Sagum epinepheli

Sagum epinepheli (Yamaguti & Yamasu, 1960)

(Fig. 43)

Syn: Pseudolernanthropus epinepheli Yamaguti & Yamasu, 1960

Non Sagum epinepheli: Pillai & Sebastian, 1967

Material examined: 3♀♀ and 3♂♂ from Plectropomus leopardus (Lacepède, 1802), Townsville, Queensland, 01 March 2012, collected by K.S. Hutson; 2♀♀ and 2♂♂ QM Reg. No. W29503, 1♀ and 1♂ NHMUK Reg. No. 2018.216–217. 1♀ from Epinephelus coioides Hamilton, 1822, Bynoe Harbour, Northern Territory, 09 March 2014, collected by B.K. Diggles; MAGNT Reg. No. Cr 019248.

Differential diagnosis: Cephalothorax wider than long; mid-section of lateral margin produced into process on each side (Fig. 43 A–C). Trunk subrectangular, markedly wider than cephalothorax: anterior part of trunk (second and third pedigerous somites) wider than long, produced into tapering posterolateral processes extending almost halfway along lateral margins of dorsal trunk plate. Posterior part of trunk covered by square dorsal trunk plate with weakly convex sides, rounded corners and slight medial indentation in posterior margin. Entire dorsal surface of cephalothorax and trunk densely ornamented with small cuticular papillae. Urosome formed from fifth pedigerous somite, genital complex and abdomen. Egg sacs coiled beneath dorsal trunk plate. Paired caudal rami elongate, tapering towards acute tip. Leg 2 biramous, with unimerous rami. Leg 3 forming fleshy lamella, with large, lamellate outer lobe orientated near-vertically and expanded posteriorly, reaching almost to posterior end of body, connecting via short ventrally directed anterior lobe to elongate, lamellate and horizontally-orientated inner lobe. Leg 4 bilobate; both inner and outer lobes with foliaceous proximal part tapering abruptly to flagellate distal part; flagellate tips sometimes visible, extending beyond posterior margin of dorsal trunk plate (Fig. 43 A–C). Leg 5 absent. Mean body length of ♀ from P. leopardus 5.02 mm, range 4.89 to 5.14 mm (based on 3 specimens); mean body length of ♂ 1.70 mm, range 1.65 to 1.76 (based on 3 specimens): body length of ♀ from E. coioides 4.33 mm.

Distribution: Originally recorded in Japanese waters from Epinephelus akaara (Temminck & Schlegel, 1842) by Yamaguti & Yamasu (1960), this species has been reported subsequently from India on E. merra Bloch, 1793 (Pillai, 1985) and from Taiwan on E. awoara (Temminck, 1842) (Ho et al., 2011). Justine et al. (2010a) reported S. epinepheli from five grouper species: E. chlorostigma (Valenciennes, 1828), E. coeruleopunctatus (Bloch, 1790), E. cyanopodus (Richardson), E. merra, and E. morrhua (Valenciennes, 1833) caught in New Caledonia. Raja et al. (2018) have recently reported S. epinepheli from E. fasciatus (Forsskål, 1775) caught off the coast of southeastern India. In Australian waters this copepod occurs on Plectropomus leopardus and E. coioides. Sagum epinepheli was rare in wild E. coioides (n = 19) sampled from Bynoe Harbour over 5 half yearly sampling periods between August 2012 and March 2014, with prevalence ranging between 0% and 16.7% (mean intensity = 1), with no apparent seasonality.

Remarks: The original description of this species was based on females from Japan (Yamaguti & Yamasu, 1960). It has been redescribed in detail by Ho et al. (2011) and again by Izawa (2018). Pillai & Sebastian (1967) provided a description of females they attributed to S. epinepheli collected from an unidentified species of Epinephelus caught off Kerala, India but this was clearly a misidentification, as noted by Izawa (2018) who established a new species Sagum pillaisebastiani Izawa, 2018, to accommodate Pillai & Sebastian’s material. The description of the male attributed to S. epinepheli by Pillai (1985) actually refers to S. pillaisebastiani.