Nannastacus leeae, Lee, Chang-Mok, Kim, Sung-Hyun & Kim, Young-Hyo, 2017

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 : 560-566

Nannastacus leeae sp. nov.

( Figs. 4–7 )

Type material. Holotype, adult male, 2.1 mm, cat no. NIBRIV0000299462, Nohwa Island, Nohwa-eup, Wandogun , Jeollanam-do., 34° 13′ 24″N, 126° 34′ 28″E, 23 May 1998, (C.M. Lee) collected with light trap . Paratypes, 1 adult ♂, data same as holotype, and the remaining paratypes 9 ♂ (including 2 dissected males), cat. No. DKUCUM 201701, in the Dankook University.

Additional material examined: 3♂, Port Jeongja, Jeongja-dong , Ulsan., 35° 37′ 03″N, 126° 27′ 00″E, 4 Nov. 1994, (C.M. Lee) by light trap ; 2♂, Port Wando, Gunnae-ri, Wando-eup , Wando-gun , Jeollanam-do., 34° 19′ 05″N, 126° 45′ 50″E, 20 May 1998, (C.M. Lee) by light trap ; 9♂, Namchang bridge, Namchang-ri, Bukpyeong-myeon , Haenam-gun , Jeollanam-do., 34° 24′ 07″N, 126° 37′ 41″E, 20 May 1998, (C.M. Lee) by light trap ; 2♂, Maemuldo Island, Hansan-myoen, Tongyeong-si , Gyeongsangnam-do., 34° 38′ 51″N, 128° 34′ 30″E, 28 June 2002, (Y.H. Kim) by light trap.

Etymology. The specific name leeae is in honor of Dr. Kyung-Sook Lee, who has contributed to knowledge of Korean Amphipoda and Cumacea .

Diagnosis. Carapace covered with numerous minute granules and ornamented with several symmetrical rows of large spatulate tubercles, pereonites 2, 3 with 1 pairs of blunt spines on dorsal surface, fourth and fifth pereonites with several blunt spines on dorsal surface. All pleonites with several strong spines on dorsal surface, uropodal peduncle very short, 0.35 times as long as telsonic somite.

Description. Holotype adult male, 2.1 mm, cat no. NIBRIV0000299462.

Body ( Fig. 4 ) about 2.1 mm long, excluding uropods; surface covered with numerous minute granules and ornamented with several symmetrical rows of large spatulate tubercles. Paratype adult male, 2.1 mm. Carapace ( Fig. 5 A, B) subequal to 1/3 of body length, 1.42 times as long as its width, 1.54 times as long as its depth; width slightly longer than depth; shape nearly rectangular in dorsal view, dorso-median portion raised, with several spatulate tubercles, both dorso-lateral sides with characteristic rounded humps. Antennal notch ( Fig. 5 A, B) deeply concaved; antero-lateral margin serrated, with row of strong spines along antro-lateral margin. Ocular lobe ( Fig. 5 B) very broad, composed of 2 eyes having 3 lenses each.

Pereon ( Fig. 5 A, B) 0.61 times as long as carapace, nearly 1/5 length of body. Second and third pereonites with 1 pairs of blunt spines on dorsal surfaces; fourth and fifth pereonites with several blunt spines on dorsal surfaces. Pleon ( Fig. 5 A) 0.85 times as long as cephalothorax; all pleonites with several strong spines on dorsal surfaces; pleotelson ( Fig. 4 F) with 2 rows of spines on dorsal surface, and 2 terminal setae.

Antenna 1 ( Fig. 5 C) peduncle composed of 3 articles; article 1 subequal to remaining articles combined, with 5 simple setae on outer distal corner; article 2 0.45 times as long as first article, with 2 simple setae on outer margin; inner corner inflated, with 2 complex pedunculated setae; article 3 slightly shorter than article 2, with 1 complex pedunculated seta on distal margin; main flagellum composed of 3 articles, slightly longer than peduncular article 3; article 3 with 2 simple setae and 2 aesthetascs on terminal margin; accessory flagellum 1-articulated, with 4 simple setae.

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

Labium ( Fig. 6 A) with 2 stout flattened setae apically, with hair-like setae on medial margin.

Left mandible ( Fig. 6 B) with row of 4 lifting setae between lacinia mobilis and pars molaris; incisor with 4 teeth; lacinia mobilis with 3 teeth.

Right mandible ( Fig. 6 C) similar to left, with row of 4 lifting setae; incisor with 4 teeth.

Maxilla 1 ( Fig. 6 D) outer endite broad, with a row of 12 stout simple setae terminally, lateral and medial margins with few hair-like setae; inner endite with 1 simple, 2 microserrate, and 1 plumose setae terminally.

Maxilla 2 ( Fig. 6 E) broad endite with 9 simple and 2 bifid simple setae terminally, near medial portion with oblique row of 13 simple and hair-like setae; outer and inner endites with simple setae terminally.

Maxilliped 1 ( Fig. 6 F) basis medial lobe with 4 simple, 2 hook, 1 serrate, few hair-like setae medially, 1 stout knob-like and 5 simple setae distally, few long hair-like setae laterally; carpus with 10 serrate setae medially, hairlike setae laterally; propodus with 1 long plumose and 2 simple setae distally, hair-like setae laterally; dactylus with 5 simple setae terminally.

Maxilliped 2 ( Fig. 6 G) basis with 1 plumose seta on medial distal corner, hair-like setae medially, 1 simple seta and hyaline flattened teeth laterally; merus with hair-like setae laterally; carpus with 4 plumose and hair-like setae medially, hair-like setae laterally; propodus with 1 plumose, 2 microserrate, and 1 simple setae medially, hair-like setae laterally; dactylus with stout terminal seta.

