Opisa takafuminakanoi Narahara-Nakano, Kakui & Tomikawa, 2016, sp. nov.

• Main Authors: Narahara-Nakano, Yukiko, Kakui, Keiichi, Tomikawa, Ko
• Format: Text
• Language: unknown
• Published: Zenodo 2016
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Amphipoda; Opisidae; Opisa; Opisa takafuminakanoi; Arctic; Canada; Norway; Seta
• Online Access: https://dx.doi.org/10.5281/zenodo.6068955; https://zenodo.org/record/6068955

Opisa takafuminakanoi sp. nov. (Figs 1–2) Material examined. Holotype: NSMT-Cr 24702, mature male (7.6 mm) from off the southeast of Akkeshi Bay (42°48′12″N, 144°55′26″E), depth 114–116 m, R/ V Misago-maru , collected by K. Kakui on 8 July 2011. Paratypes: NSMT-Cr 24703, mature male (10.0 mm); NSMT-Cr 24704, ovigerous female (10.2 mm); NSMT-Cr 24705, ovigerous female (7.8 mm); NSMT-Cr 24706, female (8.4 mm). Data same as for the holotype. Description. Male (holotype, NSMT-Cr 24702). Head, lateral cephalic lobe round; eyes subrectangular. Epimeral plates (Fig. 1 B–D), posterior margin of plate 2 with 2 minute setae; posterodistal corner of plate 3 rounded. Antenna 1 (Fig. 1 E) 0.16 times as long as body length; accessory flagellum 6-articulate; primary flagellum 9- articulate, with calceoli (Fig. 1 F) on articles 3–7; callynophore well-developed, about 20 rows, two fields. Antenna 2 (Fig. 1 G) 5.1 times as long as antenna 1, anterior margin of peduncular article 5 with brush setae, peduncular articles 4 and 5 not swollen; flagellum 56-articulate, with calceoli on articles 1–55. Mouthpart bundle, subquadrate. Upper lip (Fig. 1 H) with rounded distal margin, lacking marginal setae. Mandibles (Fig. 1 J, K): incisor smooth; left lacinia mobilis vestigial, representing robust seta, right lacinia absent; molar setose, not triturative; palp articles 1–3 in length ratio of 1.0: 2.1: 1.7. Maxilla 1 (Fig. 1 L, M): inner plate with 1 plumose and 1 simple setae apically; outer plate with 11 spine-teeth in an 8/3 crown arrangement; terminal article of palp with 6 broad setae and long robust seta. Maxilla 2 (Fig. 1 N): inner plate slender, as long as outer plate. Maxilliped (Fig. 1 O) with one third of segment 3 and dactylus of palp exceeding terminal of outer plate. Gnathopod 1 (Fig. 1 P) with well-developed propodus, bearing developed posterodistal lobe, apical robust setae, and slender setae on palmar margin; dactylus developed, strongly arched, both anterior and posterior margins with slender setae. Gnathopod 2 (Fig. 1 Q–S) with elongate carpus, distal half of posterior margin lined with minute triangular scales; propodus (Fig. 1 S) oblique, posterodistal corner with 4 robust setae; dactylus (Fig. 1 S) short, not reaching palmar corner. Pereopod 3 (Fig. 1 T) with subrectangular coxa. Pereopod 4 (Fig. 2 A) subequal in size to pereopod 3, with welldeveloped posteroventral lobe of coxa. Pereopod 5 (Fig. 2 B) with coxa as long as wide and longer than basis; posteroventral lobes of coxa and basis developed. Pereopod 6 (Fig. 2 C) with weakly bilobed coxa; posteroventral lobe of basis developed. Pereopod 7 (Fig. 2 D) with subquadrate coxa; posteroventral lobe of basis developed. Coxal gills on gnathopod 2 and pereopods 3–7. Pleopods (Fig. 2 E–G) typical for genus. Uropod 1 (Fig. 2 H), peduncle with 1 medial and 5 lateral robust setae; inner ramus with medial robust seta; outer ramus slightly longer than inner ramus, with 2 lateral robust setae. Uropod 2 (Fig. 2 I), peduncle with 1 medial and 3 lateral robust setae; inner ramus marginally bare; outer ramus slightly longer than inner ramus, with 2 lateral robust setae. Uropod 3 (Fig. 2 J), inner ramus with 13 plumose setae on medial margin; outer ramus length 1.1 × inner ramus, 2- articulate, proximal article with 6 medial plumose setae and 2 lateral robust setae. Telson (Fig. 2 K) elongate, cleft for about 85% of length, dorsal surface with 4 robust setae, distal margin incised, with penicillate seta and robust seta on each lobe. Female (Paratype, NSMT-Cr 24703). Similar to male except the following points. Antenna 1 (Fig. 2 L), accessory flagellum 3-articulate, primary flagellum without calceoli. Antenna 2 (Fig. 2 M) subequal in length to antenna 1; flagellum 11-articulate; calceoli absent. Egg number 7. Sequences. Four nucleotide sequences of the paratype (NSMT-Cr 24703) were determined: 28S, LC186947 (1313 bp); H3, LC186948 (328 bp); COI, LC 190497 (639 bp); and 16S, LC186946 (395 bp). Etymology. The species is named in honor of the first author’s husband, Dr. Takafumi Nakano, who greatly supports and encourages the first author. Remarks. Opisa takafuminakanoi sp. nov. is most similar to O. eschrichtii in sharing the following features: 1) epimeral plate 3 with smooth posterior margin, 2) gnathopod 1 large with strongly arched dactylus, 3), palmar margin of gnathopod 1 without “palisade” robust setae (Bousfield 1987), 4) depth of coxa 5 greater than length of basis, and 5) rami of uropod-3 with plumose setae. However, judging from the descriptions and figures by Sars (1895) and Bousfield (1987), the former is distinguished from the latter by the vestigial lacinia mobilis of the left mandible, the developed posterior lobe of the coxa 5, and the absence of marginal robust setae on the inner ramus of uropod 2. : Published as part of Narahara-Nakano, Yukiko, Kakui, Keiichi & Tomikawa, Ko, 2016, Opisa takafuminakanoi, a new species of Opisidae from Hokkaido, Japan (Crustacea: Amphipoda), pp. 335-339 in Zootaxa 4200 (2) on pages 335-338, DOI: 10.11646/zootaxa.4200.2.9, http://zenodo.org/record/182285 : {"references": ["Bousfield, E. L. (1987) Amphipod parasites of fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences, 217, 1 - 37. Derzhavin, A. (1929) [Arctic elements in the fauna of peracarids of the Sea of Japan]. Russische hydrobiologische Zeitschrift, 8, 326 - 329. [In Russian]", "Sars, G. O. (1895) Amphipoda. An account of the Crustacea of Norway with short descriptions and figures of all the species, 1, 1 - 240."]}