Kelleria andamanensis Sewell, 1949

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 : 369-373

Kelleria andamanensis Sewell, 1949 ( Figs. 4-6 )

Syn.: Kelleria andamanensis Sewell, 1949, p. 112 , textfig. 7.

Kelleria grandisetiger Kim, 2006, p. 1 , figs. 1, 2.

Material examined. 2 ŞŞ, 5 ♂♂ collected with a light trap, shallow subtidal, 5°21′27.17″N, 162°57′51.23″E, Kosrae, Micronesia, by J. Lee, 2 July 2016 .

Female. Body ( Fig. 4A ) moderately broad. Body length of dissected specimen 1.34 mm. Prosome 680 μm long, half as long as body length. All prosomal somites bearing blunt lateral corners. Cephalothorax 490 × 423 μm. Fifth pedigerous somite as wide as genital double-somite, characteristically bearing digitiform posterolateral process near base of exopod of leg 5 ( Fig. 5F and as indicated by arrowhead in Fig. 4B ). Genital double-somite slightly longer than wide (220 × 200 μm), gradually narrowing distally; genital apertures large, positioning laterally, with 2 small, naked setae on genital operculum and 1 large, feebly spinulose seta positioning at middle of lateral margin of double-somite. Three free abdominal somites 68 × 103, 48 × 97, and 64 × 100 μm, respectively. Caudal ramus ( Fig. 4C ) 2.23 times longer than wide (89 × 40 μm), strongly tapering along its distal third, with pore at distal apex, and armed with 6 setae; outer seta (seta II) naked, positioning at 52% region of outer margin; small dorsal seta (seta VII) also naked; other 4 setae pinnate. Egg sac ( Fig. 4D ) oval, 364 × 195 μm; each egg 64 μm in diameter.

Rostrum ( Fig. 4E ) strongly tapering, with round distal apex. Antennule ( Fig. 4F ) 7-segmented; armature formula 4, 13, 6, 3, 4 + aesthetasc, 2 + aesthetasc, and 7 + aesthetasc; setae thin and naked; aesthetascs thin, setiform. Antenna ( Fig. 4G ) slender, 4-segmented; armature formula 1, 1, 2 + claw, and 5 + 2 claws; claws slender, geniculate near middle, with fine spinules along inner margin; second and terminal segments (first and third endopodal segments) ornamented with fine spinules along outer margin; terminal segment (third endopodal segment) 3.95 times longer than wide (83 × 21 μm).

Labrum ( Fig. 4H ) with deep posteromedian incision and broad posterolateral lobes. Mandible ( Fig. 4I ) with elongate, serrate distal lash, about 14 teeth along convex outer margin of gnathobase, 8 spinules along inner margin, and tuft of spinules consisting of 5 longer and 3 or 4 shorter spinules on convex side near base of gnathobase; convex margin proximal to gnathobase bearing narrow membranous fringe. Maxillule ( Fig. 4J ) as elongate lobe armed with 4 setae, consisting of 2 longer distal setae, 1 shorter subdistal seta, and 1 naked, process-like inner margin seta. Maxilla ( Fig. 4K ) consisting of syncoxa and basis; syncoxa unarmed; basis with spiniform distal lash (or process), large spiniform inner seta (seta I) bearing 6 spinules on both margins, slender anterior seta (seta II), rudimentary proximal seta (set III), and 7 unequal spines along distal margin arranged as 1 large, 3 small, 2 large, and 1 small from proximal to distal; small last spine locating on distal lash; distal lash incompletely articulated basally. Maxilliped ( Fig. 5A ) 3-segmented; first segment (syncoxa) the longest but unarmed; second segment (basis) with a small angle on outer margin, and armed with 2 large setae on inner margin, proximal seta naked along proximal margin but with row of about 15 large spinules along distal margin, distal seta slightly longer than proximal seta, ornamented with fine spinules along both margins; third segment (endopod) small, armed with 4 elements consisting of small outer spine, small, naked inner proximal seta, pinnate inner distal seta, and elongate, wrinkled, process-like apical seta.

Legs 1-3 with 3-segmented rami ( Fig. 5B, C ). Leg 3 same as leg 2 except bearing 3 spines and 2 setae on third endopodal segment ( Fig. 5D ). Leg 4 ( Fig. 5E ) with 3-segmented exopod and 1-segmented endopod; endopodal segment 2.84 times longer than wide (91 × 32 μm), with 1 cusp on outer margin, patch of spinules on outer side distal to cusp, and dentiform outer distal corner; 2 distal spines 41 (outer) and 59 μm long (inner), respectively; inner seta short, not extending to distal margin of endopodal segment. Armature formula for legs 1-4 as in Kelleria regalis .

