A new species and new record of the genus Sinocorophium (Crustacea, Amphipoda, Corophiidae) from Korean Waters Author Kim, Young-Hyo text Zootaxa 2017 2017-08-28 4312 1 155 164 journal article 32285 10.11646/zootaxa.4312.1.7 8a173e64-7f56-4310-9046-e48062533e20 1175-5326 852218 A07Eb0B2-D5A8-4403-9A93-41Dd32E910Fd Sinocorophium jindoense sp. nov. (Korean Name: Jin-do-baem-yeop-sae-u, new) ( Figs. 1–4 ) 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. 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 A, 2A) about 4.3 mm long; head about 1.9 × longer than pereonite 1; rostrum ( Fig. 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 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. FIGURE 1. Sinocorophium jindoense sp. nov. , A, paratype, adult male, 7.1 mm, habitus, lateral; B, paratype, adult female, 6.7 mm, habitus, lateral. Scale bars = 2.0 mm (A, B) Antenna 2 ( Fig. 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 E) inner lobe subovate; mandibular process small and blunt; inner and outer lobes with patch of pubescence apically. Left mandible ( Fig. 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. FIGURE 2. Sinocorophium jindoense sp. nov. , holotype, adult male, 4.3 mm, cat no. NIBRIV0000728261: A, habitus, lateral; B, head, dorsal; C, antenna 1; D, antenna 2; E, lower lip; F, left mandible; G, right mandible; H, maxilla 1; I, maxilla 2; J, maxilliped. Scale bars = 0.5 mm (A), 0.4 mm (D), 0.2 mm (B, C), 0.05 mm (E–J). Right mandible ( Fig. 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 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 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 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 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 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 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 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 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 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 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 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 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 H) peduncle slightly longer than rami, with apicodistal robust setae; rami subequal in length, with robust setae marginally. Uropod 3 ( Fig. 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 H) fleshy, thickened, truncate distally. Adult female, cat no. NIBRIV0000728262. Body ( Figs. 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 B). Antenna 1 ( Fig. 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 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. FIGURE 3. Sinocorophium jindoense sp. nov. , holotype, adult male, 4.3 mm, cat no. NIBRIV0000728261: A, gnathopod 1; B, gnathopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pereopod 6; G, pereopod 7; H, urosomites, uropods, and telson. Scale bars = 0.2 mm (A–H). FIGURE 4. Sinocorophium jindoense sp. nov. , paratype, adult female, 4.0 mm, cat no. NIBRIV0000728262: A, habitus, lateral; B, head, dorsal; C, antenna 1; D, antenna 2. Scale bars = 0.5 mm (A), 0.2 mm (B–D). 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 ). Distribution. Korea (Jindo Island).