Pusanomyicola sensitivus gen. nov. sp. nov.

Figs 16, 17

Material examined.

Holotype ♂ (MABIK CR00250128) dissected and mounted on a slide, Site 11 (Yeongdo, Pusan, 35°04'31.0"N, 129° 05'08.7"E), 07 Jul. 2020, leg. J. G. Kim.

Description.

Male. Body (Fig. 16A) narrow, clearly segmented, gradually narrowed from anterior to posterior. Body length 2.06 mm. Maximum width 400 μm across cephalosome. Prosome 886 μm long, distinctly shorter than urosome, consisting of cephalosome and four pedigerous somites. All prosomal somites with rounded lateral margin. Urosome six-segmented. Fifth pedigerous somite short, narrower than genital somite. Genital somite nearly rectangular, 1.2 × longer than wide (273 × 227 μm); genital operculum (Fig. 17H) distinct, bearing three setae and row of scale-like spinules along inner distal margin. Four abdominal somites 177 × 159 μm, 150 × 127 μm, 100 × 109 μm, and 132 × 95 μm, respectively. Caudal ramus (Fig. 16B) slender, 7.9 × longer than wide (284 × 36 μm), armed with seven setae (seta I to VII), ornamented with many transverse rows of minute spinules; setae I and II positioned at same place at 23% length of ramus on outer margin; setae III-VI positioned on distal margin; seta VII positioned on dorsal surface at 38% length of ramus; all caudal setae naked, short, longest one (seta V) one-third as long as ramus.

Rostrum not developed. Antennule (Fig. 16C) 245 μm long, seven-segmented, densely armed with setae and aesthetascs; armature formula 4+7 aesthetascs, 15+15 aesthetascs, 4+2 aesthetascs, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; all setae naked, mostly short; aesthetascs shorter than antennule. Antenna (Fig. 16D) three-segmented, consisting of coxobasis and two-segmented endopod; coxobasis as long as wide, with one short seta at inner distal corner; first endopodal segment ~ 1.5 × longer than wide, with one small seta at inner subdistal region; second endopodal segment twice longer than wide, terminated in strong claw, armed with five small setae (one on inner margin, one on subdistal outer margin, and three at inner distal corner, one of latter truncate), and ornamented with scattered scale-like spinules on outer surface; terminal claw half as long as second endopodal segment.

Labrum (Fig. 16E) much wider than long, with patch of several blunt spinules on each lateral surface; posteromedian incision shallow, semicircular, with finely spinulose margin. Mandible (Fig. 16F) narrowed distally, armed with three armature elements distally: short outer element not articulated at base, with five large teeth along outer margin and five denticles distally; longest middle element (stiff lash) straight, not articulated at base, with several denticles at distal part; slender inner element (spiniform seta) articulated at base, as long as middle element, denticulate distally. Maxillule (Fig. 16G) as digitiform lobe tipped with two unequal, naked setae. Maxilla (Fig. 17A) as tapering, unsegmented lobe bearing patch of spinules on posteroventral surface, tipped with one naked seta. Maxilliped (Fig. 17B) four-segmented; first segment (syncoxa) broader than long, unarmed; second segment (basis) rectangular, armed with one broad, leaf-like seta subdistally and one small seta distally; short third segment (first endopodal segment) unarmed; terminal segment (second endopodal segment) tapering, curved, trifurcate at tip, with one small seta on inner margin; claw or hook absent (or reduced to small middle process of distal tip).

Legs 1-4 (Fig. 17C-F) biramous, with three-segmented rami; inner coxal seta small, naked; outer seta on basis also small, naked; both rami of each leg almost equal in length; spines on exopods and endopods spinulose along both margins. Leg 1 lacking inner distal element of basis, but with three blunt dentiform spinules near base of endopod. Legs 3 and 4 with same armature on third exopodal segment. Armature formula for legs 1-4 as follows:

Leg 5 (Fig. 17G) small, consisting of protopod and exopod; protopod articulated from somite, as long as wide, with one seta dorsodistally; exopod 3.0 × longer than wide (45 × 15 μm), armed with three naked setae (two on distal margin and one at 75% region of dorsal margin), ornamented with few spinules ventrodistally; setae on protopod and exopod shorter than exopodal segment. Leg 6 (Fig. 17H) represented by three naked setae on inner distal margin of genital operculum.

Female. Unknown.

Etymology.

The specific name Pusanomyicola sensitivus refers to the presence of the multiple aesthetascs on the male antennule.