Melita nagatai Yamato 1987
Creators: name: Kim, Kyung-Won
name: Zhang, Xin
name: Choi, Jae-Hong
name: Kim, Jun
name: Kim, So-Yeon Shin and Young-Hyo
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Melitidae
Melita
Melita nagatai

description: 58. Melita nagatai Yamato, 1987
나P네AEėḁNƞầNjạ (ṵAE)* (Figs. 4, 5, 13B)
Melita nagagai Yamato, 1987: 289, Figs. 11 - 15; Tomikawa et al., 2018: 74.
Material examined. 5 inds., Chuja Bridge, 27 August 2021.
Description. Male (MABIK CR00252864): Body (Fig. 4A) 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) ventral margin smooth, unarmed, pleonites 3 ventral margin with 4 stout setae; pleonites 1 - 3 with small cusps posteroventrally.
Antenna 1 (Fig. 4C) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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.
description: Published as part of 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, pp. 1-26 in Journal of Species Research 12 (1) on pages 11-13, DOI: 10.12651/JSR.2023.12.1.001, http://zenodo.org/record/8120103