Guernea namhaensis, Kim, Young-Hyo, Hendrycks, Ed A. & Lee, Kyung-Sook, 2011

Kim, Young-Hyo, Hendrycks, Ed A. & Lee, Kyung-Sook, 2011, The genus Guernea Chevreux, 1887 from Korean waters (Crustacea: Amphipoda: Dexaminidae), Zootaxa 3104, pp. 1-25 : 16-21

publication ID	https://doi.org/ 10.5281/zenodo.204467
DOI	https://doi.org/10.5281/zenodo.6191768
persistent identifier	https://treatment.plazi.org/id/1E0187EC-FFC2-FFFF-FF6D-F86DB111C9A6
treatment provided by	Plazi
scientific name	Guernea namhaensis
status	sp. nov.

Treatment

Guernea namhaensis View in CoL sp. nov.

(Korean Name: Nam-hae-but-eun-kko-ri-yeop-sae-u, new) ( Figs. 2 View FIGURE 2. A C, 11–13)

Type material. Holotype, adult male, 3.3 mm, (appendages on one slide), cat. no. NIBRIV0000240791, Namchang, Haenam-gun, 34° 24ʹ 0 8ʺN, 126° 37ʹ 38ʺE, 20 May 1998, (C.M. Lee & Y.H. Kim), collected from light trap on bottom, depth 8 m. Paratypes, 1 Ƥ, 4.0 mm, dissected (appendages on one slide), NIBRIV0000240792, other data same as holotype; 1 adult 3, 2.3 mm, CMNC 2011-0184, Chubongdo Is. Tongyeong-si, 34° 45ʹ 0 7ʺN, 128° 33ʹ 25ʺE, 10 July 1998, (C.M. Lee), collected from light trap on bottom, depth 5 m.

Additional material examined. 4 3, Nohwado Is., Wando-gun, 23 May 1998, (C.M. Lee); 4 3, Chubongdo Is. Tongyeong-si, 10 July 1998, (C.M. Lee); 1 3, yeompo, Oenarodo Is., 30 July 2001; 4 3, Haban, Oenarodo Is., 30 July 2001; 1 3, Bangjukpo, Dolsando Is., 20 Mar, 2004; 1 3, Paengmok, Jindo Is., 28 June 2004.

Etymology. The specific epithet namhaensis originates from the Korean word “Nam-Hae”, meaning the South Sea, after the southern Korean coast in which the species was discovered.

Diagnosis. Lateral cephalic lobe extending far beyond end of peduncular article 1 of antenna 1, apically narrow; maxilla 1, inner plate small, lacking apical seta, palp uniarticulate; pleonites weakly carinate; urosomite 1 with well developed, rounded dorsal keel, extending backward above following urosomite; urosomites 2–3 distally truncated, ridged laterally, margins with 5–6 spines, dorsal surface hollowed with transverse row of anterior spines.

Description. Holotype, adult male, 3.3 mm, cat no. NIBRIV0000240791.

Body ( Figs. 2 View FIGURE 2. A C, 11A) strongly chitinized; cephalon subequal in length to pereonites 1–2 combined; rostrum triangular, somewhat apically protruded between antenna 1; eye medium, bulging, each ommatidium concentrated in the center; lateral cephalic lobe narrowly rounded, extending far beyond end of article 1 of antenna 1.

Pleonites 1–3 ( Fig. 11 View FIGURE 11 B) weakly carinate; epimeron 1 with anterior sinus, slightly produced anteroventrally, with 1 small seta; epimeron 2 rounded anteroventrally, with 5 small setae ventrally; epimeron 3 similar to pleonal epimeron 2, but smaller and less concave posterodorsally, posterior margin nearly straight.

Urosomite 1 ( Fig. 11 View FIGURE 11 C) dorsal carination broadly rounded, slightly extending over urosomites 2–3; urosomites 2–3 with 5–6 pairs of spines on the lateral ridge, sloped dorsal margin with a transverse row of 4–5 spines.

Antenna 1 ( Fig. 11 View FIGURE 11 D) about twice as long as cephalon and pereonite 1 combined; length ratio of peduncular articles 1–3 = 1.00: 0.55: 0.24, peduncular article 1 slightly sinuate dorsally, with middorsal hump, convex ventromedially, with 2 thin, long simple setae and numerous long setular tufts; flagellum 8-articulate, slightly shorter than peduncle.

Antenna 2 ( Fig. 11 View FIGURE 11 E) 1.53 x as long as antenna 1; gland cone well developed, article 4 swollen posteromedially, 1.28 x as long as article 5, with numerous setular tufts anteriorly; flagellum 13-articulate (broken), longer than peduncle.

