Spectrunculus grandis

Uiblein, Franz, Møller, Peter R. & Nielsen, Jørgen G., 2023, The Systematics of the Ophidiid Genus Spectrunculus (Teleostei, Ophidiiformes) Revisited with Description of a New Species and Resurrection of S. radcliffei, Ichthyology & Herpetology 111 (3), pp. 467-485 : 477-481

Origin of dorsal fin above vertebra 7–9, well in front of distal tip of pectoral fin. Pelvic fins with two rays reaching about halfway from base to anal-fin origin. Pectoral fins on lower half of body, rather short, 9.6–11 times in SL, and rather wide at fin base, the width 23–27 times in SL.

Otolith ( Fig. 3 ) oval to elongate (length to height ratio 1.34–2.10), with pointed posterior tip. Anterior tip rounded. Sulcus moderately long, 43–72% of otolith length, with separate colliculi and located at the center of inner face. Ostium vertically enlarged, its width 22–30% of sulcus length and 31–40% of ostium length in fish of 187 mm SL and larger; ostium width 59% of ostium length in the 110 mm juvenile.

Coloration.— Fresh or recently caught fish mostly entirely dark brown. Among the 42 specimens collected during the MAR-ECO expedition in the North Atlantic in 2004, 37 showed uniformly dark-brown colored body, head, and fins; one larger specimen (445 mm SL) had a speckled color pattern with dark dots or blotches on pale background on head, body, and fins; four of the five smallest specimens (187–253 mm SL) had light brown body and head color with ventral parts of head and belly pale bluish gray. Longtime preserved specimens including HT are entirely light brown .

Distribution.— This species is distributed in the Atlantic and East Pacific Ocean (1580 to 4255 m depth).

Remarks.— Among the specimens that could be sexed were ten males and 27 females. No sexual dimorphism could be found in any of the meristic and morphometric characters including otoliths (see also Uiblein et al., 2008). Slight positive allometry in jaw length and negative allometry in orbit length was found ( Fig. 4 ). Orbit in head length in the East Pacific population is slightly shorter than in the Atlantic. Otolith length showed negative allometry, while ostium and sulcus shape did not when the entire size range is considered ( Fig. 4 ). However, the smallest specimen showed a slightly wider and shorter ostium which— when combined—indicate an early life-history shift in otolith form (i.e., from small-sized juveniles to larger-sized subadults and adults). No regional variation in meristic characters could be detected.

Spectrunculus grandis (G unther €, 1877)

Figures 1–4 , Tables 2, 3, 6

Sirembo grandis G unther €, 1877 (type locality: Northwest Pacific , E of Central Japan, 34837 0 N, 140832 0 E) .

Spectrunculus grandis : Hubbs and Follett, 1978; in part: Nielsen and Hureau, 1980; Uiblein et al., 2008.

Holotype.— BMNH 1887, 675 mm SL (pale; described as brown in original description by G unther €, 1877), Northwest Pacific , E of Central Japan, 34837 0 N, 140832 0 E, R / V Challenger, sta. 237, 3431 m depth, 17 June 1875.

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Non-type material.— SW Pacific (n ¼ 3): CSIRO H-6036.01, male, 450 mm SL (pale), 3283 0 S, 159852 0 E to 3282 0 S, 159851 0 E, NORFANZ cruise, R / V TANGAROA , station # 0308/071, 1920– 1934 m depth, 24 May 2003 ; LACM 43564- 1, 200 mm SL (light brown), 42811 0 S, 175811 0 E, 2602–2619 m depth, 20 September 1966 ; NMNZ P.041204, female, 840 mm SL (dark), 58836 0 S, 161823 0 E, 1496–1638 m depth, 19 August 2004 .

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NE Pacific (n ¼ 3): CAS-ICH 25724, male, 1270 mm SL (light brown), California, 40 miles west southwest of the Farallon Islands , 37830 0 N, 13284 0 W, surface, above ca. 3000 m depth; CAS-ICH 90121 , 1283 mm SL (dark), California , off Trinidad Head, 41850 0 N, 125810 0 W, surface, above ca. 2500 m depth, 16 September 1996; OSUO 11789, 370 mm SL (light brown), 44841.8 0 N, 127822.7 0 W, 3021 m depth, 12 June 1974.

Diagnosis.— Number of dorsal-fin rays 135–137, anal-fin rays 101–105, total vertebrae 77–80, pre-anal length 47–55% in SL, pelvic- to anal-fin origin 32–36% in SL, orbit length 9.3–14 in % HL, otolith ostium width 24–29 in % sulcus length and 35– 39 in % ostium length; maximum size to 130 cm SL.

Description.— The most important meristic and morphometric characters as well as the otolith characters are shown in Tables 2, 3, and 6. Body elongate, laterally compressed, tapering towards tail. Pectoral-fin depth in HT 7.2 times in SL, tail length 1.80–1.88 times in SL, and preanal length 1.04–1.14 times in tail length in HT and two non-types. Head length 4.9–5.9 in SL and 2.22–2.89 in preanal length; head depth through eye 8.57 times in SL. Orbit circular, shorter than snout, 1.98–3.27 times in snout length. Anterior gill arch with 7–10 long and 11–19 rudimentary rakers. Pseudobranchial filaments 1–2.

