Leptopsyllus (Leptopsyllus) koreanus sp. n. Figs 5, 6, 7, 8

Type locality.

Republic of Korea, Maemul Island (Korean name: Maemuldo), subtidal zone off 37° 37'43.38"N, 128° 46'24.51"E (depth: 50 m, muddy sand).

Material examined.

Holotype 1♂ (MABIK CR00235288) dissected on four slides. Sampled by a grab on a fishing boat on 23 Feb 2011.

Diagnosis.

Description of female. Unknown.

Description of male. Total body length 575 µm; largest width measured at posterior margin of cephalic shield: 105 µm (Fig. 5A); body cylindrical and slightly depressed dorsoventrally; urosome gradually tapering posteriorly; sensilla present as illustrated in Fig. 5 A–C; body somites connected by well-developed arthrodial membranes. Rostrum small, fused with cephalic shield; with 2 sensilla (Fig. 5D). Cephalothorax (Fig. 5A, B) bell-shaped, smooth posterior margin, with few sensilla; pleural areas weakly developed and posterolateral angles rounded; posterior margin smooth, without distinct hyaline frill. Anal somite (Figs 5A, 6A1) with developed spinulose operculum.

CR (Fig. 6A1, A2). Parallel, about 3.1-times as long as greatest width, conical, distal margin rounded; each ramus armed with 7 setae; seta I bare, situated rather ventrally; setae II and III bare, situated laterally; seta IV shortest, bare; seta V longest, about 3 times as long as the caudal ramus; seta VI bare, composite, consisting of proximal process and distal seta; setae IV–VI displaced onto dorsal surface of ramus; seta VII tri-articulate at base and arising from inner dorsal surface.

A1 (Fig. 6B1-B5) 7-segmented, short, robust, subchirocer; seg-1 with row of spinules along sub-distal margin; seg-5 swollen; armature formula: 1-[1 bare], 2-[9 bare + 1 pinnate], 3-[7 bare + 1 pinnate], 4-[2 bare], 5-[9 bare + 2 pinnate + (1 + ae)], 6-[2 bare], 7-[12 bare + 1 pinnate]; visible apical acrothek not present.

A2 (Fig. 6C1, C2) 4-segmented, comprising coxa, basis, 2-segmented enp, and 1-segmented exp; coxa small and bare; basis approximately 3.1-times as long as maximum width, ornamented with row of spinules along inner margin; exp inner distal corner forming spinous projection with 2 lateral and 2 distal naked setae; proximal endopodal segment with 1 pinnate abexopodal seta; distal endopodal segment ornamented with 2 rows of spinules horizontally, with 2 spine-like setae, 1 pinnate seta sub-apically (Fig. 6C2), 4 geniculate setae around distal margin, and 1 longest geniculate seta fused at base with 1 longest seta.

Mandible (Fig. 7A1, A2). Coxa with well-developed gnathobase bearing 1 bare seta at the dorsal corner and 6 overlapping teeth; palp biramous, comprising basis, 1-segmented exp and enp; basis with 1 pinnate seta and ornamented with row of spinules near base of seta; exp small, with 2 bare setae; enp long with 2 lateral setae in middle and 5 basally fused setae at apex.

Maxillule (Fig. 7B). Praecoxal arthrite well-developed, with 7 spines, 1 pinnate seta, and 2 juxtaposed slender setae on anterior surface; coxa with cylindrical endite bearing 1 claw and 2 naked setae; basis cylindrical; endites fused, with 5 naked setae; exp 1-segmented, small, with 2 pinnate setae; enp 1-segmented, elongate, rectangular, with 6 naked setae around apex.

Maxilla (Fig. 7C). Syncoxa with 3 endites; praecoxal endite with 1 pinnate and 1 naked setae; proximal and distal coxal endite with 3 naked setae; allobasis with 1 uni-pinnate strong claw, 1 bare claw, 1 accessory seta, and 1 bare seta near base of enp; enp 2-segmented; enp-1 with 2 bare setae; enp-2 with 3 bare setae apically.

Maxilliped (Fig. 7D) 3-segmented, comprising syncoxa, basis and 1-segmented endopod; syncoxa with 1 bare seta; elongate basis ornamented with 3 spinules in middle; enp 2.5 times as long as wide, with 2 naked seta laterally, 1 apical seta, 1 curved stout claw, and 1 accessory on claw.

P1 (Fig. 8A). Basis without outer seta, with 1 bare seta on proximal inner margin; exp shorter than enp; exp-1 with 1 long uni-pinnate seta near outer distal corner, ornamented with row of spinules along outer margin and with long spinules on inner margin; exp-2 with 4 long uni-pinnate setae; enp-1 elongate and approximately 3.5 times as long as enp-2 and ornamented with row of spinules along outer margin; enp-2 small, with 1 geniculate seta.

P2, P3 (Fig. 8B, C). Coxa ornamented with rows of spinules as figured; basis with 1 outer bare seta and ornamented with row of spinules on inner and outer margin; exp 3-segmented; exp-1 longest, with 1 outer uni-pinnate spine; exp-2 shortest, with 1 outer uni-pinnate spine; exp-3 sub-rectangular, with 2 pinnate spines; enp absent.

P4 (Fig. 8D). Coxa ornamented with 2 rows of spinules; basis with 1 outer seta; exp 3-segmented; exp-1 and -2, with 1 outer uni-pinnate spine; exp-3 with 2 uni-pinnate spines; enp represented by elongate segment with 1 spine-like seta.

Armature formula as follows:

P5 (Fig. 5C). Exopod and baseoendopod not fused; baseoendopod with 1 outer basal seta, endopodal lobes confluent with 1 seta each; exp small, triangular, with 3 naked setae.

P6 (Fig. 5C) symmetrical, with 2 bare setae arising from small protrusion on inner part of P6, and 1 outer longest bare seta.

Etymology.

The specific name refers to the type locality of the new species in Korea.