Sinocorophium jindoense, Kim, 2017

Kim, Young-Hyo, 2017, A new species and new record of the genus Sinocorophium (Crustacea, Amphipoda, Corophiidae) from Korean Waters, Zootaxa 4312 (1), pp. 155-164 : 156-160

publication ID	https://doi.org/ 10.11646/zootaxa.4312.1.7
publication LSID	lsid:zoobank.org:pub:A07Eb0B2-D5A8-4403-9A93-41Dd32E910Fd
DOI	https://doi.org/10.5281/zenodo.6002150
persistent identifier	https://treatment.plazi.org/id/039BC259-FFBB-7736-FF05-EF45601BF897
treatment provided by	Plazi
scientific name	Sinocorophium jindoense
status	sp. nov.

Treatment

Sinocorophium jindoense View in CoL sp. nov.

(Korean Name: Jin-do-baem-yeop-sae-u, new) ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Type material. Holotype, adult male, 4.3 mm, cat no. NIBRIV0000728261, Sin stream, Jimak-ri , Gogun-myeon, Jindo-gun, Jeollanam-do, Korea, 34° 28′52″N, 126° 21′30″E, 28 April 2015, collected with dredge on bottom, collected by KES. Paratypes, 1 adult female cat. no. NIBRIV0000728262, data same as holotype (dissected), and the remaining paratypes (13 ♂, 39 ♀, DKUAMP201703) in the collection of the corresponding author. GoogleMaps

Habitat. The new species is found in brackish estuary with a water temperature of 23.5 degrees C, salinity of 0.3 PSU, and pH 8.2. Sediment is composed of mud.

Etymology. The species name jindoense is derived from the type locality, Jindo Island located on the southwestern coast of Korea.

Description. Holotype adult male, 4.3 mm, cat no. NIBRIV0000728261.

Body ( Figs. 1 View FIGURE 1 A, 2A) about 4.3 mm long; head about 1.9 × longer than pereonite 1; rostrum ( Fig. 2 View FIGURE 2 B) subpointed distally, triangular in dorsal view, slightly longer than cephalic lobe; eye invisible in alcohol; length ratio of pereonites 1–7 = 1.00: 1.63: 1.50: 2.00: 2.34: 2.25: 1.75; pleonites1–2 with rounded posteroventralcorners, pleonite 3 slightly shorter than pleonites 1 and 2 combined; coxa 1 elongate–ovate, remainder of coxae flat dorsoventrally, much shallower than pereonites; urosomites1–3 separated.

Antenna 1 ( Fig. 2 View FIGURE 2 B, C) longer than head and pereonites 1–5 combined, peduncle 1.32 × longer than flagellum; peduncular article 1 subrectangular, irregularly serrulate medially in dorsal view, with 1 small robust seta ventrodistally and unequal simple setae ventrally; length ratio of peduncular articles 1–3 = 1.00: 0.63: 0.38; flagellum 13-articulate, 0.76 × peduncular articles, with small aesthetascs ventrodistally.

Antenna 2 ( Fig. 2 View FIGURE 2 A, D) massive; peduncular article 4 with 1 large tooth ventrodistally; length ratio of peduncular articles 2–5 = 1.00: 1.33: 3.33: 3.00; flagellum biarticulate, proximal one 0.43 × peduncular article 5, distal one short, about 0.23 × proximal one, with 2 unequal long setae and short cluster of setae apically. Lower lip ( Fig. 2 View FIGURE 2 E) inner lobe subovate; mandibular process small and blunt; inner and outer lobes with patch of pubescence apically.

Left mandible ( Fig. 2 View FIGURE 2 F) well developed, incisor with 3 blunt teeth, lacinia mobilis with 5 teeth; accessory setal row with 2 denticulate blades and 2 simple setae; molar well developed, truncate, triturative; palp missing.

