Epigonus draco Okamoto 2015

Okamoto, Makoto, Chen, Wei-Jen & Shinohara, Gento, 2018, Epigonus okamotoi (Perciformes: Epigonidae), a junior synonym of E. draco, with new distributional records for E. atherinoides and E. lifouensis in the West Pacific, Zootaxa 4476 (1), pp. 141-150 : 142-145

Epigonus draco Okamoto 2015

English name: Dragon DeepWater Cardinalfish

( Fig.1 ; Table 1)

Epigonus draco OKAmOTO, 2015 : 121, fIg. 1 (ORIgInAl dEscRIPTIOn, TyPE lOcAlITy: SOlOmOn IslAnds [07°43′34″S, 158°29′24″E; 08°41′16″S, 157°41′27″E], WEsTERn SOuTH PAcIfIc [cOllEcTEd duRIng THE SALOMON 2 ExPEdITIOn undER THE TDSB]); OKAmOTO 2016: 184, fIg. 6 (PHOTOgRAPH And nOTEs, SOcIETy IslAnds).

Epigonus ctenolepis (nOT Of MOcHIzuKI & SHIRAKIHARA, 1983): IWAmOTO & McCOsKER 2014: 291, fIg. 122 (cOlOR PHOTOgRAPH And nOTEs, bETWEEn LuzOn And MIndORO, PHIlIPPInEs).

Epigonus okamotoi FRIcKE, 2017 : 117, fIg. 1–4 (ORIgInAl dEscRIPTIOn, TyPE lOcAlITy: SOlOmOn SEA, PAPuA NEW GuInEA, WEsT NEW BRITAIn PROvIncE, Off sOuTHWEsTERn NEW BRITAIn, AInTO BAy [06°06′04.7988″S, 149°12′12.5136″E; 06°07′38.3376″S, 149°12′06.4152″E], WEsTERn SOuTH PAcIfIc [cOllEcTEd duRIng THE MADEEP ExPEdITIOn undER THE TDSB]).

Material examined. 12 specimens, 87.1–160.1 mm SL. Papua NeW Guinea : NTUM 11869 (tissue voucher: PNG 2315), 105.2 mm SL, 06°07′S, 149°13′E, 570 m depth, St. CP 4332, 6 May 2014, R/ V Alis, MADEEP Expedition ; NTUM 12701 (tissue voucher: PNG 2250), holotype of E. okamotoi , 158.8 mm SL, 06°06′04.7988″S, 149°12′12.5136″E; 06°07′38.3376″S, 149°12′06.4152″E, 315–624 m depth, St. CP 4330, 6 May 2014, R/ V Alis, MADEEP Expedition ; NTUM 13035 (tissue voucher: PNG0963 ), 103.7 mm SL, 05°25′S, 145°56′E, 500–870 m depth, St. CP4021, 13 December 2012, R/V ALIS, PAPUA NIUGINI Expedition. Philippines : CAS 235796 , paratype, 160.1 mm SL, 13°36′7″N, 120°23′2″E, betWeen LuZon and Mindoro, 541–636 m depth, 1 June 2011. Society Islands : MNHN 2014-0217 , 104.7 mm SL, 16°41′11″S, 151°25′30″W, Raiatea island , 638–700 m depth, St. CP 3438, 16 October 2009, R/V ALIS, TARASOC Expedition ; MNHN 2014-0871 , 87.1 mm SL, 16°46′31″S, 151°22′41″W, Raiatea island , 573–611 m depth, St. CP 3458, 18 October 2009, R/ V Alis, TARASOC Expedition. Solomon Islands : MNHN 2006-0589, holotype, 127.4 mm SL, 07°43′34″S, 158°29′24″E, 391–623 m depth, St. CP2206, 25 October 2004, R/V Alis, SALOMON 2 Expedition; MNHN 2006-0684 , paratype, 88.8 mm SL, same data as holotype ; MNHN 2006-0063 , 2 paratypes, 110.0–145.0 mm SL, 08°41′16″S, 157°41′27″E, 786 m depth, St. CP 2277, 5 November 2004, R/V Alis, SALOMON 2 Expedition. Vanuatu : MNHN 2012-0836 , paratype, 128.1 mm SL, 15°41′31″S, 167°01′19″E, West of Malo Island , 481 m depth, St. AT 9, 17 September 2006, R/ V Alis, SANTO 0 6 Expedition.

Diagnosis. A species of Epigonus With the folloWing combination of characters: dorsal-fin rays VII–I, 10;

pectoral-fin rays 19–20; total gill rakers 22–23; pyloric caeca 7–10; pored lateral-line scales 47–49 + 3–4; scales beloW lateral line 9; vertebrae 10 + 15; opercular spine present; maxillary mustache-like processes absent; ribs absent on last abdominal vertebra; uppermost margin of pectoral-fin base loWer than horiZontal line through center of eye; proximal radial of first anal-fin pterygiophore slender; and mouth cavity black.

