Spectrunculus radcliffei

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 : 481-484

Spectrunculus radcliffei Jordan and Thompson, 1914

Figures 1–4 , Tables 2, 3, 5, 7

Spectrunculus radcliffei Jordan and Thompson, 1914 (type locality: NW Pacific, Japan, 35810 0 N, 139837 0 E).

Spectrunculus grandis non (G unther €, 1877), in part: Nielsen and Hureau, 1980; Uiblein et al., 2008.

Holotype.— FMNH 57123 , postlarva (pale; described as translucent in original description by Jordan and Thompson, 1914), 56 mm SL, NW Pacific , Japan, Misaki, 35810 0 N, 139837 0 E.

Non-type material.— S Atlantic (n ¼ 6): CAS-ICH 40233, female, 378 mm SL (light brown), off Cape of Good Hope, 35807 0 S, 18825.6 0 E, ca. 1000 m depth; SAIAB 47240, 541 mm SL (dark), off Cape Columbine , Western Cape, 32822 0 S, 16809 0 E, 1150 m depth, trawl, 14 January 1995 ; SAM F023413 , 188 mm SL (pale), 33852 0 S 16851 0 E , RV Africana II, 2440 m depth, 9 December 1959 ; SAM F027093 , 190 mm SL (pale), 33849 0 S, 16830 0 E , RV Africana II, 2743 m depth, 27 August 1959 ; ZMUC P 77702, 196 mm SL (light brown), 33836 0 S, 16815 0 E, R / V AFRICANA II , sta. 191, 3080 m depth, beam trawl, 24 August 1959 ; ZMUC P 77704, 192 mm SL (light brown), 34846 0 S, 16842 0 E, R / V AFRICANA II , sta. 316, 3360 m depth, beam trawl, 8 December 1959 .

S Indian Ocean: MNHN OTO 354-49 (only otolith and photo of freshly collected fish retained), 910 mm SL (light brown), Kerguelen, 50850 0 S, 69853.8 0 E, 1769 m depth, F/ V Albius , longline, 20 September 2012 .

NW Pacific (n ¼ 3) : ZMUC P2397424 , male, 1020 mm SL (pale), 2500 m depth , ZMUC P2397444 , female, 950 mm SL (light brown) , ZMUC P2397445 , male, 945 mm SL (light brown), 2000 m depth , Suruga Bay , Central Japan, 348N, 1388E, caught in 2020 .

SW Pacific (n ¼ 2): NMNZ P.041951, male, 332 mm SL (pale), 34831.5 0 S, 166821 0 E, 2930 m depth, September 1982; NMV A25135.002, female, 423 mm SL (pale), 3283.98 0 S, 159852.8 0 E to 3282.26 0 S, 159851.11 0 E, NORFANZ cruise, R / V TANGAROA , sta. TAN 0308/071, 1920–1934 m depth, 24 May 2003.

