Epigonus lifouensis Okamoto and Motomura, 2013

Okamoto, Makoto, 2018, First Records of Two Deepwater Cardinalfishes (Perciformes: Epigonidae), Epigonus lifouensis and E. pectinifer, from Indonesia, Eastern Indian Ocean, Species Diversity 23, pp. 243-248 : 243-245

Epigonus lifouensis Okamoto and Motomura, 2013 ( Fig. 1 ; Table 1)

Epigonus denticulatus (not of Dieuzeide): Inada and Wudianto 2006: 32 (photograph, off Sumatra, Indonesia).

Epigonus lifouensis Okamoto and Motomura, 2013: 302 , fig. 1 (original description, type locality: 21°40′59″S, 167°31′59″E, south of Lifou Island , Loyalty Islands, New Caledonia, western Pacific); Okamoto et al . 2018: (South China Sea, Taiwan).

Material examined. HUMZ 190770 (137.4 mm SL, male)–190771 (131.5 mm SL, male), 05°29′11″N, 94°01′47″E – 05°27′49″N, 94°01′52″E, off Sumatra, Indonesia, 347–361 m depth, 13 October 2004; HUMZ 191536–191545 , 10 specimens, 05°46′52″N, 102°41′25″E – 05°46′02″N, 102°39′53″E, off Sumatra, Indonesia, 546–639 m depth, 26 September 2004; ( HUMZ 191536, 170.1 mm SL, male; HUMZ 191537, 151.7 mm SL, male; HUMZ 191538, 162.8 mm SL, female; HUMZ 191539, 150.4 mm SL, male; HUMZ 191540, 143.2 mm SL, male; HUMZ 191541, 153.8 mm SL, male; HUMZ 191542, 180.7 mm SL, female; HUMZ 191543, 172.3 mm SL, male; HUMZ 191544, 156.7 mm SL, male; HUMZ 191545, 163.1 mm SL, male) .

Diagnosis. A species of Epigonus with the following combination of characters: dorsal-fin rays VII-I, 10; pectoral-fin rays 18–19; total gill rakers 24–28; vertebrae 10+15; pyloric caeca 10–13; pored lateral-line scales 47–49+4–5; body depth 17.0–20.1% SL; opercular spine absent; maxillary mustache-like processes absent; tongue toothless; ribs present on last abdominal vertebra; tubercle absent on inner symphysis of lower jaw; eye elliptical; and posterior half of oral cavity and tongue black.

Distribution. Known from New Caledonia ( Okamoto and Motomura 2013), South China Sea (Okamoto et al. 2018), and Indonesia (present study; Fig. 2 ), at depths of 347– 639 m.

Remarks. In the faunal study of demersal fishes in Indonesia ( Inada and Wudianto 2006), the present specimens from off Sumatra were identified as “ Epigonus denticulatus Dieuzeide 1950 ”. However, I re-examined the specimens and identified them as E. lifouensis in the present study ( Fig. 1 ). Epigonus lifouensis can be distinguished from E. denticulatus by having fewer gill rakers (24–28 vs. 28–34 in E. denticulatus ) and a black tongue and oral cavity (vs. tan; Dieuzeide 1950; Mochizuki 1982, 1990; Abramov 1992; Okamoto and Gon 2018). In the eastern Indian Ocean, E. denticulatus has been reported from the south of the Great Australian Bight ( Abramov 1992; Kamysheva 1985), but not from the north eastern Indian Ocean, to date.

Epigonus lifouensis was originally described based on two specimens from the south of Lifou Island , Loyalty Islands, New Caledonia ( Okamoto and Motomura 2013) . Later, a single specimen of the species was collected from a seamount nearby the Macclesfield Bank, South China Sea (Okamoto et al. 2018). The present specimens represent the first record of the species from the eastern Indian Ocean ( Fig. 2 ) .

Epigonus lifouensis belongs to the E. pandionis group of Okamoto and Motomura (2013) defined as lacking an opercular spine, more than 45 pored lateral-line scales to the end of the hypural and dorsal-fin rays VII-I, 10. The species group comprises 9 species, including E. lifouensis : E. cavaticus Ida et al., 2007 ; E. denticulatus Dieuzeide, 1950 ; E. elongatus Parin and Abramov, 1986 ; E. fragilis ( Jordan and Jordan, 1922); E. marisrubri Krupp et al., 2009 ; E. pandionis (Goode and Bean, 1881) ; E. parini Abramov, 1987 ; and E. tuberculatus Okamoto and Motomura, 2013 .

Characters of the present Indonesian specimens agree with the characteristics of the two types and another specimen from the western Pacific of E. lifouensis reported in previous studies, with the exception of the gill rakers for which the Indonesian specimens had 26–28 (vs. 24–25 in Okamoto and Motomura 2013; Okamoto et al. 2018). Although the gill raker counts of E. lifouensis reported in previous studies are based on a small number of the specimens (totall 3 specimens), I regard the difference as an intraspecific variation in the populations between the western Pacific and eastern Indian Oceans, with no overlap.

Figures

Fig. 1. Epigonus lifouensis, HUMZ 191539, 150.4mm SL, from off Sumatra, Indonesia.

Fig. 2. Distributional records of Epigonus lifouensis (stars) and E. pectinifer (circle) in the eastern Indian Ocean.