Stemonosudis rothschildi Richards, 1967

Ho, Hsuan-Ching, Russell, Barry, Graham, Ken & Psomadakis, Peter N., 2019, Review of the Stemonosudis rothschildi species complex, with descriptions of two new species from the Indo-west Pacific Ocean (Aulopiformes: Paralepididae), Zootaxa 4702 (1), pp. 216-229 : 218-222

Stemonosudis rothschildi Richards, 1967

Rothschild’s barracudina

Figs. 1 , 2A ; Tables 1–2

Stemonosudis rothschildi Richards, 1967:35 (type locality: off Hawaii Islands). Masuda et al., 1984: 77, pl. 68 (description; Japan); Paxton et al., 1989:248 (list; Australia); Fukui & Ozawa, 2004:293; Mundy, 2005:207 (list: Hawaii); Paxton et al., 2006:494 (list; Australia); Larson et al., 2013:48 (list; Australia).

Maculisudis longipinnis Kotthaus, 1967:82 , figs. 87–90 (type locality: East of Mombasa, Kenya, 450 meters). Post, 1971:738 (synomyzation).

Specimens examined. Forty-six specimens, 105–212 mm SL. Western Australia: AMS I.22826-001 (4, 193–212), FRV Soela, sta. So 2/82/43,45, 18°44’S, 117°02’E, 210 km north west of Port Hedland, 396–406 m, Engel trawl, 13 Apr. 1982, coll. J. Paxton & M. McGrouther. AMS I.22822-020 (2, 187–193), FRV Soela, sta. So 2/82/39, 18°23’ S, 117°41’E, 200 km northwest of Port Hedland, 396–418 m, Engel trawl, 11 Apr. 1982, coll. J. Paxton & M. Mc- Grouther. CSIRO CA 3754 (1, 192), CA 3755 (1, 176) and CA 3756 (1, 180), FRV Soela, sta. So 1/83/69, 18°3.5’S, 118°13’E– 17°56.7’S, 118°21.2’E, SW of Imperieuse Reef, 418–420 m, prawn trawl, 5 Feb. 1983. CSIRO H 2074- 03 (1, 191) and H 2074-04 (2, 170–177), 17°50’S, 118°33’E, SW of Rowley Shoals, 420 m, Courageous trawl, 12 Feb. 1989, coll. A. Williams. CSIRO H 7136-21 (1, 192), 14°20’S, 122°10’E– 14°16’S, 122°16’E, S of Scott Reefs, 358–360 m, demersal trawl, 14 Dec. 2010. CSIRO H 7137-04 (1, ca. 140), 16°00’S, 120°33’E– 16°13’S, 120°27’E, W of Cape Leveque, 420 m, demersal trawl, 14 Dec. 2010. NMV A 29699 -009 (2), 14°50’49”S, 121°26’26”E, NW of Cape Leveque (Leveque L27 transect), 382–401 m, 26 Jun. 2007. NMV A 29700 -015 (1), 14°36’31”S, 121°19’46”E (Leveque L27 transect), 709–712 m, 26 Jun. 2007. NMV A 29702 -011 (1), 14°49’02”S, 121°27’33”E (Leveque L27 transect), 392–407 m, 27 Jun. 2007. Taiwan: NMMB-P24631 (1, 125), Dong-gang, Pingtung, southwestern Taiwan, 27 Jul. 2016. NMMB-P31496 (5, 105–140), NMMB-P30961 (11, 174–185), NMMB-P30962 (13, 175–187), Dongsha Islands, South China Sea, 13 Feb. 2019. Japan: NSMT-P92268 (1, 160), off Pacific coast of Tohoku, Honshu, western Japan, 1 Nov. 2008, coll. T.P. Satoh. Western Atlantic Ocean: NSMT-P31655 (1, 127), R/V Nisshin-maru, 7°44’N, 54°11’W, Suriname, trawl, 480 m, 29 Sep. 1979. NSMT-P40155 (1, 120), Suriname, no other data.

Diagnosis. A species of the S. rothschildi species complex with relatively moderately slender body, both depth 15.9–18.8 in SL; 5 saddles on dorsum before DFO and 3 on abdominal margin before VFO; 39–41 prepelvic and 50–52 predorsal vertebrae; 9–13 vertebrae in V–D; and PVLL 39–41 and PDLL 50–52.

Description. Dorsal-fin rays 9 (rarely 10); pectoral-fin rays 12–13 (mainly 12); pelvic-fin rays 9; anal-fin rays 32–35. Lateral-line scales: 39–41 PVLL, 50–52 PDLL, 56–60 PALL, 75–84 in total, includes 3–5 small ones on rear portion. Vertebral counts: 42–44 prehaemal, 46–48 caudal, 39–41 prepelvic; 50–52 predorsal; 56–60 preanal and 89–92 in total.

Body moderately slender, strongly compressed, body depth 15.9–18.8 times in SL; ventral profile of belly near- ly straight; greatest depth at about anterior 1/3 of the body. Caudal peduncle short, slightly longer than eye diameter. Well-developed, moderately narrow ridge between pectoral and pelvic fins. Ventral adipose fins weakly developed between pectoral and pelvic fins, well-developed between anus and anal fin. Anus at tip of appressed pelvic fin, well in front of DFO.