NE Pacific (n ¼ 11): OSUO 11722 , 88 mm SL (dark), off Oregon Coast, 44848.8 0 N, 125836.5 0 W, ca. 2800 m depth, 8 March 1972 ; OSUO 11738 , 94 mm SL (light brown), 45856.4 0 N, 127839.1 0 W, 2763 m depth, 13 March 1973 ; CAS-ICH 246805, male, 478 mm SL (light brown), 45818 0 42 00 N, 126834 0 24 00 W, R / V YAQUINA, beam trawl, 2750 m depth, 2 December 1974 ; CAS-ICH 32364, male, 495 mm SL (light brown), off Oregon, 44857 0 18 00 N, 126837 0 18 00 W to 44858 0 0 00 N, 126842 0 42 00 W, 2850 m depth, beam trawl; CAS-ICH 33083, male, 665 mm SL (light brown), female, 536 mm SL (dark), off Oregon, near Cascadia Channel, 45822 0 24 00 N, 127827 0 48 00 W to 45823 0 54 00 N, 127828 0 36 00 W, 2788 m depth, beam trawl; CAS-ICH 39821, male, 640 mm SL (light brown), off Oregon, 45821 0 30 00 N, 127833 0 0 00 W to 45821 0 42 00 N, 127838 0 30 00 W, 2800 m depth, beam trawl; CAS-ICH 40234, male, 446 mm SL (pale), off Oregon, Cascadia Abyssal Plain, 45827 0 48 00 N, 126817 0 24 00 W to 45827 0 0 00 N, 126821 0 0 00 W, 2606 m depth, beam trawl; CAS-ICH 40235, 307 mm SL (light brown), off Oregon, Cascadia Abyssal Plain, 45827 0 48 00 N, 126817 0 24 00 W to 45827 0 0 00 N, 126821 0 0 00 W, 2606 m depth, beam trawl; CAS-ICH 62566, 340 mm SL (light brown), off Oregon, Cascadia Abyssal Plain, 4485 0 18 00 N, 125823 0 35 00 W to 4487 0 6 00 N, 125821 0 48 00 W, 2940 m depth, beam trawl; LACM 45789 , 1205 mm SL (light brown), ca. 378N 1238W, ca. 3000 m depth .

Diagnosis.— Number of dorsal-fin rays 135–147, anal-fin rays 103–112, total vertebrae 78–83, pre-anal length 40–45% in SL, pelvic- to anal-fin origin 28–33% in SL, orbit length 8.0– 16 in % HL, otolith ostium width 24–30 in % sulcus length and 32–40 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, 5, and 7. Body moderately elongate, laterally compressed, tapering towards tail. Pectoral-fin depth 6.1–10 times in SL, tail length 1.67–1.81 times in SL, and preanal length 1.24–1.43 times in tail length. Head length 4.2–5.4 in SL and 1.75–2.38 in preanal length; head depth through eye 6.8–12 times in SL. Orbit circular, shorter than snout, 1.27–3.18 times in snout length, slightly larger in small specimens. Anterior gill arch with 8–9 long and 9–13 rudimentary rakers. Pseudobranchial filaments 0–3.

Origin of dorsal fin above vertebra 7–11, well in front of distal tip of pectoral fin. Pelvic fins with two rays each reaching about 1/3 from its base to anal-fin origin. Pectoral fins on lower half of body, rather short, 8.8–12 times in SL, and moderately wide at fin base in most specimens, the width 18–24 times in SL.

Otolith ( Fig. 3F–H ) oval in large-sized fish (length to height ratio 1.40–1.58) and more elongate in small-sized fish (length to height ratio 1.72–1.76), with slightly pointed posterior tip, anteriorly rather blunt. Sulcus long in large-sized specimens (61–74% of otolith length) and shorter in small-sized fish (51–57% of otolith length), with separate colliculi and located at the center of inner face. Ostium width 24–30% of sulcus length and 32–40% of ostium length in fish of 192 mm SL and larger; ostium width 44–49% of ostium length in two 188 and 190 mm SL juveniles.

Coloration.— Two freshly collected specimens from Japan, Northwest Pacific (ZMUC P2397444 and P2397445; 945–950 mm SL) with light brown body and head, unpaired fins slightly darker, especially posteriorly in tail region. A slightly larger fresh specimen (ZMUC P2397724) from same area (1020 mm SL) is entirely whitish. Long-term preserved specimens, including HT (larva), pale creamy or pale yellowish.

Distribution.— This species is distributed in the Pacific and Southeast Atlantic (ca. 1000 to 3360 m depth). There are no records from the Indian Ocean.

Remarks.— Among the studied specimens, the four females and eight males showed no sex-related differences in morphological or color characters. Head, orbit, and ostium length show negative allometry when the entire size range (i.e., small-sized juveniles to largest-sized adults) is considered ( Fig. 4 ). No such pattern was found for preanal and pelvic-fin length and ostium width. Two of the three smallest specimens (size range 188–190 mm SL) showed a relatively wide ostium compared to all other conspecifics (including the 192 mm SL specimen shown in Figs. 3F , 4 ), possibly indicating early life-history modification in otolith form. Like in Spectrunculus grandis , the largest specimen of S. radcliffei showed a clearly shorter pelvic fin ( Fig. 4 ).

