Epigonus bispinosus, Okamoto & Gon, 2018

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 : 267-270

Epigonus bispinosus n. sp.

(New English name: Two-spined Deepwater Cardinalfish) ( Figs. 3 , 5 , 6A , 7A ; Tables 1–3)

Holotype. SAIAB 189476 , 165.5 mm SL, male, 11°58.41 S, 49°22.26 E, off northern Madagascar, western South Indian Ocean, 453–455 m depth, bottom trawl, 1 October 2009, collected by S. Fennessy.

Paratypes. 8 specimens, 34°13.47 S, 26°37.59 E, east of Port Elizabeth , South Africa, western South Indian Ocean, 250 m depth, bottom trawl, 2–3 June 1989. BMNH 2017.6 .9.1, 135.6 mm SL; KAUM-I . 102566, 141.7 mm SL; SAIAB 35606, 5 specimens, 102.6–156.0 mm SL; USNM 438974, 130.9 mm SL.

Diagnosis. A species of Epigonus with the following combination of characters: dorsal-fin rays VII-I, 10; pectoral-fin rays 15–16; total gill rakers 31–33; vertebrae 10 + 15; pyloric caeca 9–11; pored lateral-line scales 46– 50 + 4–5; scales weakly ctenoid; scales below lateral line 11; pungent opercular spine present; maxillary mustachelike process absent; ribs on last abdominal vertebra present; and two small spines present on symphysis of lower jaw.

Description. Counts and measurements of holotype and paratypes are shown in Tables 1–3. Body elongate, laterally compressed, deepest at pectoral-fin base; nape not humped ( Fig. 5A ). Head large, broad. Maxillary mustache-like processes absent. Snout short and round, length slightly longer than interorbital width; nostrils closely set at level of upper edge of pupil, anterior nostril without membranous tube, posterior nostril elliptical without dermal flap. Eye large, oval, orbital diameter greater than postorbital length; bony rim of orbit slightly raised above dorsal profile; interorbital region broad, flat. Mouth large, terminal; gape oblique; posterior margin of maxilla not extending to below center of pupil; lower jaw projecting when mouth closed; two small anterior projecting spines present on symphysis of lower jaw (one spine broken in holotype) ( Fig. 6A ). Teeth minute, a single row on maxilla and dentary. Small number of minute teeth present on vomer and palatine. Basihyal toothless. Opercular spine strong, pungent, forming ridge; posterior corner of preopercule weakly serrated. Origin of first dorsal fin above anterior part of pectoral fin; first dorsal-fin spine tiny; third and fourth dorsal-fin spines longest; no isolated dorsal-fin spine between first and second dorsal fins. Spine of second dorsal fin long, slightly thicker than those of first dorsal fin. Origin of anal fin below about center of second dorsal-fin base; first anal-fin spine minute; second anal-fin spine long, slightly longer than second dorsal-fin spine. Proximal radial of first analfin pterygiophore broad. Pectoral and pelvic fins short, posterior tip of fins not reaching vertical drawn from anus; upper margin of pectoral-fin base lower than level of horizontal line through center of pupil. Caudal fin deeply forked. Anus located slightly anterior to vertical drawn through origin of second dorsal fin. Ribs present on last abdominal vertebra. Supraneural bones three (0+0/0+2/1+1/1/). Scales large, deciduous, weakly ctenoid ( Fig. 7A ), covering whole body except for area anterior to rim of orbit and surfaces of jaws; small scales also present on bases of second dorsal, anal, and caudal fins; series of pored lateral-line scales complete, 4–5 pored scales on caudal fin. Ventral luminous organ absent.

Color in alcohol. Body, pectoral fins, and head (except gill cover which is dark brown) light brown; first dorsal, second dorsal, pelvic, and caudal fins dark brown; oral cavity and tongue tan.

Distribution. The species was collected off Eastern Cape coast ( South Africa) and off northern Madagascar ( Fig. 3 ), at a depth of 250– 455 m.

Etymology. The specific name “ bispinosus ” means two spines, in reference to the spines found on the symphysis of the lower jaw ( Fig. 6A ).

Comparisons and Remarks. Epigonus bispinosus belongs to the E. constanciae group by having a pungent opercular spine ( Okamoto & Motomura 2011). Besides E. bispinosus , this species group comprises another 21 species ( Okamoto 2016a; Fricke 2017; present study). Epigonus bispinosus is unique in the species group in having two spines on the symphysis of lower jaw. In addition to the diagnostic character, E. bispinosus differs from 19 species of the group in having 10 + 15 vertebrae ( Fig. 5B ) (vs. 11 + 14 in E. chilensis , E. crassicaudus , E. heracleus , E. lenimen , E. machaera , and E. robustus ), 10 soft rays on the second dorsal fin (vs. 9 soft rays on the second dorsal fin in E. affinis , E. elegans , and E. waltersensis ), 31–33 gill rakers (vs. 20–26 gill rakers in E. atherinoides , E. ctenolepis , E. draco , E. megalops , E. okamotoi , E. occidentalis ), a pair of ribs on the last abdominal vertebra (vs. ribs absent on the last abdominal vertebra in E. marimonticolus and E. thai ), and in lacking a pair of maxillary mustache-like processes (vs. a pair of sharp-pointed processes present in E. constanciae , E. mayeri , and E. pectinifer ). Another new species in the present study, E. idai , differs from E. bispinosus by having 4–5 tiny projection on the symphysis of lower jaw (vs. two spines present in E. bispinosus : Fig. 6A ), 18–19 pectoral-fin rays (vs. 15–16), and strongly ctenoid scales (vs. weakly ctenoid: Fig. 7A ).

Figures

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

FIGURE 5. Lateral view (A) and radiograph (B) of Epigonus bispinosus n. sp., SAIAB 189476, holotype, 165.5 mm SL.

FIGURE 7. Pored lateral-line scales. A: Epigonus bispinosus n. sp., SAIAB 189476, holotype, 165.5 mm SL; B: E. idai, n. sp., SAIAB 204434, paratype, 132.3 mm SL.

FIGURE6. Ventral viewof symphysis of lowerjaw.A:Epigonus bispinosusn. sp., SAIAB35606, 1of 5 paratypes,141.7 mm SL; B: Epigonus idai n. sp., SAIAB 204434, paratype, 132.3 mm SL.