Polyankylis bogilensis, Lee & Chang & Kim, 2022

Lee, Jimin, Chang, Cheon Young & Kim, Il-Hoi, 2022, Symbiotic copepods (Cyclopoida and Siphonostomatoida) collected by light trap from Korea, ZooKeys 1115, pp. 1-71 : 1

Polyankylis bogilensis sp. nov.

Figs 18 , 19

Material examined.

Holotype ♀ (MABIK CR00250129) dissected and mounted on a slide, Site 22 (Yesong, Bogil Island, south coast, 34°08'11"N, 126°33'49"E), 31 May 2021, leg. J. Lee.

Description.

Female. Body (Fig. 18A ) dorsoventrally flattened. Body length 1.10 mm. Prosome 1.54 × longer than wide (570 × 370 μm). Cephalothorax with faint dorsal suture line between cephalosome and first pedigerous somite, with rounded posterolateral corners. Second to fourth pedigerous somites with rounded anterolateral and posterolateral corners. Urosome (Fig. 18B ) six-segmented. Fifth pedigerous somite 155 μm wide, slightly wider than genital double-somite. Genital double-somite 1.15 × longer than wide (170 × 148 μm), widest at proximal third of double-somite; posterior two-thirds gradually narrowing posteriorly; genital apertures positioned dorsolaterally at widest region of double-somite. Three free abdominal somites 70 × 93 μm, 56 × 86 μm, and 90 × 90 μm, respectively. All urosomal somites smooth, unornamented. Caudal rami straight backwards, rectangular, isolated from each other; each ramus (Fig. 18C ) 2.96 × longer than wide (80 × 27 μm), armed with six setae (seta II-VII); seta II positioned dorsally at 45% region of ramus length; seta V much longer than other caudal setae; seta III feebly pinnate, other five setae naked.

Rostrum (Fig. 18A, D ) as broad, spatulate anterior prominence of cephalothorax. Antennule (Fig. 18E ) 295 μm long, six-segmented, gradually narrowed distally; armature formula 2, 7, 6 (or 2. 6, 7), 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna (Fig. 18F ) four-segmented; first segment (coxobasis) with one seta at inner distal corner; second segment (first endopodal segment) longest, armed with one seta on inner margin and ornamented with setules on outer margin; short third segment with one small claw and two very unequal setae; terminal segment 1.28 × longer than wide (23 × 18 μm), distally armed with three claws of different lengths and three unequal setae, including minute outermost seta, and ornamented with minute spinules on subdistal outer margin.

Labrum (Fig. 18G ) bilobed, with deep median incision and proximal sclerotization band; each lobe distinctly longer than wide (~ 41 × 25 μm), divided from proximal part by weak suture line, with uneven outer margin. Mandible (Fig. 18H ) with two very unequal outer scales (spiniform proximal one and large, plate-like distal one) followed by stout tubercle; inner margin short, with circular row of spinules at junction between distal lash and inner margin; distal lash short, denticulate along outer margin, with fine denticle along inner margin; terminal part of lash not flexible. Maxillule (Fig. 18I ) lobate, armed with four setae; larger distal three setae pectinate along their inner margin; smaller inner margin seta naked, not articulated at base. Maxilla (Fig. 18J ) two-segmented; proximal segment (syncoxa) broad, with one claw-like cusp on proximal part of posterior surface; distal segment (basis) armed with two spiniform setae (setae I and II), terminating in short, spiniform distal lash bearing four spines followed by one or two denticles along outer margin; seta I (inner seta) large, spinulose, proximal six spinules markedly larger than other spinules on seta; seta II (anterior seta) distally unequally bifurcate, with row of spinules, proximal four or five of these spinules much larger than distal spinules. Maxilliped (Fig. 19A ) three-segmented; first segment (syncoxa) unarmed; second segment (basis) broadened, armed with two large setae distantly isolated from each other: proximal seta spiniform, curved, extending to distal tip of maxilliped, ornamented with three kinds of spinules, eight extremely long spinules on proximal part of inner margin followed distally by minute spinules and row of several small spinules along outer margin; distal seta straight, less than half as long as proximal seta, feebly spinulose along both margins; terminal segment (endopod) distally forming spinulose claw, proximally with one spine, one dentiform process and one small seta.

Leg 1-3 (Fig. 19B-D ) biramous, each with three-segmented exopod and two-segmented endopod; coxa with minute spinules at outer distal corner and large, pinnate inner seta; outer seta on basis naked. Leg 3 dissimilar to leg 2 in having three inner setae (instead of four) on distal endopodal segment. Leg 4 (Fig. 19E ) uniramous, with distinctly two-segmented exopod; endopod absent; coxa lacking inner seta; spines on exopod elongate. Armature formula for legs 1-4 as follows:

Leg 5 (Fig. 19F ) consisting of one dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment 1.72 × longer than wide (31 × 18 μm) armed with one spine (45 μm long) one naked seta (91 μm long). Leg 6 unarmed (Fig. 19F ).

Male. Unknown.

Etymology.

The name of the new species is taken from the type locality, Bogil Island.

Remarks.

The genus Polyankylis currently consists of three known species: P. orientalis Ho & Kim, 1997, P. australis Karanovic, 2008, and P. ovilaxa . Polyankylis australis is known from Australia ( Karanovic 2008) and the other two from Korea ( Ho and Kim 1997; Kim 2014). These three species are distinguished from P. bogilensis sp. nov. by different features, as follows: P. orientalis has a claw-like distal process on the coxobasis of the antenna (cf. this process absent in P. bogilensis sp. nov.) and a single-segmented exopod of leg 4 (cf. two-segmented in P. bogilensis sp. nov.); P. australis has an aesthetasc on the second endopodal segment of the antenna (cf. this aesthetasc absent in P. bogilensis sp. nov.), the terminal antennal segment is 3.5 × longer than wide (cf. 1.28 × longer than wide in P. bogilensis sp. nov.), and the maxillary syncoxa lacks a claw-like process (cf. this process present in P. bogilensis sp. nov.); and P. ovilaxa has caudal rami which are 4.40 × longer than wide (cf. 2.96 × in P. bogilensis sp. nov.), the terminal antennal segment is 2.5 × longer than wide, and the maxillary syncoxa lacks the claw-like process.

Figures

Figure 18. Polyankylis bogilensis sp. nov., female A habitus, dorsal B urosome, dorsal C left caudal ramus, dorsal D rostrum E antennule F antenna G labrum H mandible I maxillule J maxilla. Scale bars: 0.2 mm (A); 0.1 mm (B); 0.02 mm (C, F-J); 0.05 mm (D, E).

Figure 19. Polyankylis bogilensis sp. nov., female A maxilliped B leg 1 C leg 2 D endopod of leg 3 E leg 4 F leg 5 and genital aperture, dorsal. Scale bars: 0.02 mm.