Leg 5 ( Fig. 5F ) consisting of 1 pinnate dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment 2.57 times longer than wide (77 × 30 μm), slightly broadened in proximal half, with 1 cusp on distal margin, and armed with 2 naked distal setae, outer one of which annulated proximally. Leg 6 ( Fig. 5G ) represented by 2 small setae on genital operculum and 1 large, separated seta on lateral margin of genital double-somite.

Male. Body ( Fig. 6A ) narrower than that of female. Body length 1.15 mm. Dorsal suture line between cephalosome and first pedigerous somite incomplete. Urosome ( Fig. 6B ) 6-segmented. Genital somite distinctly wider than fifth pedigerous somite, 150 × 146 μm. Four abdominal somites 68 × 82, 59 × 77, 39 × 70, and 52 × 77 μm, respectively. Caudal ramus 2.22 times longer than wide (80 × 36 μm).

Rostrum as in female. Antennule with 3 additional aesthetascs at places indicated by dark circles in Fig. 4F . Antenna armed as in female, but terminal segment 3.22 times longer than wide (74 × 23 μm), shorter than that of female.

Labrum, mandible, and maxillule as in female. Maxilla ( Fig. 6C ) slightly different from that of female in arrangement of spines on distal margin of basis; these spines 7 or 8 in number and arranged as 1 large, 2 small, 2 large, 1 or 2 small, and 1 large from proximal to distal; distal lash not articulated at base. Maxilliped ( Fig. 6D ) consisting of 3 segments and terminal claw; first segment (syncoxa) unarmed; second segment (basis) with triangular expansion and 2 unequal setae on inner margin, and numerous spinules on inner surface; small third segment unarmed; terminal claw elongate, arched, longer than combined proximal 3 segments, bearing 2 unequal setae proximally.

Leg 1 ( Fig. 6E ) with third endopodal segment armed with 2 spines and 4 setae (armature formula I, I, 4); 2 distal spines unequal in length, outer one about 1.3 times longer than inner one. Third endopodal segment of leg 2 slightly sexually dimorphic; mid-terminal process bicuspid, and outer spine elongated and almost naked. Legs 3 and 4 as in female.

Leg 5, exopodal segment ( Fig. 6G ) 2.0 times longer than wide (30 × 15 μm), with convex inner margin, armed distally with 2 unequal, naked setae, inner seta 26 μm long and outer seta 52 μm long. Leg 6 ( Fig. 6H ) represented by 2 setae (1 pinnate and 1 naked) of equal length and 1 small cusp on genital operculum.

Remarks. Our specimens from Kosrae are identifiable with Kelleria grandisetiger Kim, 2006 which was recorded from Korea ( Kim, 2006). This disjunct distribution of the species leaded us to a close comparison between this and other known species and a reconsideration to the validity of Kelleria grandisetiger . Kim (2006) differentiated Kelleria grandisetiger from its close relative Kelleria andamanensis Sewell, 1949 known from the Andaman Islands ( Sewell, 1949) by different forms of the caudal rami and mandible. However, these differences seem not enough to recognize them as separate species. Sewell (1949) described and illustrated a row of “5 long spinelike teeth” on the convex outer side of the mandible, which are interpretable as a schematic expression of the tuft of 5 thin spinules (other 3 or 4 smaller spinules were overlooked) exhibited in our specimens and Kelleria grandisetiger . Kelleria grandisetiger is here synonymized with Kelleria andamanensis .

As diagnostic features of Kelleria andamanensis , (1) the fifth pedigerous somite of the female bears a pair of the digitiform posterolateral processes; (2) the genital double-somite in the female has a large seta (as an element of leg 6) on the lateral margin; (3) the distal margin of the maxillary endopod of the female is armed with 7 spines arranged as 1 large, 3 small, 2 large, and 1 small ones from proximal to distal; (4) the proximal seta on the second segment (basis) of the female maxilliped is naked along proximal margin but ornamented with about 15 large spinules along distal margin; and (5) the mandible bears a tuft of 5 longer and 3 or 4 shorter, thin spinules on convex outer side.

Figures

Fig. 4. Kelleria andamanensis Sewell, 1949, female.A, habitus, dorsal; B, urosome, dorsal; C, caudal rami, dorsal; D, egg sac; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule; K, maxilla. Scale bars:A, B, D, 0.1 mm; C, E-H, K, 0.05mm; I, J, 0.02mm.

Fig. 5. Kelleria andamanensis Sewell, 1949, female.A, maxilliped; B, leg 1; C, leg 2; D, third endopodal segment of leg 3; E, leg 4; F, leg 5; G, right side of genital double-somite, dorsal. Scale bars: 0.05 mm.

Fig. 6. Kelleria andamanensis Sewell, 1949, male. A, habitus, dorsal; B, urosome, ventral; C, maxilla; D, maxilliped; E, leg 1; F, endopod of leg 2; G, exopod of leg 5; H, leg 6. Scale bars:A, 0.2 mm; B, 0.1 mm; C-F, H, 0.05mm; G, 0.02 mm.