Right mandible ( Fig. 2 View FIGURE 2 G) similar to left mandible, incisor and lacinia mobilis produced inward, bluntly tridentate; palp biarticulate, proximal article slightly shorter than distal, with 1 plumose seta apically, distal article slender, with long plumose seta apically.

Maxilla 1 ( Fig. 2 View FIGURE 2 H) inner plate unknown; outer plate armed with 7 setal-teeth (simple or serrulate) apically; palp biarticulate, article 1 short, article 2 slender, strongly extending beyond end of outer plate.

Maxilla 2 ( Fig. 2 View FIGURE 2 I) inner plate with longitudinal row of plumose setae on inner margin, subdistal and apical margins with row of simple setae; outer plate extending beyond end of inner plate, subdistal and apical margins with simple or plumose setae.

Maxilliped ( Fig. 2 View FIGURE 2 J) inner plate slender, subrectangular, with 1 subapical and terminal setae; outer plate near reaching distal end of article 2 of palp, inner margin straight with row of setae, outer margin pubescent, curved convexly; palp 4-articulate, proximal article with 1 long plumose seta on outer margin, inner margin with densely simple setae, outer margin with 1 simple seta distally, article 3 subrectangular, article 4 short and blunt, length ratio of articles 1–4 = 1.00: 1.93: 0.91: 0.17.

Gnathopod 1 ( Fig. 3 View FIGURE 3 A) subchelate; coxa elongate-ovate, with 3 long plumose setae ventrally, anterior margin with 4 unequal setae; basis posterodistal corner with 2 short simple setae; ischium square, with long plumose setae ventrodistally; merus short, subtriangular, with long plumose setae ventrodistally; carpus with 2 simple setae midanteriorly, distomedial corner with transverse row of simple setae, posterior margin with 2 rows of pinnate setae; propodus subrectangular, proximal half of both margins slightly concave, with simple setae marginally, palm transverse, lined with row of bifid spinules; dactylus falcate, nearly fitting palm; length ratio of 2–7 articles = 1.00: 0.24: 0.22: 1.04: 0.75: 0.22.

Gnathopod 2 ( Fig. 3 View FIGURE 3 B) simple; coxa small; basis subrectangular, with 2 long simple setae posterodistally; merus convexly curved posteriorly, with 2 rows of long plumose setae along posterior margin and medial portion; carpus isosceles triangle in shape, strongly widening distally, with several simple and plumose setae posterodistally; propodus both margins with simple setae, proximal half of medial region with oblique row of plumose setae; dactylus long and falcate; length ratio of 2–7 articles = 1.00: 0.16: 0.84: 0.76: 1.20: 0.70.

Pereopod 3 ( Fig. 3 View FIGURE 3 C) basis weakly expanded medially; merus slightly widening distally; propodus thin and long, narrow distally; dactylus slender; length ratio of 2–7 articles = 1.00: 0.21: 0.50: 0.37: 0.42: 0.32.

Pereopod 4 ( Fig. 3 View FIGURE 3 D) similar to pereopod 3; length ratio of 2–7 articles = 1.00: 0.23: 0.48: 0.31: 0.42: 0.40.

Pereopod 5 ( Fig. 3 View FIGURE 3 E) much shorter and of different structure than pereopod 4; basis anteromarginally with several setae; merus with row of unequal simple setae anteriorly, anterodistally with 4 plumose setae, posterior margin with 3 plumose setae, posterodistally with 1 simple seta and 2 plumose setae; carpus subtriangular, with 2 oblique rows of 4 proximal and 7 distal robust setae respectively; propodus slender; dactylus short; length ratio of 2–7 articles = 1.00: 0.30: 0.60: 0.28: 0.28: 0.15.

Pereopod 6 ( Fig. 3 View FIGURE 3 F) similar to pereopod 5, but longer; basis with a row of plumose setae posteriorly; merus anterior margin with a row of simple setae, anterodistally with 4 plumose setae, with several plumose setae posteriorly; carpus subtriangular, with 2 oblique rows of 3 proximal and 8 distal robust setae respectively; propudus slender; dactylus short; length ratio of 2–7 articles = 1.00: 0.22: 0.69: 0.31: 0.34: 0.17.

