Kelleria regalis Gurney, 1927

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 : 365-369

Kelleria regalis Gurney, 1927 ( Figs. 1-3 )

Syn.: Kelleria regalis Gurney, 1927, p. 471 , figs. 116, 117; Humes & Ho, 1969, p. 221, figs. 1-30.

Kelleria javaensis Mulyadi, 2009, p. 1373 , figs. 6, 7.

Material examined. 6 ŞŞ, 1 ♂ collected with a light trap, shallow water, 5°21′22.31″N, 162°57′46.59″E, Kosrae Island , Micronesia, 30 June 2016, Jimin Lee .

Female. Body ( Fig. 1A ) consisting of moderately broad prosome and slender urosome. Body length 1.25 mm. Maximum width 500 μm across cephalothorax. Prosome 677 μm long, consisting of cephalothorax and second to fourth pedigerous somites. Cephalothorax 478 μm long, with faint dorsal suture line delimiting cephalosome and first pedigerous somite; posterolateral corners of first pedigerous somite bluntly projected. Second pedigerous somite fringed with narrow membrane along posterolateral corners. Third and fourth pedigerous somites fringed with narrow membrane along lateral margins. Urosome ( Fig. 1B ) 5-segmented. Fifth pedigerous somite slightly wider than genital double-somite. Genital double-somite 1.43 times longer than wide (218 × 152 μm), with slightly broadened anterior third. Genital apertures positioning dorsolaterally at third of double-somite length. Three free abdominal somites 91 × 95, 67 × 90, and 50 × 84 μm, respectively. Genital double-somite and first and second free abdominal somites fringed with wavy membrane along posterior borders. Caudal ramus ( Fig. 1C ) 2.37 times longer than wide (83 × 35 μm), armed with 6 setae; lateral seta (seta II) naked and stiff, tipped with setule; small dorsal seta (seta VII) also naked; other 4 setae pinnate.

Rostrum ( Fig. 1D ) strongly tapering, with round distal apex. Antennule ( Fig. 1E ) 7-segmented, gradually narrowing from proximal to distal; armature formula 4, 13, 6, 3, 4 + aesthetasc, 2 + aesthetasc, and 7 + aesthetasc; all setae naked, generally long and thin; aesthetascs also thin, setiform. Antenna ( Fig. 1F ) slender, 4-segmented, consisting of coxobasis and 3-segmented endopod; terminal segment (third endopodal segment) about 4.0 times longer than wide (91 × 23 μm); armature formula 1, 1, 2 + claw, and 5 + 2 claws; claws thin, setiform, geniculate near middle.

Labrum ( Fig. 1G ) with broad and deep posteromedian incision and round posterolateral lobes. Mandible ( Fig. 1H ) comprising gnathobase and distal lash; blade broad, with tuft of more than 15 needle-like spinules on convex outer side, about 10 large teeth along convex outer margin, 10 spinules (including smaller fifth and sixth ones) on inner margin; distal lash articulated from gnathobase, with fine spinules along both margins. Paragnath ( Fig. 1I ) as small, setulose lobe. Maxillule ( Fig. 1J ) lobate, armed with 4 unequal setae, 3 on distal margin and 1 on inner margin. Maxilla ( Fig. 1K ) consisting of syncoxa and basis; syncoxa unarmed but bearing claw-like process anterodistally (indicated by arrowhead in Fig. 1K ); basis with 3 setae and spiniform, articulating distal lash; inner seta (seta I) large, spiniform, bearing about 10 spinules along distal margin and 9 spinules along proximal margin; anterior seta (seta II) simple, unornamented; proximal seta (seta III) rudimentary; distal margin of basis with 4 large and 3 or 4 small spines, 2 small ones of them positioning on distal lash. Maxilliped ( Fig. 2A ) 3-segmented; first segment (syncoxa) unarmed, but bearing small membranous flap (indicated by arrowhead in Fig. 2A ) subdistally on inner surface; second segment (basis) with 2 large, spiniform setae on inner margin, both setae finely spinulose along distal margin, patch of spinules (distal one of them large) on proximal region of proximal margin; third segment (endopod) with 4 large setae consisting of outer, apical, and 2 inner; outer and inner distal setae subequal in length, spinulose along both margins, longer than segment; inner proximal seta elongate, more than twice length of segment, finely spinulose along distal margin; apical seta (distal lash) naked, wrinkled.

