, rocky reef, using SCUBA, 25 December 2014, coll . H . Kohtsuka; 2 males (OMNH-Ar-10807, 10808), 3.8 and 2.1 mm, and female (OMNH-Ar-10809), 2.7 mm, Kodomari, Takahama Town , Fukui Prefecture, 35°32′10"N, 135°30′56"E ( Fig. 1G View Fig ), 10 m depth, among a brown alga Sargassum macrocarpum , using SCUBA, 29 February 1980, coll GoogleMaps . H GoogleMaps . Ariyama and H . Nakahara ; male (OMNH-Ar-10810), 2.8 mm, same place, 25 April 1980, coll . H . Ariyama and H . Nakahara; male (OMNH-Ar-10811), 2.8 mm, Tanigawa, Misaki Town , Osaka Prefecture, 34°19′25"N, 135°07′10"E ( Fig. 1H View Fig ), 5 m depth, on a tunicate Halocynthia ritteri (Oka, 1906) , using SCUBA, 29 May 1996, coll GoogleMaps . H GoogleMaps . Ariyama.

Diagnosis. Eyes large, round. Accessory flagellum 2-articulate. Maxilla 1 outer plate bearing 9 terminal robust setae. Maxilla 2 inner plate with mediofacial row of setae. Male gnathopod 2, basis relatively wide, propodus large, posterior margin weakly setose, bearing proximal and distal projections changeable with growth. Pereopod 4 basis expanded. Pereopod 7 carpus about 1.4 times as long as propodus. Uropod 2 outer ramus about 0.8 times length of inner ramus.

Description of male [based on male (OMNH-Ar-10801), 3.1 mm]. Body ( Fig. 2 View Fig ), dorsal margins of pereonites and pleonites smooth, urosomite 1 about 1.35 times as long as pleonites 2+3. Eyes round, about 0.3 times length of head. Antenna 1 ( Figs 2 View Fig , 3A View Fig ) about 0.8 times as long as body, accessory flagellum 2-articulate. Antenna 2 ( Fig. 2 View Fig ) about 0.7 times length of antenna 1.

Gnathopod 1 ( Fig. 3B View Fig ), basis with ridge on anterolateral surface; merus setose posterodistally; carpus with many setae on posterior margin; propodus with many setae posteriorly, medial surface also setose; dactylus curved posteriorly. Gnathopod 2 ( Fig. 3C View Fig ), coxa wide, larger than coxa 1, subtrapezoidal, ventral margin slightly excavated; basis relatively wide, anterodistal corner a little lobate; carpus triangular, posterodistal corner setose; propodus large, about 0.7 times as long as head, about 2.1 times length of carpus, posterior margin weakly setose, bearing distally-oriented proximal projection and distal projection each with minute setae; dactylus stout, posterior margin produced proximally.

Pereopod 3 ( Fig. 3D, E View Fig ), basis weakly expanded, about 2.2 times as long as width, with glands in most part; merus short. Pereopod 4 ( Fig. 3D, F View Fig ) longer than pereopod 3; basis strongly expanded, about 1.6 times as long as width, with glands in central part; merus longer than that of pereopod 3. Pereopod 5 ( Fig. 3G, G View Fig 1 View Fig ), basis slender, merus short, carpus about 0.85 times as long as propodus. Pereopod 6 ( Fig. 3H View Fig ) about 1.1 times length of pereopod 5; basis slightly expanded, merus short, carpus about 0.9 times as long as propodus. Pereopod 7 ( Fig. 3H, I View Fig ) about 1.3 times length of pereopod 6; basis slightly expanded, merus long, carpus about 1.4 times as long as propodus.

Description of female [based on female (OMNH-Ar-10805), 3.5 mm]. Gnathopod 1 ( Fig. 4A View Fig ) similar to that of male. Gnathopod 2 ( Fig. 4B, B View Fig 1 View Fig ), coxa narrower than male coxa 2, 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 single robust seta, posterior margin and medial surface setose; dactylus slender. Pereopods 3, 4 ( Fig. 4C, D View Fig ) almost same as those of male, bases weakly expanded, about 2.3 and 1.9 times as long as width respectively.

Variation. Gnathopod 2: propodi and dactyli in very large male (OMNH-Ar-10802, 4.8 mm; Fig. 4E View Fig ) and large male (OMNH-Ar-10807, 3.8 mm; Fig. 4F View Fig ) longer than those of male (OMNH-Ar-10801, 3.1 mm; Fig. 3C View Fig ), proximal projections of propodi also long and situated more proximally, right-angled to palm in very large male and at about 45° angle to palm in large male; propodi and dactyli in male (OMNH-Ar-10803, 2.9 mm; Fig. 4G View Fig ) and small male (OMNH-Ar-10808, 2.1 mm; Fig. 4H View Fig ) almost same as those of male (OMNH-Ar-10801, 3.1 mm; Fig. 3C View Fig ). Pereopod 3: bases in very large male (OMNH-Ar-10802, 4.8 mm) and large male (OMNH-Ar-10807, 3.8 mm) slender, about 4.1 and 3.45 times as long as width respectively. Pereopod 4: bases in those males weakly expanded, about 2.6 and 2.35 times as long as width respectively.

Coloration in life ( Fig. 5 View Fig ). Eyes dark red; dorsal part of body pale brown, ventrolateral part of body beige, scattered with small brown pigments; distal part of peduncular article 3 and proximal part of flagellar article 1 of male antenna 1 white. Whole body except for eyes orange in some large females.

Remarks. The morphological characters of the specimens are very similar to those of the original descriptions and figures of Dulichia biarticulata . Although Hirayama and Takeuchi (1993) stated “in pereopods 5 and 7, propodi clearly longer than carpi”, the fig. 16P (lower) in their paper is not the left pereopod 7 and the fig. 16O (upper and lower) is also not the left pereopod 6. The figs 16P (lower) and 16O are probably the left pereopod 6 and the right pereopod 7, respectively; therefore, the propodus of the pereopod 7 is shorter than the carpus like my specimens. Hirayama and Takeuchi (1993) described this species based on the male specimen. Morphological characters of the female were firstly described in the present paper.

Habitat. Found on the self-constructed mast on rocky reef ( Fig. 5 View Fig ), on tunicates or among algae, 3–10 m depth.

Distribution. Japan: coasts of Miyagi, Fukushima, Tokyo, Kanagawa, Fukui and Osaka Prefectures ( Hirayama and Takeuchi 1993, present study).