Maxilliped 3 ( Fig. 6 H) basis slightly longer than remaining articles combined, with numerous hair-like and 2 plumose setae posteriorly; outer corner very inflated, with 1 short simple, 2 long plumose setae, and hyaline flattened teeth; ischium with 1 plumose seta and hyaline flattened teeth posteriorly; merus with 1 plumose seta and hyaline flattened teeth posteriorly, 1 long plumose seta and 1 strong hyaline flattened tooth on outer corner; carpus with 1 plumose, numerous hair-like setae, and hyaline flattened teeth posteriorly, 1 long plumose seta on outer margin; propodus with 3 plumose, 1 simple, and hair-like setae; dactylus with 2 serrate and 3 simple setae terminally.

Pereopod 1 ( Fig. 7 A) basis 0.66 times as long as remaining articles combined, with row of hyaline flattened teeth anteriorly; ischium and merus with 1 strong hyaline flattened tooth anteriorly respectively, ischium with row of hyaline flattened teeth posteriorly; carpus 1.92 times as long as merus; propodus 0.76 times as long as carpus, with 1 small pappose and few hair-like setae posteriorly; dactylus 0.85 times as long as propodus, with 1 short pappose, 3 simple, and 1 stout setae.

Pereopod 2 ( Fig. 7 B) basis 1.21 times as long as remaining articles combined, with 2 rows of hyaline flattened teeth anteriorly, serrated posterodistally; merus with row of hyaline flattened teeth posteriorly; carpus 1.75 times as long as merus; propodus 0.53 times as long as carpus, with hair-like setae posteriorly; dactylus 2.16 times as long as propodus, with hair-like and 6 simple setae.

Pereopod 3 ( Fig. 7 C) basis 0.75 times as long as remaining articles combined; merus 1.25 times as long as ischium; carpus 2.60 times as long as merus; propodus 0.77 times as long as carpus; dactylus fused with its terminal stout seta.

Pereopod 4 ( Fig. 7 D) basis 0.61 times as long as remaining articles combined; merus subequal to ischium; carpus 3.12 times as long as merus; propodus 0.38 times as long as carpus; dactylus fused with its terminal stout seta.

Pereopod 5 ( Fig. 7 E) basis slender, 0.34 times as long as remaining articles combined; merus 1.29 times as long as ischium; carpus 3.33 times as long as merus; propodus 0.69 times as long as carpus; dactylus fused with its terminal stout seta.

Uropod ( Fig. 7 F) peduncle very short, 0.66 times as long as last pleonite, with row of serrations on dorsal surface, endopod 1-articulate, 5.25 times as long as peduncle, inner margin strongly serrated, terminal margin with 2 short and 1 long microserrate setae; exopod composed of 2 articles, approximately 1/4 of endopod length, article 2 with 2 short setae and 1 long terminal seta.

Remarks. This new species resembles Nannastacus inconstans Hale, 1945 , N. nyctagineus Gamô, 1962 , and N. pectinatus Gamô, 1962 in having numerous minute granules and some spatuliform/spiniform tubercles on dorsal surfaces of pereon and pleon. However, the new species is easily distinguished from others by the following combination of features (based on list in Table 1): 1) carapace covered with numerous minute granules and several rows of large spatulate tubercles (vs. large granules and squamose-reticulate in N. inconstans ; numerous minute granules in N. nyctagineus ; minute spiniform granules in N. pectinatus ); 2) carapace shape is nearly rectangular in dorsal view (vs. nearly ovate in N. inconstans , N. pectinatus ); 3) antenna 2 not extending beyondpleonite 6 (vs. extending beyondpleonite 6 in N. nyctagineus ); 4) pereonites 2 and 3 with a pair of blunt tubercles, pereonites 4 and 5 with several strong spines (vs. strongly tuberculate, almost spiniform in N. inconstans ; 1–2 pairs of teeth in N. nyctagineus ; a pair of spines and spiniform tubercles in N. pectinatus ); 5) uropodal peduncle length, about 2/3 of pleotelson (vs. less than 2/ 3 in N. inconstans ; about 5/ 6 in N. nyctagineus ; 2/ 3 in N. pectinatus ); and 6) uropodal exopod length, about 1/4 of endopod (vs. about 1/ 3 in N. inconstans ; about 1/ 13 in N. nyctagineus ; about 1/ 2 in N. pectinatus ); 7) uropodal endopod inner margin, serrate (vs. serrate, with 5–6 small stout setae in N. nyctagineus ).

Distribution. Korea (South Sea, shallow water, depth 5m).

Figures

FIGURE 4. Nannastacus leeae sp. nov. holotype, adult male, 2.1 mm, cat no. NIBRIV 0000299462. Scale bar = 0.3 mm.

FIGURE 5. Nannastacus leeae sp. nov. paratype, adult male, 2.1 mm: A, habitus, lateral; B, cephalothorax, dorsal; C, antenna 1; D, antenna 2. Scale bars = 0.3 mm (A, B), 0.1 mm (C, D).

FIGURE 6. Nannastacus leeae sp. nov. paratype, adult male, 2.1 mm: A, labium; B, left mandible; C, right mandible; D, maxilla 1; E, maxilla 2; F, maxilliped 1; G, maxilliped 2; H, maxilliped 3. Scale bars = 0.2 mm (H), 0.1 mm (A – G).

FIGURE 7. Nannastacus leeae sp. nov. paratype, adult male, 2.1 mm: A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pleotelson and uropod. Scale bars = 0.2 mm (A – F).