Distribution. KnoWn from the Philippines ( IWamoto & McCosker 2014), Papua NeW Guinea (Fricke 2017; this study), Solomon Islands, Vanuatu ( Okamoto 2015), and Society Islands (Okamoto 2016), at depths of 391–870 m ( Fig. 2 ).

Synonymy. Fricke (2017) referred E. okamotoi to the E. constanciae group (sensu Okamoto 2012) based on the presence of a pungent opercular spine. According to Okamoto (2016), this species group comprises 19 species besides E. okamotoi : E. affinis Parin & Abramov 1986 ; E. atherinoides ( Gilbert 1905) ; E. chilensis Okamoto 2012 ; E. constanciae (Giglioli 1 880); E. crassicaudus de Buen 1959 ; E. ctenolepis MochiZuki & Shirakihara 1983 ; E. draco Okamoto 2015 ; E. elegans Parin & Abramov 1986 ; E. heracleus Parin & Abramov 1986 ; E. lenimen (Whitley 1935) ; E. machaera Okamoto 2012 ; E. marimonticolus Parin & Abramov 1986 ; E. mayeri Okamoto 2011 ; E. megalops (Smith & Radcliffe in Radcliffe 1912) ; E. occidentalis Goode & Bean 1896 ; E. pectinifer Mayer 1974 ; E. robustus (Barnard 1927) ; E. thai Prokofiev & BussaraWit in Parin et al. 2012 ; and E. waltersensis Parin & Abramov 1986 . Fricke (2017) stated that E. okamotoi is distinguishable from similar species of this group in having a combination of the folloWing characters: dorsal-fin rays VII–I, 9; pectoral-fin rays 15; gill rakers 22; pyloric caeca 4; pored lateral-line scales 47 + 4; scales beloW lateral line 8; vertebrae 10 + 15; opercular spine present; maxillary mustache-like process absent; ribs absent on last abdominal vertebra; upper margin of pectoralfin base on level of upper margin of pupil; proximal radial of first anal-fin pterygiophore slender; mouth cavity light grey. HoWever, re-examination of the holotype of E. okamotoi revealed that the holotype has dorsal-fin ray VII–I, 10, pectoral-fin rays 20, and scales beloW lateral line 9. Additionally, the position of the upper margin of pectoral-fin base of the holotype of E. okamotoi in fresh condition is loWer than a horiZontal line through the center of eye (Fricke 2017: fig. 3). The position of the pectoral fin of species of Epigonus slightly change after fixation oWing to the shrinkage of the body. These characters and other meristic characters except for pyloric caeca (not confirmed to avoid damaging the specimen) of the holotype of E. okamotoi correspond to that of E. draco . Fricke (2017) noted that E. okamotoi differs from E. draco in the orbital diameter, postorbital length, snout length, preanus length, preanal-fin length, and length of third spine of first dorsal-fin. HoWever, there are no clear differences in the morphometric characters betWeen this holotype and the examined specimens of E. draco , including tWo additional specimens of the species from Papua NeW Guinea ( Table 1). Further comparison of DNA sequences at the COI locus for the samples from E. draco and E. “ okamotoi ” demonstrated that the genetic distance (p- distance) betWeen the tWo “species” Was negligible (0 – 0.00156) ( Table 2). The p- distances betWeen E. draco and E. atherinoides , both of the E. constanciae species group, Was substantially higher at 0.09390 and 0.09546 ( Table 2). Therefore, the holotype of E. okamotoi is considered to be a specimen of E. draco , and the former nominal species is reduced to a junior synonym of E. draco .

Remarks. We found additional specimens of E. draco , collected in Papua NeW Guinea, at the National TaiWan University Museums (NTUM). These specimens represent the first record of this species from this locality. Epigonus draco is distributed on continental slopes in the Western and central tropical Pacific, at depths greater than 315 m.

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Figures

FIGURE 1. Epigonus draco. A, HOlOTyPE Of E. okamotoi (NTUM 12701, 158.8 mm SL, PREsERvEd sPEcImEn, PAPuA NEW GuInEA); B, HOlOTyPE Of E. draco (MNHN 2006-0589, 127.4 mm SL, PREsERvEd sPEcImEn, SOlOmOn IslAnds); C, E. draco (NTUM 11869, 105.2 mm SL, fREsH sPEcImEn, PAPuA NEW GuInEA).

FIGURE 2. DIsTRIbuTIOnAl REcORds Of Epigonus draco (OPEn TRIAnglEs = PREvIOus sTudIEs And AddITIOnAl sPEcImEns In PREsEnT sTudy; sOlId TRIAnglE = TyPE lOcAlITy Of E. okamotoi), E. atherinoides (OPEn sTARs = PREvIOus sTudIEs; sOlId sTARs = PREsEnT sTudy), And E. lifouensis (OPEn cIRclE = TyPE lOcAlITy; sOlId cIRclE = PREsEnT sTudy) In WEsTERn PAcIfIc OcEAn.