Pereopod 7 ( Fig. 3 View FIGURE 3 G) elongate, greatly longer than either pereopod 5 or 6; basis elongate-ovate, 0.46 × wider than long, densely setose along both margins with long plumose setae; length ratio of 2–7 articles = 1.00: 0.30: 0.66: 0.62: 0.84: 0.38.

Urosomites 1–3 ( Fig. 3 View FIGURE 3 H) separate; urosomite 1 longest, widest and slightly curved dorsally; urosomite 2 much wider than urosomite 3, posterodistal margins rounded in dorsal view; uropods 1–3 arising laterally.

Uropod 1 ( Fig. 3 View FIGURE 3 H) extending beyond end of uropod 2; peduncle subrectangular, 1.52 × outer ramus, with row of 5 short stout seate laterally, 3 robust setae medially; outer ramus 1.50 × longer than inner.

Uropod 2 ( Fig. 3 View FIGURE 3 H) peduncle slightly longer than rami, with apicodistal robust setae; rami subequal in length, with robust setae marginally.

Uropod 3 ( Fig. 3 View FIGURE 3 H) uniramous, peduncle short, widening distally, subequal to ramus, both distal margins with simple setae; ramus ovate, margin surrounded by simple setae.

Telson ( Fig. 3 View FIGURE 3 H) fleshy, thickened, truncate distally.

Adult female, cat no. NIBRIV0000728262.

Body ( Figs. 1 View FIGURE 1 B, 4A) about 4.0 mm long, length ratio of pereonites 1–7 = 1.00: 1.71: 1.71: 2.07: 2.86: 2.71: 2.14; similar to male except short length of antenna 2 and wider rostrum ( Fig. 4 View FIGURE 4 B).

Antenna 1 ( Fig. 4 View FIGURE 4 C) similar to that of male; peduncular article 1 rectangular, with unequal simple setae posteriorly and a robust seta posterodistally; length ratio of peduncular articles 1–3 = 1.00: 0.55: 0.31; flagellum 11-articulate, 0.81 × peduncular articles, small aesthetascs ventrodistally.

Antenna 2 ( Fig. 4 View FIGURE 4 D) similar in shape but stouter and shorter than that of male, especially peduncular articles 3 and 4; length ratio of peduncular articles 2–5 = 1.00: 1.41: 3.15: 2.63; flagellum biarticulate, proximal one 0.51 × peduncular article 5, distal one short, 0.22 × proximal one.

Remarks. The new species Sinocorophium jindoense sp. nov. is similar to S. hangangense and S. monospinum having the following characteristics: 1) antenna 2, peduncular article 4 with 1 ventrodistal tooth; 2) antenna 2, peduncular article 4 elongate, width less than 0.5 × length; 3) gnathopod 1, palm gently convex; 4) pereopods 3–4, merus longer than carpus; and 5) uropod 1, inner ramus shorter than outer. However, Sinocorophium jindoense sp. nov. is distinguished from its congeners based upon the following features: 1) head, rostrum subpointed distally (vs. pointed in S. hangangense and S. monospinum ); 2) mandibular palp biarticulate (vs. triarticulate in S. monospinum ); 3) pereopods 3–4, merus less than twice length of carpus (vs. twice length of carpus in S. monospinum ); 4) pereopods 5–6, merus with plumose setae (vs. simple setae in S. hangangense and S. monospinum ); 5) uropod 1, lateral margin of peduncle with robust setae (vs. with simple setae in S. hangangense ); 6) uropod 1, inner ramus slightly shorter than outer (vs. much shorter than outer in S. monospinum ); and 7) uropod 3, ramus subequal to peduncle (vs. longer than peduncle in S. hangangense ).