Epigonus waltersensis Parin & Abramov, 1986

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 : 285-286

Epigonus waltersensis Parin & Abramov, 1986

(New English name: Walters Shoals Deepwater Cardinalfish) ( Figs. 3 , 19 ; Tables 1, 2)

Epigonus waltersensis Parin & Abramov, 1986b: 182 , fig. 4 (original description; type locality: 33°06 S, 44°04 E, Walters Shoals, Madagascar submarine ridge, 740–760 m depth; holotype: ZIN 47335); Abramov, 1992: 100 (key); Okamoto & Fukui, 2011: 391 (key); Okamoto, 2012: 252, fig.10n (photograph and key, based on original description).

Material examined. ZIN 47335, holotype, 129.0 mm SL, Walters Shoals , Madagascar submarine ridge, 33°06 S, 44°04 E, 740–760 m depth, 25 June 1979 (photograph and radiograph).

Diagnosis. Dorsal-fin rays VII-I, 9; pectoral-fin rays 17–18; total gill rakers 32; vertebrae 10 + 15; pyloric caeca 6; pored lateral-line scales 48; pungent opercular spine present; maxillary mustache-like processes absent; nub-like structures or spine on symphysis of lower jaw absent; ribs on last abdominal vertebra present; anus just below origin of second dorsal fin; tongue toothless; body depth 24.2% SL.

Measurements (% SL); counts are given in Table 1. Head length 35.9; head height 21.7; body depth 24.2; body width 14.1; caudal-peduncle depth 10.2; caudal-peduncle length 29.2; orbital diameter 15.0; interorbital width 8.9; postorbital length 15.0; upper-jaw length 15.1; lower-jaw length 14.7; snout length 7.8; pre-first dorsalfin length 38.8; pre-second dorsal-fin length 59.2; pre-pectoral-fin length 36.8; pre-pelvic-fin length 38.2; pre-analfin length 67.3; first spine length on first dorsal fin 1.6; second spine length on first dorsal fin 12.8; second dorsalfin spine length 12.8; second anal-fin spine length 11.4; pelvic-fin spine length 12.5; first dorsal-fin base length 11.4; second dorsal-fin base length 8.3; anal-fin base length 7.4; pectoral-fin length 16.7; pelvic-fin length 14.3.

Distribution. Walters Shoals, western South Indian Ocean (Parin & Abramov 1986b), at 740–760 m depth.

Comparisons and Remarks. Epigonus waltersensis is so far known only from the holotype collected on the Madagascar submarine ridge (Parin & Abramov 1986b). The specimen has eight anal-fin soft rays (Table 1), an unusual condition in Epigonus . Mayer (1974) noted this condition as a rare occurrence in several species of Epigonus and the holotype of this species could be such a case in E. waltersensis . Okamoto (2012) moved the species from the E. robustus species group (sensu Parin & Abramov 1986b) to the E. constanciae group. This species is similar to E. pectinifer in having 10 + 15 vertebrae, 9 soft rays on the second dorsal fin, and 6 pyloric caeca; however, it differs in having 32 gill rakers and lacking a maxillary mustache-like processes (vs. 26–30 total gill rakers and a sharp-pointed maxillary mustache-like processes present in E. pectinifer ). Epigonus waltersensis can be distinguished from E. lenimen and E. robustus by having 10 + 15 vertebrae (vs. 11 + 14 in E. lenimen and E. robustus ). Epigonus marimonticolus and two new species described in the present study, E. bispinosus and E. idai , differ from E. waltersensis in having 10 soft rays on the second dorsal fin (vs. 9 in E. waltersensis ) and 10–15 pyloric caeca (vs. 6 in E. waltersensis ). Furthermore, E. waltersensis can be distinguished from the remaining 7 species of the genus in the Western Indian Ocean by having a pungent opercular spine ( Fig. 19 ).

Figures

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

FIGURE 19. Epigonus waltersensis, ZIN 47335, holotype, 129.0 mm SL.