SE Atlantic 47 15 23 24 32 S Indian Ocean n 48 19 30 30 40 Max NE Pacific Mean Min SW Pacific n 3 3 3 3 3 Max 54 19 28 27 38 NW Pacific Mean 51.0 18.5 27.0 26.8 36.3 Min 48 17 27 26 35 HT, NE Pacific (small) Ostium length Ostium width Ostium width in Otolith height Sulcus length Ostium length

Specimens from the South Atlantic show slightly shorter heads, narrower interorbitals, and deeper bodies than in the other areas of occurrence. However, data are insufficient for detailed quantitative population comparisons.

Distinction of each of the four species of Spectrunculus .—( Table 8) Spectrunculus stenostio differs from the other three species by the clearly narrower ostium and by the mostly higher number of total vertebrae; S. crassus differs from the other three species in the combination of low dorsal-fin, anal-fin, and vertebrae counts, mostly larger eyes and lower maximum size; S. radcliffei differs from the other three species in the combination of a mostly shorter preanal length, shorter pelvic- to anal-fin origin distance, and by higher anal-fin ray counts; S. grandis differs from the other three species in the combination of all nine characters.

Color patterns have no significance in species distinction except for fresh or recently collected specimens of the two North Atlantic species, with body and head color in S. crassus being mostly darker than in S. stenostio (see also Uiblein et al., 2008).

KEY TO THE SPECIES OF SPECTRUNCULUS

The key below is prepared to allow identification among the four species of Spectrunculus without necessary extraction of otoliths (see also Materials and Methods section). Consequently, distinction in otolith shape is indicated in parentheses.

1a.

1b.

: of %

2a.

2b. Dorsal-fin rays 135–148, anal-fin rays 101–112, total vertebrae 77–88, eye diameter in subadult or adult specimens 6.4–13 times in HL, maximum size

to 100 cm SL or larger, body and head color in freshly caught or recently fixed and/or preserved specimens pale gray or pale whitish, light brown or dark brown, all major oceans -------------------------------------------------------- 2 Dorsal-fin rays 121–139, anal-fin rays 91–102, total vertebrae 72–79, eye diameter in subadult or adult specimens 5.8–8.2 times in HL, maximum size 60 cm SL, body and head color in freshly caught or recently fixed and/or preserved specimens light brown in juveniles or subadults and dark gray or dark brown (rarely speckled) in larger specimens, Atlantic and E Pacific ------------ Spectrunculus crassus Pre-anal length 1.83–2.15 times in SL and 1.01– 1.15 in tail length (¼ subequal or only slightly shorter), distance between pelvic- and anal-fin origins 2.28–3.17 times in SL, total vertebrae 80–88,

all major oceans ---------------------------------------------------------------------------------- 3 Pre-anal length 2.22–2.48 times in SL and 1.24– 1.43 in tail length, distance between pelvic- and 3a.

3b.

anal-fin origins 3.02–3.58 times in SL, total vertebrae 78–83, Pacific and S Atlantic ---------------- S. radcliffei Dorsal-fin rays 135–137, anal-fin rays 101–105, total vertebrae 77–80, maximum size 130 cm SL (otolith ostium width 2.56–2.86 in its length and 4.2–4.4 times in sulcus length), Pacific -------- S. grandis Dorsal-fin rays 137–148, anal-fin rays 102–112 (106– 108 in the SW Pacific population [co-occurrence with S. grandis ]), total vertebrae 80–88, maximum size 110 cm SL (otolith ostium width 3.45–5.3 in its length and 4.8–6.7 times in sulcus length), N Atlantic, S Indian Ocean, and SW Pacific --------------------------------------------------------- S. stenostio

Figures

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.

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.