Grandidierella naroensis, Kim & Choi & Kim & Im & Kim, 2024

Kim, June, Choi, Jae-Hong, Kim, Yu-Jin, Im, Hyeong-Woo & Kim, Young-Hyo, 2024, Two new species of the family Aoridae (Crustacea, Malacostraca, Amphipoda) from Korean waters, ZooKeys 1210, pp. 117-132 : 117-132

Grandidierella naroensis sp. nov.

Figs 2 B , 6 , 7 , 8 Korean name: Na-ro- do-keun-ap-son-yeop-sae-u, new

Type material.

Holotype, South Korea • 4.9 mm • 1 ♂; Yeom-po beach , Narodo Island, Goheung-gun, Jeollanam-do; 34 ° 25 ' 57 " N, 127 ° 29 ' 31 " E; collected from hand net; 01 April 2022; Y. H. Kim leg.; HNIBRIV 2427 .

Diagnosis.

Antenna 1 slender, elongated. Antenna 2 relatively stout, flagellum short. Gnathopod 1 carpochelate, enlarged, ischium without posterodistal process, merus with weak process posterodistally, carpus with three processes on posterodistal corner, distal and proximal processes short, middle process elongate. Gnathopod 2, carpus longer than propodus, palm steeply angled. Pereopod 6, basis anterior margin with two plumose and three setae. Uropod 1, peduncle lacking inter-ramal process ventrodistally. Uropod 3 uniramus, ramus biarticulate.

Description.

Adult male, HNIBRIV 2427 .

Body (Figs 2 B , 6 A ) 4.9 mm long, subcylindrical, dorsally smooth; eye small, rounded, composed of ommatidia.

Antenna 1 (Fig. 6 B ) slender, elongated; length ratio of peduncular articles 1–3 = 1.00: 1.03: 0.44; flagellum 16 - articulate; accessory flagellum short, 2 - articulate.

Antenna 2 (Fig. 6 C ) shorter than antenna 1; peduncular articles 4 and 5 subrectangular, setose; length ratio of peduncular articles 3–5 = 1.00: 2.85: 3.14; flagellum short, 5 - articulate, each article with 1–2 robust setae ventrally.

Upper lip (Fig. 6 D ) subrounded, apical margin truncate and pubescent.

Lower lip (Fig. 6 E ), inner plate elongate-ovate, pubescent medially and distally; outer plate expanded, distal margin rounded and pubescent; mandibular process well developed.

Right mandible (Figs 6 F, G ), incisor with five blunt teeth and lacinia mobilis with six teeth; accessory setal row composed of seven setae; molar triturative; palp stout, 3 - articulate; article 1 relatively short, unarmed, length 0.58 × article 3; article 2 with five setae medially and one seta laterally, length 0.77 × article 3; article 3 with 13 unipectinate and two simple setae distally and five simple setae laterally.

Left mandible (Fig. 6 H ) similar to right mandible, but lacinia mobilis with four teeth and accessory setal row composed of eight setae.

Maxilla 1 (Fig. 6 I ), inner plate vestigial; outer plate, apical margin with eight dentate setal teeth (two simple, one bifid, two tricuspidate, and three multicuspidate); palp biarticulate, article 1 short, unarmed, article 2 swollen distally, apex round, with five robust and three simple setae.

Maxilla 2 (Fig. 6 J ), inner plate apex and medial margins setose; outer plate subequal to inner plate, with row of distal setae.

Maxilliped (Fig. 6 K ), inner plate subrectangular, mediodistal corner slightly produced, medial margin with five setae, apex with six simple and three stout robust setae; outer plate elongate-ovate, medial margin straight with four blunt robust and four simple setae, apical margin with four robust setae gradually increasing in size; palp 4 - articulate, article 1 subtriangular, article 2 subrectangular, medial margin with long setae, article 3 slender, lateral margin with two setae, subapical margin with 10 setae, article 4 falcate, with a nail.

Gnathopod 1 (Fig. 7 A ) carpochelate, enlarged; coxa small, subquadrate, width 1.36 × length; basis subrectangular, length 1.67 × width, expended posteriorly, widening distally; ischium short, length 0.12 × basis, without posterodistal process; merus located below carpus, with weak process posterodistally; carpus characteristic in form, massive, length 1.54 × width, length 2.01 × merus, with three processes on posterodistal corner, distal and proximal processes short, middle process elongate, with seven setae between middle and proximal processes; propodus subovate, width 0.67 × length, convex posteriorly, length 0.65 × carpus; dactylus falcate, posterior margin with two accessory teeth.

Gnathopod 2 (Fig. 7 B ), coxa subquadrate; basis slender, subrectangular, widening distally; merus located below carpus, length 1.42 × ischium; carpus moderate, elongate-ovate, posterior margin setose; propodus subquadrate, length 0.74 × carpus, posterior margin with three robust setae, palm steeply angled, defined by two robust setae; dactylus falcate, fitting palm.

Pereopod 3 (Fig. 7 C ), coxa subovate; basis elongate, slightly widened in the middle, both margins with four anterior and three posterior short setae; merus widening distally, length 0.71 × basis; carpus slender, short, length 0.59 × merus; propodus slender, narrowing distally, subequal to carpus; dactylus falcate.

