Melita nagatai Yamato, 1987

Kim, Kyung-Won, Zhang, Xin, Choi, Jae-Hong, Kim, Jun & Kim, So-Yeon Shin and Young-Hyo, 2023, Amphipods (Crustacea: Malacostraca) fauna from Chujado Island in Korea, Journal of Species Research 12 (1), pp. 1-26 : 11-13

publication ID	https://doi.org/ 10.12651/JSR.2023.12.1.001
DOI	https://doi.org/10.5281/zenodo.8144078
persistent identifier	https://treatment.plazi.org/id/039387B1-FFFE-8A6F-4600-FED57437F8B0
treatment provided by	Felipe
scientific name	Melita nagatai Yamato, 1987
status

Treatment

58. Melita nagatai Yamato, 1987 View in CoL View at ENA

나P네AEėḁNƞầNjạ (ṵAE)* ( Figs. 4 View Fig , 5 View Fig , 13B View Fig )

Melita nagagai Yamato, 1987: 289 , Figs. 11 - 15 View Fig View Fig View Fig View Fig View Fig ; Tomikawa et al., 2018: 74.

Material examined. 5 inds., Chuja Bridge, 27 August 2021.

Description. Male (MABIK CR00252864): Body ( Fig. 4A View Fig ) smooth, 8.0 mm long. Head subequal to pereonites 1, 2 combined; rostrum not elongated; lateral cephalic lobe truncate; eye round, small.

Pleonites 1, 2 ( Fig. 4B View Fig ) ventral margin smooth, unarmed, pleonites 3 ventral margin with 4 stout setae; pleonites 1 - 3 with small cusps posteroventrally.

Antenna 1 ( Fig. 4C View Fig ) slender, about 0.7 times as long as body length; peduncular article 1 with 5 robust setae ventrally; length ratio of peduncular articles 1 - 3 = 1.00: 1.24: 0.63; accessory flagellum 3-articulate; flagellum 21-articulate, about 1.7 times as long as peduncle.

Antenna 2 ( Fig. 4D View Fig ) about 0.6 times as long as antenna 1, peduncular article 2 with short gland cone ventrodistally; length ratio of peduncular articles 2 - 5 = 1.00: 1.50: 4.90: 4.90; flagellum 7-articulates, about 0.6 times as long as peduncle.

Gnathopod 1 ( Fig. 4E View Fig ) coxa subquadrate, deeper than wide, with ventral setules; basis subrectangular, narrowing proximally, with simple setae distal half of anterior margin, 8 simple setae posteriorly; merus with pubescence posteriorly; carpus elongate, width 0.3 times length, slightly shorter than basis, with pubescence anterodistally; propodus subovate, triangular lobe pointed and produced anterodistally, palm transverse; dactylus broad, falcate.

Gnathopod 2 ( Fig. 4F View Fig ) coxa to ischium similar to those of gnathopod 1, but basis less setose; carpus subtriangular, setose ventrally; propodus massive, subrectangular, both margins with clusters of setae, medial portion with two lows of setae; palm oblique; dactylus falcate, curved inward; length ratio of articles 2 - 7 = 1.00: 0.40: 0.47: 0.62: 1.40: 0.64.

Pereopod 3 ( Fig. 4G View Fig ) coxa similar to that of gnathopod 2; basis curved anteriorly; merus subrectangular, slightly longer than carpus, with 3 robust setae on dorsal margin; carpus and propodus slender; dactylus short, falcate; length ratio of articles 2 - 7 = 1.00: 0.22: 0.62: 0.53: 0.44: 0.09.

Pereopod 4 ( Fig. 4H View Fig ) similar to pereopod 3, except coxa 4 more concave posteriorly and produced midposteriorly; length ratio of articles 2 - 7 = 1.00: 0.20: 0.44: 0.32: 0.37: 0.09.

Pereopod 5 ( Fig. 5A View Fig ) coxa bilobate, anterior lobe protruding roundly downward; basis subovate, anterior margin with robust setae, posterior margin weakly serrulate; merus broader than carpus and propodus, robust setae on both margins; carpus and propodus subrectangular, slender; length ratio of articles 2 - 7 = 1.00: 0.21: 0.72: 0.60: 0.78: 0.14.

Pereopod 6 ( Fig. 5B View Fig ) similar to pereopod 5, except coxa 6 broader than that of pereopod 5; length ratio of articles 2 - 7 = 1.00: 0.20: 0.63: 0.53: 0.65: 0.09.

Pereopod 7 ( Fig. 5C View Fig ) similar to pereopod 6, except coxa semicircular, unilobate; basis ovate, posterior margin smooth and rounded; length ratio of articles 2 - 7 = 1.00: 0.18: 0.63: 0.53: 0.82: 0.17.

Uropod 1 ( Fig. 5D View Fig ) peduncle longer than both rami with 9 dorsolateral, 4 dorsomedial, 1 ventrolateral, and 1 apicolateral robust setae; both rami subequal in length, with dorsal robust setae.

Uropod 2 ( Fig. 5E View Fig ) about 0.6 times as long as uropod 1; peduncle with 3 dorsomedial and 1 apicolateral robust setae; inner ramus slightly longer than outer ramus.

Uropod 3 ( Fig. 5F View Fig ) variramous; peduncle short, about 0.4 times as long as outer ramus; inner ramus short, scale-like with 2 robust setae distally; outer ramus elongate, slender, and uniarticulate.

Telson ( Fig. 5G View Fig ) completely cleft, narrowing distally, apically acute, with 2 groups of subapical robust setae in each lobe.

Remarks. Melita nagatai is similar to M. bingoensis Yamato, 1987 . However, M. nagatai is easily distinguished from M. bingoensis by lacking medial robust setae on propodus of gnathopod 1. This species is also very similar to M. koreana Stephenson, 1944 in possessing a similar body form, especially subquadrate propodus of gnathopod 2. However, M. nagatai is morphologically distinguished from M. koreana as follows: (1) gnathopod 1, propodus with acute triangular lobe anterodistally; (2) epimeral plates 1 - 3 slightly acute ventrodistally. The newly recorded species in Chujado Island, M. nagatai is well accorded with the original description given by Yamato (1987). However, these morphological characteristics does not seem clear to distinguish between the two species. Therefore, systematic molecular verification through sequencing is necessary in the future for accurate identification of these two morphologically similar species.

Distribution. Korea (Chujado Island), Japan.