Opisa takafuminakanoi, Narahara-Nakano, Yukiko, Kakui, Keiichi & Tomikawa, Ko, 2016

Narahara-Nakano, Yukiko, Kakui, Keiichi & Tomikawa, Ko, 2016, Opisa takafuminakanoi, a new species of Opisidae from Hokkaido, Japan (Crustacea: Amphipoda), Zootaxa 4200 (2), pp. 335-339 : 335-338

publication ID

https://doi.org/ 10.11646/zootaxa.4200.2.9

publication LSID

lsid:zoobank.org:pub:3632C868-9887-4021-81FF-81360C1DA59E

DOI

https://doi.org/10.5281/zenodo.6068955

persistent identifier

https://treatment.plazi.org/id/2905953F-FFF6-FF87-CDAE-C447FB11979F

treatment provided by

Plazi

scientific name

Opisa takafuminakanoi
status

sp. nov.

Opisa takafuminakanoi View in CoL sp. nov.

( Figs 1–2 View FIGURE 1 View FIGURE 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 GoogleMaps . 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 View FIGURE 1 B–D), posterior margin of plate 2 with 2 minute setae; posterodistal corner of plate 3 rounded.

Antenna 1 ( Fig. 1 View FIGURE 1 E) 0.16 times as long as body length; accessory flagellum 6-articulate; primary flagellum 9- articulate, with calceoli ( Fig. 1 View FIGURE 1 F) on articles 3–7; callynophore well-developed, about 20 rows, two fields. Antenna 2 ( Fig. 1 View FIGURE 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 View FIGURE 1 H) with rounded distal margin, lacking marginal setae. Mandibles ( Fig. 1 View FIGURE 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 View FIGURE 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 View FIGURE 1 N): inner plate slender, as long as outer plate. Maxilliped ( Fig. 1 View FIGURE 1 O) with one third of segment 3 and dactylus of palp exceeding terminal of outer plate.

Gnathopod 1 ( Fig. 1 View FIGURE 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 View FIGURE 1 Q–S) with elongate carpus, distal half of posterior margin lined with minute triangular scales; propodus ( Fig. 1 View FIGURE 1 S) oblique, posterodistal corner with 4 robust setae; dactylus ( Fig. 1 View FIGURE 1 S) short, not reaching palmar corner. Pereopod 3 ( Fig. 1 View FIGURE 1 T) with subrectangular coxa. Pereopod 4 ( Fig. 2 View FIGURE 2 A) subequal in size to pereopod 3, with welldeveloped posteroventral lobe of coxa. Pereopod 5 ( Fig. 2 View FIGURE 2 B) with coxa as long as wide and longer than basis; posteroventral lobes of coxa and basis developed. Pereopod 6 ( Fig. 2 View FIGURE 2 C) with weakly bilobed coxa; posteroventral lobe of basis developed. Pereopod 7 ( Fig. 2 View FIGURE 2 D) with subquadrate coxa; posteroventral lobe of basis developed. Coxal gills on gnathopod 2 and pereopods 3–7.

Pleopods ( Fig. 2 View FIGURE 2 E–G) typical for genus.

Uropod 1 ( Fig. 2 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 2 L), accessory flagellum 3-articulate, primary flagellum without calceoli. Antenna 2 ( Fig. 2 View FIGURE 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 View Materials (1313 bp); H3, LC186948 View Materials (328 bp); COI, LC 190497 View Materials (639 bp); and 16S, LC186946 View Materials (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.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Amphipoda

Family

Opisidae

Genus

Opisa

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