Kelleria robusta, Kim, 2021

Kim, Jae-Sang Hong and Il-Hoi, 2021, Copepods of the family Kelleriidae (Crustacea, Copepoda, Cyclopoida) from tropical waters of the Asia-Pacific, Journal of Species Research 10 (4), pp. 364-386 : 380-382

Kelleria robusta n. sp. ( Figs. 11 , 12 )

Material examined. One female (holotype, MABIK CR00247453 ) from invertebrate washings, SCUBA depth 15-30 m, Bohol, Philippines, 4 April 2014, Jimin Lee. Holotype (dissected and mounted on a slide) has been deposited in the Marine Biodiversity Institute of Korea ( MABIK), Seocheon, Korea.

Female. Body ( Fig. 11A ) robust, relatively large. Body length 2.16 mm. Prosome expanded, 1.42 mm long, occupying 66% of body length. Cephalothorax globular, much wider than long (864 × 1,236 μm), with weak dorsal suture line delimiting cephalosome and first pedigerous somite. Second pedigerous somite with pointed posterolateral corners. Urosome ( Fig. 11B ) 5-segmented. Fifth pedigerous somite 414 μm wide, distinctly wider than genital double-somite. Genital double-somite wider than long (255× 335 μm), with broader anterior part and narrower, tapering posterior part; genital apertures positioning at anterior third. Three free abdominal somites 80 × 189, 51 × 182, and 113 × 195 μm, respectively. Caudal ramus ( Fig. 11C ) short, 1.72 times longer than wide (136 × 79 μm), slightly longer than anal somite, with strongly tapering distal margin bearing minute pore at distal apex, armed with 6 setae; outer seta (seta II) positioning at midlength of ramus; this and dorsal seta (seta VII) naked, other setae pinnate.

Rostrum ( Fig. 11D ) slightly wider than long, nearly semi-circular, but with weakly angular distal apex. Antennule ( Fig. 11E ) 523 μm long, 7-segmented; armature formula 4, 13, 6, 3, 4 + aesthetasc, 2 + aesthetasc, and 7 + aesthetasc; all setae naked, except 2 feebly pinnate larger setae on first segment. Antenna ( Fig. 11F ) consisting of coxobasis and 3-segmented endopod; armature formula 1, 1, 2 + claw, and 5 + 2 claws; terminal segment 2.62 times longer than wide (131 × 50 μm), gradually narrowing distally, its 2 distal claws strong, shorter than segment, 109 and 95 μm long, respectively.

Labrum ( Fig. 11G ) with divergent posterolateral lobes and broad posteromedian incision. Mandible ( Fig. 11H ) bearing short distal lash; gnathobase with group of 5 spinules of unequal lengths proximally on convex side, about 15 teeth along convex margin, about 15 spinules of various sizes along concave margin. Maxillule ( Fig. 11I ) as elongate lobe bearing 3 distal setae of unequal lengths and 1 short setiform process on inner margin. Maxilla ( Fig. 11J ) 2-segmented; proximal segment (syncoxa) large but unarmed; distal segment (basis) with spiniform inner seta (seta I) bearing 3-5 spinules along both margins, naked anterior seta (seta II), rudimentary proximal seta (seta III), short spiniform distal lash, 6 spines along distal margin arranged as 1 large, 2 small, 1 large, 1 small, and 1 large ones from proximal to distal. Maxilliped ( Fig. 12A ) 3-segmented; first segment (syncoxa) elongate, unarmed; second segment (basis) with 2 spiniform setae, proximal one naked, distal one shorter but thicker than proximal one, finely spinulose along both margins; third segment (basis) small, terminating in spiniform process, with 2 short spiniform setae and 1 minute setule.

Legs 1-4 ( Fig. 12B- E ) biramous. Legs 1-3 with 3-segmented rami. Leg 4 with 3-segmented exopod and 1-segmented endopod. Outer seta on basis pinnate in legs 1 and 4, but naked in legs 2 and 3. Inner coxal seta well-developed, pinnate in legs 1-3, but minute, naked in leg 4. Endopodal segment of leg 4 2.83 times longer than wide (130 × 46 μm) bearing 1 cusp on outer margin; 2 distal spines 115 (inner) and 52 μm (outer), respectively; inner seta not extending to distal margin of segment. Armature formula for legs 1-4 as in type species.

Leg 5 ( Fig. 11B ) consisting of 1 small pinnate dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment ( Fig. 12F ) 2.90 times longer than wide (142 × 49 μm), slightly broadened in proximal half, armed with 2 naked setae distally, ornamented with several minute spinules in distal half; 2 distal setae 150 and 100 μm long, respectively. Leg 6 ( Fig. 12G ) represented by 1 cusp, 1 small setae, and 1 lateral seta tipped on process in genital aperture.

Male. Unknown.

Etymology. The name of the new species refers to its robust form of the body.

Remarks. As diagnostic features in the female of Kelleria robusta n. sp., (1) the genital double-somite is wider than long (this feature is shared with four congeners); (2) the caudal ramus is less than twice as long as wide (shared with three congeners); (3) the proximal seta on the basis (second segment) of the maxilliped bears unornamented (naked) proximal margin (shared with five congeners); (4) the same seta bears unornamented distal margin (this is a unique feature of the new species); (5) the exopodal segment of leg 5 lacks any process or denticle on its inner margin (shared with eight congeners); and (6) the exopodal segment of leg 5 is armed with 2 setae, without spine (shared with about nine congeners).

Kelleria robusta n. sp. most closely resembles Kelleria multiovigera Kim, 2009 known from Madagascar ( Kim, 2009) in the respect that the two species share five (1, 2, 3, 5, and 6) of the above six features, the greatest degree of sharing. Their caudal rami, antennae, labrum, and mandibles are very alike in form, as well. Nevertheless, they cannot be treated as conspecific due to two significant differences. Firstly, the proximal four spines on the distal margin of the maxillary endopod are subequal in size in Kelleria multiovigera , whereas those of Kelleria robusta n. sp. are very unequal. Secondly, the distal element (lash) on the endopod (third segment) of the female maxilliped of Kelleria multiovigera is setiform, elongate, much longer than the second segment (basis), whereas the same element of Kelleria robusta n. sp. is spiniform and distinctly shorter than the second segment.

Kelleria robusta n. sp. may be distinguished from other species of Kelleria by its outstanding feature (the above feature 4), although two species Kelleria propinqua ( Scott, 1894) and Kelleria rubimaculata Krishnaswamy, 1952 are not known of the ornamentation of the maxilliped setae. The latter two species are, however, not confusable with Kelleria robusta n. sp., because they have leg 5 in which the exopodal segment bears 2 distal spines (not setae as in the new species) and one or two cusps or processes on the inner margin ( Krishnaswamy, 1952; Scott, 1984).

It is notable that the ornamentation of the setae on the basis of the maxilliped is consistent within a species of Kelleria .

Figures

Fig. 11. Kelleria robusta n. sp., female.A, habitus, dorsal; B, urosome, dorsal; C, caudal rami, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule; J, maxilla. Scale bars:A, 0.5 mm; B-G, 0.1 mm; H-J, 0.05 mm.

Fig. 12. Kelleria robusta n. sp., female.A, maxilliped; B, leg 1; C, leg 2; D, endopod of leg 3; E, leg 4; F, exopod of leg 5; G, genital aperture. Scale bars:A, F, G, 0.05mm; B-E, 0.1 mm.