Nannastacus spinulosus Gamô, 1962

Lee, Chang-Mok, Kim, Sung-Hyun & Kim, Young-Hyo, 2017, A new species and new record of the genus Nannastacus (Crustacea: Cumacea: Nannastacidae) from Korea, Zootaxa 4282 (3), pp. 556-566 : 557-560

Nannastacus spinulosus Gamô, 1962 .

( Figs. 1–3 )

Nannastacus spinulosus Gamô, 1962 , p. 183, figs. 22, 23; 1963, p. 86; 1967, p. 250; 1968, p. 192, fig. 5.

Material examined: 14 ♂, Port Chunjin, Udo Island , Udo-myeon , Jeju-si , Jeju-do Island., 33° 29′ 31″N, 126° 57′ 00″E, 21 July. 2013, (S.H. Kim), collected with light trap.

Type locality. Japan.

Description. Adult male, 1.9 mm, cat no. NIBRIV0000416868.

Body ( Fig. 2 A, B) about 1.9 mm long, excluding uropods. Carapace ( Fig. 2 A, B) subequal to 1/3 length of body, 1.28 times as long as its width, 1.63 times as long as its depth; shape nearly ovate in dorsal view; surface with short plumose setae, numerous spinules and spines. Antennal notch ( Fig. 2 A) deeply concaved. Ocular lobe ( Fig. 2 B) very broad, composed of 2 eyes having 3 lenses each. Pereon ( Fig. 2 A, B) 0.48 times as long as carapace, nearly 1/5 length of body; first pereonite partially fused with carapace; second to fifth pereonites with short plumose setae, spinules, and spines. Pleon ( Fig. 2 A) 0.81 times as long as cephalothorax; all segments with spinules and strong spines on dorsal surfaces; serrated groove for antenna 2 well developed.

Antenna 1 ( Fig. 2 C) peduncle composed of 3 articles; article 1 subequal to remaining articles combined, with 3 annulate and hair-like setae on outer distal corner; article 2 0.43 times as long as article 1, with 2 annulate setae on outer distal corner, inner corner with 3 complex pedunculated setae; article 3 subequal to article 2, with 3 complex pedunculated setae on distal margin; main flagellum composed of 2 articles, article 2 with 2 long aesthetascs apically; accessory flagellum 1-articulate, with 4 simple and 1 complex pedunculated setae.

Antenna 2 ( Fig. 2 D) not extending beyond pleonite 6; peduncle 5-articulate, articles 4–5 with numerous simple setae; article 5 elongate, with 2 complex pedunculated setae distally.

Maxilliped 3 ( Fig. 2 E) basis slightly longer than remaining articles combined, with hair-like setae anteriorly, row of hyaline flattened teeth and hair-like setae posteriorly, 3 plumose setae posterodistally; outer corner very inflated, reaching to about 1/2 length of merus, with 2 long plumose and hair-like setae, and hyaline flattened teeth; ischium with hair-like setae posteriorly; merus with 1 simple and 1 plumose setae, and hyaline flattened teeth posteriorly; carpus with row of hyaline flattened teeth anteriorly, 2 simple and 1 plumose setae, and hyaline flattened teeth posteriorly; propodus with hair-like, 2 plumose, and 2 simple setae; dactylus with 2 microserrate and 3 simple setae terminally.

Pereopod 1 ( Fig. 3 A) basis 0.69 times as long as remaining articles combined, with row of hyaline flattened teeth and 1 simple seta anteriorly, hair-like setae posteriorly, row of hyaline flattened teeth and 2 short simple setae posterodistally; ischium with 2 hyaline flattened teeth anteriorly, row of hyaline flattened teeth, 1 simple and hairlike setae posteriorly; merus 2.13 times as long as ischium, with 1 simple seta and 2 small hyaline flattened teeth anteriorly, 2 hyaline flattened teeth, 1 simple and hair-like setae posteriorly; carpus 1.89 times as long as merus, with 2 simple setae anteriorly, 2 simple setae posteriorly; propodus 1.12 times as long as carpus, with 4 simple and hair-like setae; dactylus 0.57 times as long as propodus, with 5 hyaline flattened teeth anteriorly, row of short hairlike setae posteriorly, 2 short simple setae distally, 2 simple and 1 stout setae terminally.

Pereopod 2 ( Fig. 3 B) basis 1.21 times as long as remaining articles combined, with 2 rows of hyaline flattened teeth anteriorly; merus 4.10 times as long as ischium, with 3 simple setae; carpus 2.44 times as long as merus, with 2 simple setae anteriorly, 2 simple setae posterodistally; propodus 0.25 times as long as carpus; dactylus 3.80 times as long as propodus, with 2 simple setae anteriorly, 1 simple and hair-like setae posteriorly, 5 simple setae terminally.

Pereopod 3 ( Fig. 3 C) basis 0.75 times as long as remaining articles combined; merus subequal to ischium; carpus 2.88 times as long as merus; propodus 0.73 times as long as carpus; dactylus fused with its terminal stout seta.

Pereopod 4 ( Fig. 3 D) basis 0.55 times as long as remaining articles combined; merus subequal to ischium; carpus 4.13 times as long as merus; propodus 0.64 times as long as carpus; dactylus fused with its terminal stout seta.

Pereopod 5 ( Fig. 3 E) basis slender, subcylindrical, 0.33 times as long as remaining articles combined; merus 1.25 times as long as ischium; carpus 4.18 times as long as merus; propodus 0.53 times as long as carpus; dactylus fused with its terminal stout seta.

Uropod ( Fig. 3 F) peduncle very short, 0.61 times as long as pleotelson, with several spines and 2 simple setae respectively; endopod 1-articulate, 3.36 times as long as peduncle; inner margin strongly serrated, with 4–5 short simple setae on dorsal surface, 1 long microserrate and 2 short microserrate setae terminally; exopod 1-articulate, subequal in length to 1/3 of endopod; with 1 long microserrate and 2 short simple setae terminally.

Remarks. Nannastacus spinulosus Gamô, 1962 is morphologically characterized by having numerous spinules and spines on surface of the body including the carapace, pereon, and pleon. Our specimens are in good agreement with the original description given by Gamô (1962) as follows: 1) ornament patterns of spinules and spines on surface of the body; 2) relative length of segments in pereopod 1; 3) relative length ratio of uropod peduncle, exopod, endopod, and pleotelson. However, several minor differences are found between our specimens and the previous report by Gamô (1962) (original descriptions in parentheses): 1) carapace and pereon with short plumose setae (vs. without plumose setae); 2) carapace subequal to 1/3 length of body (vs. nearly 1/5); 3) pleon 0.84 times as long as cephalothorax (vs. 0.70 times) 4) maxilliped 3, basis with hair-like setae on each margin (vs. without hair-like setae). It is possible that Gamô overlooked these minor characteristics.

Distribution. Korea (Jeju-do Is., shallow water, depth 6m).

Figures

FIGURE 1. Nannastacus spinulosus Gamô, 1962, adult male, 1.6 mm. Scale bar = 0.2 mm.

FIGURE 2. Nannastacus spinulosus Gamô, 1962, adult male, 1.9 mm, cat no. NIBRIV 0000416868: A, habitus, lateral; B, cephalothorax, dorsal; C, antenna 1; D, antenna 2; E, maxilliped 3. Scale bars = 0.3 mm (A, B), 0.2 mm (E), 0.1 mm (C, D).

FIGURE 3. Nannastacus spinulosus Gamô, 1962, adult male, 1.9 mm, cat no. NIBRIV 0000416868: A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pleotelson and uropod. Scale bar = 0.2 mm.