Legs 1-3 with 3-segmented rami ( Fig. 2B, C ). Leg 3 similar to leg 2, except its third endopodal segment ( Fig. 2D ) armed with fewer setae on inner margin. Leg 4 ( Fig. 2E ) with 3-segmented exopod and 1-segmented endopod; endopodal segment 2.9 times longer than wide (78 × 27 μm), with small cusp on outer margin; 2 distal spines 80 (inner) and 44 μm long (outer); inner seta not extending to distal margin of endopodal segment. 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; II, I, 5 0, II, 1

Leg 5 consisting of small, pinnate dorsolateral seta on fifth pedigerous somite and free exopod ( Fig. 1B ); exopodal segment ( Fig. 2F ) 1.9 times longer than wide (126 × 66 μm), spinulose along inner and outer margins, with 1 minute cusp on outer margin, 1 digitiform process on inner margin, 1 cusp and 1 digitiform process on distal margin (latter process indicated by arrowhead distinct or indistinct), and armed distally 1 spine (72 μm long) and 1 geniculate seta (56 μm long). Leg 6 ( Fig. 2G ) positioning in genital aperture, represented by 1 small seta and 1 spinule on dorsal side and 1 large seta and 1 small cusp on lateral process.

Male. Body ( Fig. 3A ) similar to that of female, 1.10 mm long. Dorsal suture line obscure between cephalosome and first pedigerous somite. Urosome ( Fig. 3B ) 6-segmented. Fifth pedigerous somite 105 μm wide, narrower than genital somite. Genital somite slightly longer than wide (148 × 139 μm). Four abdominal somites 68 × 68, 66 × 61, 49 × 57, and 45 × 63 μm, respectively. Caudal ramus 2.57 times longer than wide (77 × 30 μm).

Rostrum as in female. Antennule with 3 additional aesthetascs, 2 on second and 1 on fourth segments, as indicated by dark circles in Fig. 1E . Antenna as in female.

Labrum, mandible, and maxillule as in female. Maxilla ( Fig. 3C ) lacking anterodistal claw-like process on syncoxa; basis with spiniform distal lash and 3 large and 4 or 5 small spines on distal margin, arranged as 1 large, 2 small, 1 large, and 2 or 3 small from proximal to distal, and 1 large spine on distal lash. Maxilliped ( Fig. 3D ) consisting of 3 segments and terminal claw; first segment (syncoxa) unarmed; second segment (basis) armed proximally with 2 small setae (proximal one of them strongly curved, domino-shaped, and finely spinulose along convex margin, as shown in Fig. 3E ) and ornamented with 2 longitudinal rows of spinules on inner surface (shorter row of short spinules and longer row of long spinules); small third segment unarmed; terminal claw gently arched, elongate, with membranous fringe along concave inner margin and proximally 1 slender seta and 1 minute setule.

Leg 1 ( Fig. 3F ) endopod geniculate between second and third segments; third endopodal segment armed with 2 spines (outer and terminal) and 4 inner setae; terminal spine ornamented with broad, leaf-like spinules along both margins. Third endopodal segment ( Fig. 3G ) of leg 2 with fleshy outer distal process (indicated by arrowhead in Fig. 3G ); outer distal spine almost naked. Legs 3 and 4 as in female.

Leg 5 exopodal segment ( Fig. 3H ) nearly rectangular, 2.0 times longer than wide (30 × 15 μm), with slightly convex inner margin; distal spine and seta 36 and 37 μm long, respectively. Leg 6 ( Fig. 3I ) represented by 2 setae (1 naked and 1 pinnate) and 1 cusp on distal apex of genital operculum.

Remarks. Gurney (1927) originally recorded Kelleria regalis discovered from the Suez Canal. Humes & Ho (1969) redescribed this species in detail on the basis of samples collected from Madagascar. The female maxilliped of Kelleria regalis exhibits characteristic morphological features of this species; its first segment (syncoxa) bears a peculiar subdistal membranous flap and the third segment (endopod) is armed with unusually large setae. Our specimens from Kosrae also exhibit these characteristic features. Kelleria javaensis Mulyadi, 2009 recorded from Indonesia ( Mulyadi, 2009) also has the same form of the female maxilliped. The forms of the body, maxilla, and leg 5 exopod of Kelleria javaensis are not significantly different either from the specimens of Humes & Ho (1969) and ours. Kelleria javaensis is here synonymized with Kelleria regalis which is now proved to be a widely distributed species in the Indo-West Pacific.

Figures

Fig. 1. Kelleria regalis Gurney, female. A, habitus, dorsal; B, urosome, dorsal; C, left caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, paragnath; J, maxillule; K, maxilla. Scale bars:A, 0.2 mm; B, 0.1 mm; C-G, K, 0.05 mm; H-J, 0.02mm.

Fig. 2. Kelleria regalis Gurney, female.A, maxilliped; B, leg 1; C, leg 2; D, third endopodal segment of leg 3; E, leg 4; F, exopod of leg 5; G, left genital aperture, dorsal. Scale bars: A, C-F, 0.05mm; B, 0.02mm.

Fig. 3. Kelleria regalis Gurney, male. A, habitus, dorsal; B, urosome, ventral; C, maxilla; D, maxilliped; E, proximal seta on basis of maxilliped; F, leg 1; G, third endopodal segment of leg 2; H, exopod of leg 5; I, leg 6. Scale bars:A, 0.2 mm; B, 0.1 mm; C, G-I, 0.02mm; D, F, 0.05mm; E, 0.01 mm.