Lower lip ( Fig. 11 View FIGURE 11 F) inner lobes well developed, fused basally, outer lobes with 1 small apical tooth on shoulders; both lobes densely pubescent apically.

Right mandible ( Fig. 11 View FIGURE 11 G) smooth, triangular; incisor broad, rounded apically; lacinia mobilis bifid, with 2 smooth teeth; molar process very large, protruding, strongly sclerotized, with 1 pappose seta.

Maxilla 1 ( Fig. 11 View FIGURE 11 H) inner plate small, without seta; outer plate with 9 tooth-like spines (simple, bifid and denticulate) apically; palp uniarticulate, extending past outer plate, with 5 simple setae and an acute tooth apically.

Maxilla 2 ( Fig. 11 View FIGURE 11 I) inner plate much shorter than outer, medial and apical margin with 5 simple setae; outer plate with 7 apical simple setae and 1 sub-medial short seta on lateral margin.

Maxilliped ( Fig. 11 View FIGURE 11 J) inner plate small, with 2 apical setae; outer plate large, broad, extending beyond end of palp article 2, medial margin with 5 setae and 9 conical teeth; palp 4-articulate, proximal article with 1 long seta posterodistally, medial margin of article 2 with 12 simple and 5 pinnate setae, article 3 0.36 x as long as article 2, medial margin setose, article 4 very short, 0.18 x as long as article 3.

Gnathopod 1 ( Fig. 12 View FIGURE 12 A) coxa tapering distally, with feeble setae ventrally; basis slightly S-shaped proximally, gradually widening; anterior margin of merus very short, concealed by the abutment of carpus; carpus elongate, triangular, subequal in length to propodus, with 10 simple or pinnate setae posteriorly; propodus subrectangular, medial side with 1 angled row of 5 unipinnate setae, palm 0.60 x as long as ventral margin, with tiny setules marginally, corner delimited by 4 spines distally; dactylus falcate, 0.41 x as long as propodus, inner margin with 1 distinct tooth.

Gnathopod 2 ( Fig. 12 View FIGURE 12 B) similar to gnathopod 1, but coxa 2 larger than coxa 1, basis not curved proximally, merus tapering distally, carpus and propodus more slender.

Pereopod 3 ( Fig. 12 View FIGURE 12 C) slender, linear, coxa 3 similar to coxa 2, with 9 feeble setae ventrally; both margins of merus setose, posterior margin of carpus with 5 spines; length ratio of articles 2–7 = 1.00: 0.23: 0.59: 0.33: 0.40: 0.18.

Pereopod 4 ( Fig. 12 View FIGURE 12 D) similar to pereopod 3, but less setose, coxa 4 slightly wider, posterior margin slightly concave, basis distinctly shorter; length ratio of articles 2–7 = 1.00: 0.28: 0.72: 0.38: 0.51: 0.28.

Pereopod 5 ( Fig. 12 View FIGURE 12 E) coxa bilobate, 0.90 x as wide as long, posterior lobe broadly rounded, protruding downward; basis broad, bulging midanteriorly, 1.74 x as long as merus; ischium to dactylus slender, length ratio of articles 4–7 = 1.00: 0.79: 0.74: 0.40.

Pereopod 6 ( Fig. 12 View FIGURE 12 F) coxa small, bilobate, slightly concave ventral margin; basis 0.90 x as wide as long, anterior margin rather straight, posterior margin expanded, convex, with 5 feeble setules; merus with 1 spine and 5 plumose setae anteriorly, 7 plumose setae posteriorly; length ratio of articles 4–7 = 1.00: 0.79: 0.80: 0.41.

Pereopod 7 ( Fig. 12 View FIGURE 12 G) coxa subrectangular, longer than wide; basis broad, greatly expanded, anterior margin straight, posterior margin rounded, 0.79 x as wide as long; merus and carpus expanded broadly, with plumose, simple, pinnate setae and spines on both margins; propodus slender, subequal in length to carpus.

Uropod 1 ( Fig. 12 View FIGURE 12 H) peduncle longer than rami, length 1.71 x outer ramus, medial margin with 4 spines; outer ramus 1.13 x as long as inner; inner ramus with 4 medial spines and 1 basofacial seta; both rami with long apical spine.

Uropod 2 ( Fig. 12 View FIGURE 12 I) about 0.6 x as long as uropod 1; peduncle about 1.5 x as long as outer ramus, with 5 dorsolateral and 1 ventrodistal spine; outer ramus 0.9 x as long as inner one, with 4 outer, 2 subapical and 2 apical spines; inner ramus with 2 outer, 1 inner, 2 subapical and 1 long apical spine.

