Kelleriella quadridens, 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 : 383-386

Kelleriella quadridens n. gen. n. sp. ( Figs. 13 , 14 )

Material examined. 6 ŞŞ from washings of invertebrates collected by SCUBA, Phu Quoc Island , Vietnam, 10°18′10.64″N, 103°51′20.18″E, 13 December 2016, J. Lee. Holotype (Ş, MABIK CR00247454 ) and paratypes (3 ŞŞ, MABIK CR00247455 ) have been deposited in the Marine Biodiversity Institute of Korea ( MABIK), Seocheon, Korea. Dissected paratypes (2 ŞŞ) are retained in the collection of IHK.

Female. Body ( Fig. 13A ) moderately broad. Body length 1.08 mm. Prosome fusiform, 754 × 505 μm. Cephalosome and first pedigerous somite divided by faint dorsal suture line. First and second pedigerous somites with angular posterolateral corners. Urosome ( Fig. 13B ) stout, 5-segmented. Fifth pedigerous somite 149 μm wide, as wide as genital double-somite. Genital double-somite wider than long (123 × 147 μm), with wider proximal half and narrower distal half; genital apertures large, positioning dorsally. Abdomen gradually narrowing distally. Three free abdominal somites 42 × 98, 38 × 89, and 45 × 84 μm, respectively. Caudal ramus ( Fig. 13C ) 2.0 times longer than wide (68 × 34 μm), with tapering distal margin, armed with 6 setae; outer and dorsal setae (seta II and VII) naked, other setae pinnate; outer seta positioning at 67% region of outer margin length.

Rostrum ( Fig. 13D ) strongly tapering, wider than long, with round distal apex. Antennule ( Fig. 13E ) gradually narrowing distally, 7-segmented; armature formula 4, 13, 6, 3, 4 + aesthetasc, 2 + aesthetasc, and 7 + aesthetasc; setae thin and naked; aesthetascs setiform; 4 setae (1 on second, 2 on fourth, and 1 on terminal segments) markedly long. Antenna ( Fig. 13F ) 4-segmented, consisting of coxobasis and 3-segmented endopod; armature formula 1, 1, 3, and 6 + claw; terminal (third endopodal) segment 2.3 times longer than wide (83 × 36 μm), with convex inner margin, ornamented with patch of spinules on subdistal inner surface; terminal claw ( Fig. 13G ) strong, recurved, with broadened proximal third; all setae on segments naked.

Labrum ( Fig. 13H ) with divergent, tapering posterolateral lobes and deep posteromedian incision. Mandible ( Fig. 13I ) with slender, elongate, spinulose distal lash, thin spinules (distal 3 of them thicker) along inner margin, tuft of 7 needle-like spinules on outer side near base of gnathobase, followed by 3 transversely arranged leaf-like spinules and row of about 13 teeth along outer margin. Maxillule ( Fig. 14A ) lobate and armed with 4 elements including 2 unequal apical setae (longer outer and shorter, spiniform inner), 1 large inner subdistal spiniform seta, and 1 setiform inner process. Maxilla ( Fig. 14B ) 2-segmented; proximal segment (syncoxa) large, markedly broadened, but unarmed; distal segment (basis) with short, thin, spiniform distal lash bearing 1 small denticle on its distal margin, 4 spines along distal margin, large spiniform inner seta (seta I) bearing spinules along its distal margin, broad anterior seta (seta II) bearing spinules along its inner margin, and rudimentary proximal seta (seta III). Maxilliped ( Fig. 14C ) 3-segmented; first segment (syncoxa) elongate, but unarmed; second segment (basis) bearing 2 spiniform setae, longer proximal one of them distally thin, curved; small third segment (endopod) with 1 slender seta, 1 shorter spinule-like seta, and 1 stout, basally articulated claw.

Legs 1-3 with 3-segmented rami ( Fig. 14D, E ). Leg 3 similar to leg 2, except bearing 3 spines and 2 setae (formula I, II, 2) on third endopodal segment. Leg 4 ( Fig. 14F ) with 3-segmented exopod and 1-segmented endopod; third exopodal segment armed with 4 spines and 5 setae; endopodal segment 2.62 times longer than wide (118 × 45 μm), bearing 2 cusps on outer margin (large, claw-like proximal and small spinule-like distal ones), armed with 2 distal spines and 1 inner seta; 2 distal spines 47 (outer spine) and 81 μm long (inner one), respectively; inner seta not extending to distal margin of segment. Outer seta on basis of legs 1-4 naked. Inner coxal seta of leg 4 minute, naked. All other seta on legs 1-4 pinnate. Armature formula for legs 1-4 as follows:

Coxa Basis Exopod Endopod

Leg 1 0-1 1-0 I-0; I-1; III, I, 4 0-1; 0-1; I, 1, 4 Leg 2 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 3 Leg 3 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 2 Leg 4 0-1 1-0 I-0; I-1; III, I, 5 0, II, 1

Leg 5 ( Fig. 13B ) consisting of large, naked dorsolateral seta on fifth pedigerous somite and 1-segmented, free exopod; exopodal segment ( Fig. 14G ) directed laterally, slightly curved, 2.0 times longer than wide (102 × 51 μm), consisting of broader proximal three-fifths and narrower distal two-fifths, armed distally with 2 naked setae, ornamented with spinules along convex outer margin; 2 distal setae comprising spiniform inner one (86 μm long) and wrinkled, setiform outer one (84 μm long). Leg 6 represented by 1 minute seta, 1 minute spinule, and 1 naked laterally displaced seta in genital aperture ( Fig. 13B ).

Male. Unknown.

Etymology. The specific name is a combination of the Latin words quadr (= four) and dens (= tooth), alluding to the presence of the four teeth on the distal margin of the maxillary endopod. Gender feminine.

Figures

Fig. 13. Kelleriella quadridens n. gen. n. sp., female.A, habitus, dorsal; B, urosome, dorsal; C, right caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, distal part of antenna; H, labrum; I, mandible. Scale bars:A, 0.2mm; B, E, 0.1mm; C, G, I, 0.02mm; D, F, H, 0.05mm.

Fig. 14. Kelleriella quadridens n. gen. n. sp., female.A, maxillule; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 4; G, exopod of leg 5. Scale bars:A-C, 0.02 mm; D-G, 0.05 mm.