New distributional records of three deepwater cardinalfishes Epigonus angustifrons, E. denticulatus, and E. exodon (Perciformes: Epigonidae) in the South Indian Ocean Author Okamoto, Makoto Author Chen, Wei-Jen Author Motomura, Hiroyuki text Cybium 2020 44 2 165 168 http://dx.doi.org/10.26028/cybium/2020-442-008 journal article 10.26028/cybium/2020-442-008 2101-0315 12711652 Epigonus angustifrons Abramov & Manilo, 1987 ( Fig. 1 ; Tab. I ) Material examined Two specimens : CSIRO H 5408-03 ( 189.7 mm SL, female), CSIRO H 5408-04 ( 210.3 mm SL, female), 34°56.87’S , 81°11.92’E , St. Paul Seamount , central South Indian Ocean , 430-595 m depth , 1 May 1997 , demersal trawl, FRV Austral Leader . Diagnosis Dorsal-fin rays VII-I-I, 10-11; pectoral-fin rays 19-21; total gill rakers 33-36; vertebrae 10 + 15; pyloric caeca 21-24; pored lateral-line scales 47-50 + 3-5; scales below lateral line 11; opercular spine absent; maxillary mustache-like processes absent; ribs on last abdominal vertebra present; tongue toothless; oral cavity black; body depth 18.1-19.1% SL. Distribution Western and central South Indian Ocean ( Okamoto and Gon, 2018 ; present study; Fig. 2 ) and eastern South Atlantic ( Okamoto and Gon, 2018 ). Figure 1. – Epigonus angustifrons , CSIRO H 5408-04, 210.3 mm SL, central South Indian Ocean. (1) Marine Fisheries Research and Development Center, Fisheries Research Agency, 15F Queen’s Tower B, 2-3-3 Minatomirai, Nishi-ku, Yokohama, Kanagawa 220-6115, Japan . [epigonidae@gmail.com] (2) Institute of Oceanography, National Taiwan University, No. 1 Sec. 4 Roosevelt Rd. Taipei 10617, Taiwan . [wjchen.actinops@gmail. com] (3) The Kagoshima University Museum, 1-21-30 Korimoto, Kagoshima 890-0065, Japan . [motomura@kaum.kagoshima-u.ac.jp] * Corresponding author Table I. – Meristic counts and measurements (% of standard length) of Epigonus angustifrons , E. denticulatus , and E. exodon specimens examined in this study.

E. angustifrons	E. denticulatus	E. exodon
Standard length (mm)	189.7-210.3	120.2-138.6	131.0
Dorsal-fin rays	VII-I-I, 10	VII-I, 10	VII-I, 10
Anal-fin rays	II, 9	II, 9	II, 9
Pectoral-fin rays	20	18-19	16
Pored lateral-line scales	46-47 + 5	45-46 + 3-4	40 + 5
Scales above lateral line	4	3	3
Scales below lateral line	11	10	9
Gill rakers	11 + 23 = 34	10 + 24 = 34	7 + 21 = 28
Pyloric caeca	21-24	10	10
Vertebrae	10 + 15	10 + 15	10 + 15
Head length	32.6	33.9-35.0	31.5
Head width	18.2-18.3	16.1-17.7	16.6
Head height	15.8-17.0	16.7-16.8	16.0
Body depth	18.7-19.0	19.2-19.4	26.4
Body width	17.2-18.7	14.5-16.0	14.7
Caudal-peduncle depth	8.7-8.8	8.4-9.0	11.5
Caudal-peduncle length	26.9-28.8	28.1-30.4	28.0
Orbital diameter	12.2-13.4	14.4-14.8	13.2
Interorbital width	8.5-8.9	9.6-10.4	7.6
Postorbital length	12.8-13.6	12.4-14.2	12.3
Upper-jaw length	14.5-15.4	14.6-15.5	13.4
Lower-jaw length	17.0-17.7	16.9-17.4	14.7
Snout length	7.9-8.0	7.1-7.4	8.1
Pre-1st dorsal-fin length	38.1-38.5	37.4-38.1	34.1
Pre-2nd dorsal-fin length	60.2-60.9	57.2-58.3	54.0
Prepectoral-fin length	33.1-33.9	33.2-34.5	33.7
Prepelvic-fin length	33.3-33.7	34.5-34.9	40.7
Preanus length	58.9-60.8	53.9-56.6	60.0
Preanal-fin length	63.5-65.7	61.0-62.5	65.2
1st spine length on 1st dorsal fin	5.9-7.2	2.8	Tip broken
2nd spine length on 1st dorsal fin	Tip broken	11.8	16.2
3rd spine length on 1st dorsal fin	Tip broken	12.9	16.6
2nd dorsal-fin spine length	5.1-5.6	6.2	14.6
1st anal-fin spine length	2.1-2.5	1.9-2.0	2.7
2nd anal-fin spine length	5.3-6.3	5.9-6.2	15.4
Pelvic-fin spine length	Tip broken	7.9-8.9	15.9
1st dorsal-fin base	10.4-11.3	10.3-10.5	12.3
2nd dorsal-fin base	10.7-11.3	9.1-9.3	12.2
Anal-fin base	9.3-9.4	8.6-9.6	10.5
Pectoral-fin length	20.9-21.1	16.9-17.9	18.8
Pelvic-fin length	17.2-18.4	14.1-14.7	20.9

Figure 2. – Collection localities of Epigonus angustifrons (present study: Z; Okamoto and Gon, 2018 :), E. denticulatus (present study: Δ; Okamoto and Gon, 2018 : A), and E. exodon (present study: C; Okamoto and Motomura, 2012 : l ) in the central and western South Indian Ocean. Remarks The present specimens represent the first confirmed record of this species from the central South Indian Ocean. There are no clear differences in the meristic and morphometric characters between the present and previously recorded specimens. Epigonus angustifrons has an isolated dorsal-fin spine between the first and second dorsal fins and a character that makes it a member of the E. telescopus group by having the isolated dorsal-fin ray ( Abramov, 1992 ; Okamoto and Gon, 2018 ). The isolated dorsal-fin spine of the species is rarely reduced, becoming difficult to discern (e.g. CSIRO H 5408-04). In the Indian Ocean, E. angustifrons is similar to E. denticulatus in having a slender body and more than 30 gill rakers, but differs in having a black oral cavity.