Origin of dorsal fin above vertebrae 9–10, well in front of distal tip of pectoral fin. Pelvic fins with two rays in each reaching about 1/4 to 1/3 from its base to anal-fin origin. Pectoral fins on lower half of body, rather short, 10–12 times in SL, and moderately wide at fin base, the width 17–19 times in SL.

Otolith ( Fig. 3C–E ) oval to slightly elongated (length to height ratio 1.20–1.67), posteriorly flattened or with only a weakly pointed tip. Variably formed anteriorly, no pointed tip. Sulcus long, 49–61% of otolith length with separate colliculi and located at the center or slightly dorsally of inner face. Ostium width 24–29% of sulcus length and 35–39% of ostium length.

Coloration.— Two specimens collected in the Southwest Pacific in 2000 and 2003 (510–1060 mm SL) both showed light brown body and head color when fresh (the smaller specimen slightly paler and pale grayish from below eye to belly) and were found to be pale after preservation, the unpaired fins still being slightly darker. A large Northeast Pacific specimen (1270 mm SL) had pinkish orange color when fresh ( Hubbs and Follett, 1978). The largest specimen studied from the same area collected drifting at the surface in 1996 was still entirely dark brown when studied in 2019. Long-term preserved HT (collected in 1877) is pale, creamy whitish ( Fig. 1 ).

Distribution.— This species is distributed in the West to Northeast Pacific (1496 to 3431 m depth).

Remarks.— Otolith length appears to follow the negative allometric trend as in the other three species of Spectrunculus , and the two largest S. grandis have particularly short pelvic fins ( Fig. 4 ). However, too few specimens were available for study to allow us to investigate intraspecific variation (sex-, size-, or population-related) more closely. Small-sized specimens (, 200 mm SL) not known; the smallest specimen studied is 200 mm SL.

Figures

FIG. 3. Images of otoliths of Spectrunculus. (A) S. stenostio, ZMUB 18480, 670 mm SL, N Atlantic (F. Uiblein); (B) S. crassus, ZMUB 18464, 575 mm SL, N Atlantic (F. Uiblein); (C–E) S. grandis: (C) HT, BMNH 1887, 675 mm SL, NW Pacific (CT scan, B. Clark); (D) CAS 25724, 1270 mm SL, NE Pacific (F. Uiblein); (E) LACM 43564, 200 mm SL, SW Pacific (M. A. Krag); (F–H) S. radcliffei: (F) ZMUC P77704, 192 mm, S Atlantic (M. A. Krag); (G) ZMUC P2397445, 945 mm SL, NW Pacific (from left head side, shown sidereversed; M. A. Krag); (H) ZMUC P2397724, 1020 mm SL, NW Pacific (M. A. Krag). All otoliths from right side of head if not otherwise indicated. Dotted lines with arrows indicate the approximate measurement positions for ostium width (left side of figure) and sulcus length (right side of figure). Length of black or white scale bars is 5 mm.

FIG. 4. Relationships between morphological characters in the four species of Spectrunculus.

FIG. 1. (A–C) Spectrunculus stenostio: (A) HT, ZMUB 18493, 825 mm SL, N Atlantic (F. Uiblein); (B) SAIAB 11892, 706 mm SL, S Indian Ocean (F. Uiblein); (C) NMNZ P.033111, 1030 mm SL, SW Pacific (P. R. Møller). (D–F) S. crassus: (D) ZMUB 18355, 187 mm SL, N Atlantic (MAR-ECO cruise); (E) HT, MNHN 1886-0552, 284 mm SL, N Atlantic (J. Pfliger); (F) ZMUB 18463, 500 mm SL, N Atlantic (MAR-ECO cruise); (G–I) S. grandis: (G) HT, BMNH 1887, 675 mm SL (F. Uiblein); (H) NMNZ P.041204, 840 mm SL, SW Pacific (P. R. Møller); (I) CAS 25724, 1270 mm SL, NE Pacific (Moulin Studios, San Francisco, used with permission); (J–M) S. radcliffei: (J) HT (postlarva), FMNH 57123, 56 mm SL, NW Pacific (FMNH Zoological Collections, used with permission); (K) SAM 47240, 541 mm SL, S Atlantic (F. Uiblein); (L) ZMUC P2397445, 945 mm SL, NW Pacific (M. A. Krag); (M) ZMUC P2397724, 1020 mm SL, NW Pacific (M. A. Krag). Length of black or white scale bars is 5 cm.

FIG. 2. Distribution map showing the occurrence of studied specimens of the genus Spectrunculus. For areas with multiple occurrences, numbers are added to the respective symbols. Type localities are indicated by filled symbols.