Neoepinnula minetomai Nakayama, Kimura et Endo, 2014

Ho, Hsuan-Ching, Cheng, Yu-Nung, Su, Yo, Hsu, Yu-Chieh & Shyu, Jeng-Feng, 2025, New record of the large-eyed sackfish, Neoepinnula minetomai (Actinopterygii, Scombriformes, Gempylidae), from western Taiwan, Acta Ichthyologica et Piscatoria 55, pp. 341-347 : 341-347

Neoepinnula minetomai Nakayama, Kimura et Endo, 2014

New Taiwanese name: 大眼新帶鰆 (Figs 1 , 2 ; Table 2 )

Neoepinnula minetomai Nakayama, Kimura et Endo, 2014. — Nakayama et al. (2014): 322, figs. 1–2 (type locality: southeast of Kuchierabu-jima Island, Kagoshima, East China Sea, ca. 380–420 m).

Description of NMMB-P 42779 .

Fin elements: dorsal fin XVI, I, 20; pectoral fin 15 (first ray unsegmented); pelvic fin I, 5; anal fin III, 20; caudal fin 9 + 8 (principal rays). Vertebrae: 16 precaudal + 16 caudal = 32.

Body relatively short and relatively deep, moderately compressed. Deepest at pelvic-fin origin, its depth 3.5 in SL; width at pectoral-fin base 9.3 in SL or 2.6 in BD. Dorsal profile curved dorsally and ventral profile curved ventrally, with spinous dorsal-fin base straight.

Head large, 3.2 in SL; predorsal profile sloping downward and gradually depressed over interorbital space, then continue to snout tip. Snout triangular, relatively short, long triangular in dorsal view, its length 2.8 in HL. Orbit large, circular, fleshy diameter smaller than snout length, its diameter 3.4 in HL. Interorbital space broad, slightly smaller than eye diameter, its fleshy width 3.5 in HL, bony width 4.9 in HL.

Dorsal-fin origin slightly behind upper end of gill slit, and slightly before vertical of posterior margin of gill cover and very slightly behind turning point of upper lateral line. First (spinous) dorsal fin with long base, its 3 rd to 7 th spines longest, subequal in length. Second dorsal fin originating above anal-fin origin, short-based with its base length 2.8 in that of first dorsal fin; its spine relatively short, length about 2.7 in height of second dorsal fin, closely adjoined to first soft ray.

Pectoral fin inserted below midlateral axis of body, upper end of fin base about same vertical of posterior margin of operculum and extending posteriorly to vertical through base of ninth spine of dorsal fin; upper rays longer, gradually shorter ventrally. Pelvic fin well developed, inserted below base between 5 and 6 dorsal-fin spines. Anal fin similar to and opposite second dorsal fin, anterior two spines small and free; third spine closely adhered to first soft ray, length about 3.2 in height of anal fin. No finlets on caudal peduncle. Caudal fin deeply forked, upper lobe slightly longer than lower lobe, length of upper lobe 1.2 in HL and lower lobe 1.3 in HL; middle fin short, 3.6 in HL.

Mouth terminal, not protrusible, lacking dermal processes on anterior tips; lower jaw slightly extending beyond upper jaw; posterior end of maxilla extending to vertical through anterior margin of eye pupil, about 1 / 4 eye diameter behind anterior eye margin. Preopercle relatively small, its hind margin slightly inclined from vertical; posteroventral corner of preopercle forming a broadly rounded angle; preopercular spines absent. Gill slit broad, extending forward to below corner of mouth. Gill rakers not available (removed before being purchased). Two nostrils, well separated, space between two nostrils about 3.8 in eye diameter; anterior small, somewhat tubular, directed anteriorly; posterior forming elongated slit, located midway between anterior nostril and anterior rim of orbit. Anus distinctly before anal-fin origin, space 3.7 in HL. No keels on caudal peduncle.

Three large, fixed fangs on roof of oral cavity anteriorly, plus two small, newly generated backward-depressed teeth. Premaxillary with single row of ca. 27 (some lost but with hole) teeth compressed laterally, slightly recurved, middle teeth largest. Vomer with small conical tooth on either side. Single row of ca. 17 small teeth on palatines. Dentary with ca. 11 (some lost but with hole) teeth, much larger than those on upper jaw, and increasing in height posteriorly.

Body fully covered with small, deciduous, cycloid scales. Second dorsal, anal, and caudal fins mostly covered with small scales; other fins completely naked. Head fully scaled except for lips, tips of snout and lower jaw, and gular and branchiostegal membranes (partly damaged due to dissection).

Lateral line forming single canal, running along dorsal profile (mostly dorsal-fin base), posterior margin of head and pectoral-fin base (mostly pectoral girdle), and lower margin of belly and anal-fin base; upper and lower portions run through lateral side of caudal peduncle, upper branch ended at posterior margin of hypural plate, and lower branch extending into caudal-fin base for short distance.