Uropod 3 ( Fig. 12 View FIGURE 12 J) slightly shorter than uropod 1; peduncle stout, about 0.8 x as long as rami; both rami subequal in length, with outer spines and inner plumose setae.

Telson ( Fig. 12 View FIGURE 12 K) subtriangular, narrowing distally, deeply cleft, about 1.6 x as long as wide, dorsomedian surface of each lobe with 1 pair of supple setae, half of dorsodistal surface covered with 7–9 pappose setae and 4 feeble marginal setae.

Paratype, adult female, 4.0 mm, cat no. NIBRIV0000240792.

Body ( Fig. 13 View FIGURE 13 A) stouter than male. Eye ( Fig. 13 View FIGURE 13 B) rounded, bulging, smaller than that of male; lateral cephalic lobe not extending beyond article 2 of antenna 1. Pereonites somewhat broader than in male, while pleonites ( Fig. 13 View FIGURE 13 C) narrower. Pleonite 1 more tapering distally than that of male. Urosomite 1 process narrower and raised slightly higher, extending backward above following urosomite dorsodistally. Sloped dorsal quadrate plane of urosomites 2–3 ( Fig. 13 View FIGURE 13 D) enclosed by spines, except ventral margin.

Antenna 1 ( Fig. 13 View FIGURE 13 E) about 1.3 x as long as cephalon; shorter and stouter than in male, length ratio of peduncular articles 1–3 = 1.00: 0.44: 0.20, article 1 naked, slightly sinuate dorsally, with middorsal hump, with 2 tiny plumose setae posterodistally; flagellum 6-articulate, about half length of peduncle.

Antenna 2 ( Fig. 13 View FIGURE 13 F) slightly shorter than antenna 1, peduncular article 4 long, naked, more than twice length of article 5; flagellum very short, 3-articulate.

Pereopod 5 ( Fig. 13 View FIGURE 13 G) similar to male, but coxa wider, about 0.8 x as wide as long, anteromedian margin of basis with 19 plumose setae.

Uropod 3 ( Fig. 13 View FIGURE 13 H) peduncle subequal in length to rami, with 1 apicolateral spine; rami subequal in length, outer ramus with 4 dorsolateral spines, inner with 2 dorsolateral spines.

Telson ( Fig. 13 View FIGURE 13 I) triangular, deeply cleft, about 1.5 x as long as wide, dorsal surface of each lobe with 6–7 pappose spines, lateral margin with 3–4 tiny setae, 1 penicillate seta lateromedially and distally with 1 pappose spine.

Remarks. Guernea namhaensis is similar to G. tomiokaensis Hirayama, 1985 from Japanese waters, in possessing a similar shaped dorsal keel of urosomite 1 and having the lateral cephalic lobe extending far beyond peduncular article 1 of antenna 1. However, our species is obviously distinguished from G. tomiokaensis (different characters of G. tomiokaensis in brackets) by the following group of features: 1) inner plate of maxilliped small, with 2 apical setae and the distal article of palp bears 2 small apical setae (vs inner plate vestigial, with 1 short apical seta and the distal article of palp bears 1 small apical seta); 2) posterior lobe of coxa 5 broadly rounded, extending strongly downward (vs not extending downward); 3) urosomite 1 extends backward above following urosomite dorsodistally (vs not extended backward above following urosomite); 4) urosomites 2–3 quadrate in dorsal view, sloped plane with 5 or 6 pairs of lateral spines and 1 transverse row of 4 or 5 dorsal spines (vs triangular in dorsal view, only with 5 opposite pairs of lateral spines); and 5) peduncle of uropod 3 subequal in length to rami (vs peduncle 0.6 x as long as rami).

The new species is also similar to Guernea sombati Hirayama, 1986 from the South China Sea and Hong Kong. Our new species however, is distinguished from G.. s o m b a t i (different characters of G.. sombati in brackets) by the following features: 1) lateral cephalic lobe extending far beyond peduncular article 1 of antenna 1 (vs extending to near the end of peduncular article 1 of antenna 1); 2) in male, antenna 1 peduncle longer than flagellum (vs shorter than flagellum); 3) in male, antenna 2 peduncular article 4 swollen (vs relatively slender); 4) in male, antenna 2 peduncular article 5 relatively slender and elongate, 0.78 x as long as article 4 (vs short, about 0.5 x as long as article 4); 5) in female, antenna 1 peduncular article 2 short and stout, 0.44 x as long as article 1 (vs elongate, about 0.8 x as long as article 1); and 6) urosomites 2–3 with 5 or 6 pairs of lateral spines and a transverse row of 4 or 5 dorsal spines (vs 5 spines on each of the dorsal ridges).

Distribution. Korea (south coast).