Epigonus robustus ( Barnard, 1927 )

Okamoto, Makoto & Gon, Ofer, 2018, A review of the deepwater cardinalfish genus Epigonus (Perciformes: Epigonidae) of the Western Indian Ocean, with description of two new species, Zootaxa 4382 (2), pp. 261-291 : 282

Epigonus robustus ( Barnard, 1927)

(English name: Robust Cardinalfish; Robust Deepsea Cardinal) ( Figs. 3 , 17 ; Tables 1, 2)

Parahynnodus robustus Barnard, 1927: 70 (original description; type locality: off Cape Point, South Africa, 841 m depth; holotype: SAM 13080).

Epigonus robustus: Mayer, 1974: 189 , fig. 20 (description, Australia, South Africa); Mayer, 1975: 16 (brief description, South Atlantic); Gon, 1986: 559 ( South Africa); Nakamura, 1986: 200 (description and photograph, from southern Brazil to Argentine Patagonia); Parin & Abramov, 1986b: 189 (description, southern Australia, Western Indian Ocean, South Africa); Allen & Cross, 1989: 553 (list, Australia); Pequeño, 1989: 60 (list, Chile); Paulin, et al., 1989: 180 (key, New Zealand); Abramov, 1992: 100 (key); Gomon et al., 1994: 563 (key and brief description, southern Australia); Williams et al., 1996: 153 (list, Western Australia); Bianchi et al., 1999: (list, Namibia); Trunov, 1999: 466 (list, Atlantic Ocean); Hutchins, 2001: 32 (list, southern Australia); Hoese et al., 2006: 1114 (list, Australia); Gomon et al., 2008: 563 (list, Australia); Okamoto & Fukui, 2011: 391 (key); Okamoto, 2012: 252, fig. 10-m (key and photograph); Stewart & Gon, 2015: 1225: (description and photograph, New Zealand).

Material examined. SAM 13080, holotype, 170 mm SL, Off Cape Point, South Africa, 841 m depth, 841 m depth ; CSIRO H 5375-02, 184.7 mm SL, 39°01 S, 46°32 E, western South Indian Ocean , 776–1017 m depth, 12 November 1999 ; CSIRO H 5398-01, 176.7 mm SL, CSIRO H 5398-02, 3 specimens, 190.4–197.2 mm SL, 39°01 S, 46°32 E, western South Indian Ocean , 712–1067 m depth, 13 November 1999 ; SAIAB 38259 , 2 specimens, 150.7–155.0 mm SL, 32°24.05 S, 16°14.00 E, West Coast Slope , South Africa .

Diagnosis. Dorsal-fin rays VII-I, 9; pectoral-fin rays 16–18; total gill rakers 29–33; vertebrae 11 + 14; pyloric caeca 6–7; pored lateral-line scales 46–50 + 3–5; pungent opercular spine present; blunt maxillary mustache-like processes present; ribs on last abdominal vertebra present; tongue toothless; two nub-like structures present on symphysis of lower jaw.

Measurements (% SL); counts are given in Table 1. Head length 31.5–34.2; head width 15.0–17.1; head height 14.9–16.4; body depth 18.8–22.5; body width 13.6–16.2; caudal-peduncle depth 9.2–10.8; caudal-peduncle length 24.3–30.6; orbital diameter 12.2–14.3; interorbital width 7.3–8.4; postorbital length 12.5–15.3; upper-jaw length 12.6–14.4; lower-jaw length 14.0–15.3; snout length 6.3–7.7; pre-first dorsal-fin length 36.8–39.4; presecond dorsal-fin length 56.2–60.3; pre-pectoral-fin length 31.2–33.5; pre-pelvic-fin length 34.1–37.0; pre-anus length 55.4–61.4; pre-anal-fin length 62.4–71.8; first spine length on first dorsal fin 1.2–3.1; second spine length on first dorsal fin 10.7–16.0; third spine length on first dorsal fin 13.7–19.3; second dorsal-fin spine length 10.0– 15.7; first anal-fin spine length 2.5–4.4; second anal-fin spine length 10.7–16.3; pelvic-fin spine length 11.3–16.8; first dorsal-fin base length 10.3–13.6; second dorsal-fin base length 9.1–12.0; anal-fin base length 8.8–10.4; pectoral-fin length 18.8–21.4; pelvic-fin length 17.1–23.0.

Distribution. South Indian Ocean ( Mayer 1974; Gon 1986; Parin & Abramov 1986b; Abramov 1992); Australia ( Hoese et al. 2006; Gomon et al. 2008); New Zealand (Paulin et al. 1989; Stewart & Gon 2015); and western South Atlantic ( Nakamura 1986; Abramov 1992), at 500–1700 m depth.

Comparisons and Remarks. Epigonus robustus is a member of the E. constanciae group by having a pungent opercular spine ( Fig. 17A ). The species is similar to E. lenimen in having 11 + 14 vertebra; however, it differs from E. lenimen by having two nub-like structures on the symphysis of lower jaw (vs. absent in E. lenimen ) and the orbital diameter shorter than postorbital length (vs. orbital diameter longer than postorbital length in E. lenimen ). The other five species of the group in the Western Indian Ocean, E. bispinosus , E. idai , E. marimonticolus , E. pectinifer , and E. waltersensis , have 10 + 15 vertebrae (vs. 11 + 14 vertebrae in E. robustus ). Several years ago, the second author examined the holotype, or rather what of left of it ( Fig. 17C ). The specimen was collected on 20 August 1903 during marine surveys conducted in the period 1897–1904 by the Pieter Faure, the Government steam trawler, under the leadership of J.D.F. Gilchrist who was then Director of the Government’s Marine Biological Survey as well as Honorary Keeper of the Department of Marine Invertebrates of the South African Museum, Cape Town ( Gon & Skelton 1997). In addition to the parts of the fish shown in Fig. 17C , the jar of SAM 13080 contains scattered bones and scales of the specimens.

Figures

FIGURE 3. Distribution of seven species of the Epigonus constanciae group inthe Western Indian Ocean.

FIGURE17.Epigonus robustus, SAIAB 38259, 1of 2 specimens,155.0 mm SL.A:lateral view;B: ventral view of symphysis of lower jaw (arrows show the nub-like structures); C: SAM 13080, holotype, standard length unknown.