Lateral-line scales distinctly larger than neighboring body scales, those on upper portion with short canal opening upward and backward on upper margin of each scale, on anterior portion (vertical row) opening backward and downward on posterior margin of each scales, and on lower portion opening downward and backward on lower margin of each scale. Lateral-line scales mostly remain, 103 on upper portion (horizontal row), 39 on anterior portion (vertical row) and 111 on lower portion (horizontal row).

Otolith morphology.

Sagittal otolith (Fig. 2 ; 10.12 and 10.21 mm otolith length in left and right otolith, respectively) elliptical, with anterior rim pointed and posterior rim blunt; length / height ratio 1.72 (left otolith) and 1.77 (right otolith). Both dorsal and ventral rims curved. Anterior rim with deep notch and forming large and pointed rostrum. Antirostrum truncated and very short. All margins crenulated or lobated, with small fenestrations on ventral area. Otolith thin, with distal margin slightly convex and proximal margin slightly concave. Sulcus centrally positioned, with ostium deeper than cauda; ostium and cauda slightly differentiated. Ostium elongated and cauda rather oval. Crista superior mostly evident anteriorly near notch; crista inferior indistinct. Colliculum indistinct, slightly posterior to middle of sulcus. Dorsal depression shallow.

Coloration.

When fresh, body silvery gray in general, with dorsum and gill cover slightly darker; all fins dusky, with black margin on first dorsal fin and distal half of middle caudal-fin ray’s pale. When preserved, body slightly paler and with lost silvery shining.

Remarks.

The short body and lateral-line morphology identify the species to Neoepinnula and the large eye and lacking enlarge canines on lower jaw can be easily recognized as N. minetomai . Our specimen ( 322 mm SL) is about the same size of the holotype ( 327 mm SL) and slightly larger than the paratype ( 286 mm SL). Compared to the data in original description (Table 1 ), our specimen has a slightly smaller head (31.2 %, vs. 33.4 % – 34.8 % SL), shorter predorsal length (29.6 %, vs. 31.6 % – 32.6 % SL), slightly longer preanal length (72.4 %, vs. 70.2 % – 71.5 % SL), and a slightly smaller eye (9.2 %, vs. 10.6 % – 10.9 % SL). These can be treated as individual variations.

In the presently reported study, in addition to Neoepinnula minetomai , we illustrated the following species: Epinnula rex Ho, Motomura, Hata et Chiang, 2022 (Fig. 3 A ); Gempylus serpens Cuvier, 1829 (Fig. 3 B ); Lepidocybium flavobrunneum (Smith, 1843) (Fig. 3 C ); Nealotus tripes Johnson, 1865 (Fig. 3 D ); Neoepinnula orientalis (Gilchrist et von Bonde, 1924) (Fig. 3 E ); Promethichthys prometheus (Cuvier, 1832) (Fig. 4 A ); Rexea bengalensis (Alcock, 1894) (Fig. 4 B ); Rexea prometheoides (Bleeker, 1856) (Fig. 4 C ); Ruvettus pretiosus Cocco, 1833 (Fig. 4 D ); Thyrsitoides marleyi Fowler, 1929 (Fig. 4 E ).

In addition to the original description, we added information of the numbers and shape of the lateral-line scales, and the otolith morphology, which provide further diagnostic features.

Thus far, only two types and the additional Taiwanese specimen are available which may suggest that this is a very rare species compared to it congeners. All three specimens were obtained from off small islands which may suggest that this is an insular species in the western Pacific Ocean.

Figures

Figure 1. Fresh (defrosted) specimen of Neoepinnula minetomai, NMMB-P 42779, 322 mm SL.

Figure 2. Sagittal otoliths of Neoepinnula minetomai, from NMMB-P 42779, 322 mm SL. A Left otolith B, C Right otolith. A, C Proximal views B Ventral view Scale bar = 5 mm.

Figure 3. Fresh specimens of gempylids of Taiwan. A Epinnula rex, NMMB-P 42663, 313 mm SL. B Gempylus serpens, NMMB-P 42664, 896 mm SL. C Lepidocybium flavobrunneum, NMMB-P 42665, 570 mm SL. D Nealotus tripes, NMMB-P 42666, 135.9 mm SL. E Neoepinnula orientalis, NMMB-P 42667, 153 mm SL.

Figure 4. Fresh specimens of gempylids of Taiwan. A Promethichthys prometheus, NMMB-P 42668, 604 mm SL. B Rexea bengalensis, NMMB-P 42669, 142.8 mm SL. C Rexea prometheoides, NMMB-P 42670, 285 mm SL. D Ruvettus pretiosus, NMMB-P 42671, 702 mm SL. E Thyrsitoides marleyi, NMMB-P 42672, 965 mm SL.