Clunia cocosensis, Harris, 2014

Harris, Vernon A., 2014, Porcellidiidae of Australia (Harpacticoida, Copepoda). III. Synopsis of Genera and Species, Records of the Australian Museum 66 (2), pp. 167-196 : 183-185

Clunia cocosensis sp. nov.

Figs 10 –11

Type material. HOLOTYPE adult female, length 1.06 mm, P81219 ; PARATYPE specimens (adult female and dissected female on slide) P81220, deposited at AM, Sydney. All collected from Cocos (Keeling) Islands, Indian Ocean, F. H. Talbot, 1979 .

Diagnosis. Female cephalosome hemi-elliptical; dorsal cuticle almost devoid of pits; anterior lobe of mandibular palp long, without ventral setules, molar process modified as a scraper; single seta on maxillule exopod long, not bulbous, endopod with one seta, endite formula 2-3-1; first dorsal seta on P5 exopod close to lateral seta, apical seta pinnate.

Biometric data. Females (N = 3): maximum length (Lmax) 1.03, 1.06, 1.09 mm, body length (Lurs) 0.94, 0.97, 0.99 mm; cephalosome width 0.65 mm; rostrum width 0.137 mm; genital double-somite 0.35 mm wide, 0.24 mm long: caudal ramus 0.12 mm long, 0.08 mm wide.

Ratios: Lurs / W 1.5, Lmax / W 1.6, W/ R 4.75 ; genital doublesomite w/l 1.46; caudal ramus 12.4% of Lurs, caudal ramus l/ w 1.5, Hicks’ index for α 80%, for β 68 %.

Description. Adult female (P81219, Fig. 10A ). Natural colour unknown, specimens have light brown oil (?) droplets in body cavity. Rostrum not prominent, no lens in rostrum, dorsal pits small (3µm) near edge of cephalosome, metasome segments and P5. Hyaline border clear, 12 µm wide. Genital double-somite (Fig. 11D) not broad, pointed posteriorly, lateral edge almost straight with no trace of division into anterior and posterior lobes, border setules absent except at apex, posterior arch less than 1/2 length of genital doublesomite. Caudal ramus ( Fig. 10G ) pentagonal, maximum width about 2/3 down ramus, posterior border straight, 90° to medial edge. A diagonal ridge runs from proximal medial corner to insertion of T2 seta. Terminal setae T1, T2, T4 pinnate, T1 and γ recessed on beveled edge, T4 at medial corner, T3 absent. Terminal fringe of setules between T2 and T4 2/3 maximum width of ramus. Structure and setation of mouthparts and ambulatory limbs typical of family. Exopod of antenna with five plumulose setae and one spinous seta, endopod segment 2 with three lateral setae, first terminal seta short, geniculate setae with plain end section, claw comb-like ( Fig. 10E ). Cutting edge of mandible molar process modified into trowel-like scraping organ without anterior seta or lappet ( Figs 10B, C ). Precoxa of maxillule elongate, endites bear 2-3-1 setae respectively, single plain seta on endopod and exopod ( Fig. 10D ). Maxilla (Fig. 11F) claw on endopod not broad or serrate, maxilliped ( Fig. 10F ). Conspicuous crescent of setules on segment 1 of P1 exopod (Fig. 11E), endopod with small but conspicuous triangle of setules at lateral end of fimbriate crescent. Spinous setules on external edge of P2, P3 and P4 exopod segments 1 and 2 appear to lie in a double row of about 9 + 9 setules (Figs 11A, C, G), segment 1 has a proximal row of nine fine setules and segment 3 has five or six setules. Serrated spinous seta on segment 2 of P3 shorter than endopod, large serrated spinous seta on segment 3 strong (Fig. 11C) longer than endopod (1.4:1). Spinous setae on P4 endopod segments 2 and 3 plain (Fig. 11G). P5 exopod lanceolate, not truncated posteriorly, two dorsal setae (first located verY close to lateral seta—a position not known elsewhere in the Porcellidiidae ) and one pinnate apical seta (Fig. 11B), border setules strong, P5s reach just beyond genital double-somite. One of the specimens has four large eggs in the brood chamber.

Adult male (no specimen available).

Etymology. Named from the Cocos Islands where the species was collected.

Remarks. The absence of a male animal renders the above description incomplete. The position of the first dorsal seta close to the lateral seta on the female P5 is unusual and has not been observed on any other member of the family.

Distribution. The four female specimens were collected at a depth of 4 m from dead coral encrusted with algae in a channel at the reef crest between Direction Island and Prison Island, Cocos (Keeling) Islands, Indian Ocean, F. H. Talbot, 8 Oct. 1979.

Figure 11. Clunia cocosensis sp. nov. Female: (A) P2; (B) P5 (ventral); (C) P3; (D) urosome; (E) P1; (F) maxilla; (G) P4. Scale bar: A, C, G = 0.1 mm. B = 0.23 mm. D = 0.3 mm. E, F = 0.08 mm.

Figures

Figure 10. Clunia cocosensis sp. nov. Female: (A) adult; (B, C) mandible and detail of molar process; (D) maxilla; (E) antenna; (F) maxilliped; (G) caudal ramus (with diatoms on dorsal surface). Scale bar:A = 0.6 mm. B, C, D = 0.08 mm. E = 0.06 mm. F, G = 0.1 mm.