Pereopod 4 (Fig. 8 A ) similar to pereopod 3, but coxa with one robust seta on ventral margin.

Pereopod 5 (Fig. 8 B ), coxa wider than long, bilobate; basis subovate, length 1.72 × width, anterior margin with a row of six short setae, posterior margin with three robust setae; merus subrectangular, widening distally, length 1.88 × ischium; carpus slender, length 0.80 × merus, with two robust setae; propodus slender, length 1.33 × carpus, anterior margin with a row of five robust setae; dactylus short, falcate.

Pereopod 6 (Fig. 8 C ), coxa similar but slightly smaller than coxa 5; basis elongate-ovate, length 1.91 × width, anterior margin with two plumose and three setae, posterior margin with row of unequal plumose setae; merus subrectangular, length 0.84 × basis, posterior margin with one robust and five simple setae, posterodistal corner with one long and two robust setae; carpus with three robust setae on posterior margin, posterodistal corner with one robust and three setae; propodus slender, length 1.79 × carpus, with a row of five robust setae anteriorly; dactylus falcate.

Pereopod 7 (Fig. 8 D ) similar to pereopod 6, but slightly longer, coxa small, weakly bilobate.

Uropod 1 (Fig. 8 E ), peduncle subrectangular, with two dorsolateral robust setae, ventrodistal end lacking inter-ramal process, length 1.27 × inner ramus; outer ramus with two dorsal and three terminal robust setae; inner ramus subequal to outer ramus, with three dorsal and four terminal robust setae.

Uropod 2 (Fig. 8 F ), peduncle short, subrectangular, subequal to inner ramus in length, with two dorsolateral and one dorsomedial robust setae; outer ramus with three dorsal and four terminal robust setae; inner ramus subequal to outer ramus, with two dorsal and three terminal robust setae.

Uropod 3 (Fig. 8 G ) uniramus, peduncle short, length 0.83 × ramus, unarmed; ramus biarticulate, proximal article with five setae, terminal article minute, with one long seta on apex.

Telson (Fig. 8 H ) entire, short, broader than long, truncate distally, each lobe with two subapical setae and 1–2 unequal robust setae on the apex.

Remarks.

Grandidierella naroensis sp. nov. is morphologically similar to G. pseudosakaensis Ariyama, 2020 , G. osakaensis Ariyama, 1996 , and G. fasciata Ariyama, 1996 in the following characters and character states: 1) gnathopod 1, merus with a small posterodistal notch; 2) gnathopod 1, carpus with three processes posterodistally. However, G. naroensis sp. nov. is distinguished from its congeners by the characters and character states listed in Table 2 and the following features (different characteristics of G. pseudosakaensis , G. osakaensis , and G. fasciata in brackets): 1) maxilla 1, outer plate with eight teeth (vs with nine teeth in G. pseudosakaensis and with 10 teeth in G. fasciata ); 2) gnathopod 1, ischium without a posterodistal process (vs with a process in G. osakaensis ); 3) gnathopod 1, carpus with small distal and proximal processes and a large middle process (vs with large middle and proximal processes and a small distal process in G. pseudosakaensis , G. osakaensis , and G. fasciata ); 4) gnathopod 1, propodus subovate (vs subrectangular in G. pseudosakaensis , G. osakaensis , and G. fasciata ); 5) gnathopod 2, posterior margin of propodus with 3 robust setae (vs with 5 robust setae in G. pseudosakaensis and G. osakaensis and with 4 robust setae in G. fasciata ); 6) pereopod 7, basis anterior margin without plumose setae (vs with plumose setae in G. pseudosakaensis , G. osakaensis , and G. fasciata ), and 7) uropod 1, peduncle without an inter-ramal process (vs with an inter-ramal process in G. fasciata ).

Etymology.

The species name is derived from the type locality, Narodo Island, located on the south coast of Korea.

Distribution.

Korea (Narodo Island).

Figures

Figure 2. Aoroides gracilicrus sp. nov. A male, 3.3 mm B Grandidierella naroensis sp. nov., male, 4.9 mm. Scale bars: 1.0 mm (A, B).

Figure 6. Grandidierella naroensis sp. nov., holotype, male, 4.9 mm A habitus B antenna 1 C antenna 2 D upper lip E lower lip F right mandible G right mandible teeth H left mandible teeth I maxilla 1 J maxilliped K maxilla 2. Scale bars: 1.0 mm (A); 0.4 mm (B, C, F); 0.2 mm (D, E, I – K); 0.05 mm (G, H).

Figure 7. Grandidierella naroensis sp. nov., holotype, male, 4.9 mm A gnathopod 1 B gnathopod 2 C pereopod 3. Scale bars: 0.4 mm (A – C).

Figure 8. Grandidierella naroensis sp. nov., holotype, male, 4.9 mm A pereopod 4 B pereopod 5 C pereopod 6 D pereopod 7 E uropod 1 F uropod 2 G uropod 3 H telson. Scale bars: 0.2 mm (A – D); 0.1 mm (E – H).