Head moderately slender, slightly wider at opercle than body, its length 4.5–5.1 in SL. Snout moderately long and pointed distally, its length 1.7–1.9 in HL. Mouth terminal, moderately large, its gape extending to or slightly be- yond anterior margin of eye; tip of lower jaw slightly upturned, with small blunt fleshy tip. Eye small and rounded, its diameter 6.4–7.9 in HL. No light organ in front of or on lower margin of eye.

Two nostrils close together, slightly, but clearly before posterior end of maxilla, about 2/3 eye diameter in front of eye. Interorbital flattened, its width 8.8–11.4 in HL, with two lateral, compressed, longitudinal ridges on each side. Upper jaw length 1.9–2.1 in HL, maxilla terminating about 1/3–1/2 eye diameter before vertical through ante- rior margin of eye. Opercle thin, posterior margin bluntly pointed, its lower margin notched around base of pectoral fin. Gill membranes joined far forward, before vertical through anterior margin of eye, free from isthmus. Numerous sensory canals on snout, cheek, operculum, and jaws; numerous sensory pores on dorsal surface of snout and lower surface of lower jaw.

Pectoral fin slender, originating above level of lower margin of eye, slightly behind vertical through posterior margin of gill cover. Small pocket behind pectoral-fin base. DFO about 1/4 SL before caudal fin, well behind VFO and midpoint of V–A. VFO well behind middle of body. Very small axial scale, mostly embedded, behind pelvic-fin base. Anal fin originating at about 1/5 SL before caudal fin.

Premaxilla with 2 or 3 small canines, followed by row of many small, closely-spaced, fixed, retrose teeth along upper jaw, gradually smaller posteriorly. Vomerine teeth absent. Mandible with 3 depressible fangs at front, followed by two rows of large broadly-spaced teeth, forming 5–8 tooth pairs, those in inner row long, with knife-like tip, and depressible; those in outer row much shorter, recurved and fixed. Two rows of teeth on each palatine, anterior 5–7 forming widely-spaced tooth pairs, those in inner two depressible and long, those in outer row short and fixed, followed by single row of short and fixed teeth. Tongue fleshy, spatulate anteriorly, with two parallel longitudinal rows of teeth extending length of glossohyal, each row with several small teeth. Basihyal without teeth.

Gill rakers ( Fig. 2A ) present but not easy to observe without staining; better developed than in two other congeners (see below); better developed on the outer two arches than other two. Each raker with 1–3 small teeth and narrow base. Total rakers 29–35, 3–5 rakers on epibranchial, 14–16 relatively large rakers on ceratobranchial, and 11–14 small rakers on hypobranchial. Teeth on pharyngeal arch slender, in oval patch, about 5 rows at middle. Single row of small teeth on fifth ceratobranchial. Pseudobranchs present, inside deep pocket above first gill arch.

Body devoid of scales, except for single row of lateral-line scales originating above pectoral girdle and running to above about posterior third to fourth of anal-fin base. Lateral-line scales as high as wide, becoming gradually smaller and narrower posteriorly; a cluster of 3–5 pores on each side of scale, outermost pore largest.

No luminescent duct in abdominal cavity. Peritoneal sections well-developed and separated in adults.

Coloration. Body translucent to light dusty when fresh, yellowish to grayish brown in preservation. Upper fourth of body covered with small chromatophores; lateral line densely covered with chromatophores, gradually becoming scattered on ventral half of body. Dense chromatophores on snout, both lips and abdominal ridge; scattered chromatophores on top of head, nape, and around eye. Very fine chromatophores forming large saddles on dorsum and ventral margin; 9 or 10 on dorsum, 5 before DFO, 1 at dorsal-fin base, 2 between dorsal and adipose fins, 1 or 2 on caudal peduncle; 8 saddles on ventral margin, 3 in front of VFO, 1 at pelvic-fin base, 1 near AFO, 1 on middle of anal-fin base and 1 or 2 on caudal peduncle; the last 2 or 3 pairs of dorsal and ventral saddles usually fused to each other at mid-flank. Peritoneal membranes divided into 9 to 11 (mostly 10) sections, visible through belly. Pectoral and pelvic fin transparent to slightly hyaline; upper half of dorsal fin black; posterior portion of anal-fin blackish; caudal fin black.

Size. The largest specimen examined in this study is 212 mm SL.

Distribution. Known from circumglobal in tropical seas, including the Hawaiian Islands, but not found in the eastern Pacific Ocean; collected from continental slope (358–712 m).

Remarks. Richards (1967) described Stemonosudis rothschildi based on a single specimen collected from the stomach of a lancetfish ( Alepisaurus richardsoni [= A. ferox ]) taken from the central North Pacific Ocean. Post (1971) documented five young adolescents from the Caribbean Sea and suggested it had a worldwide distribution.

Although this species were documented from Japan ( Masuda et al., 1984) Australian waters ( Paxton et al., 1989, 2006), no detailed morphological data were provided. We examined a number of specimens collected off Western Australia, Taiwan and Japan, and two specimens from the Caribbean Sea. Their meristic values agree with the original descriptions and additional information provided by Post (1971). Post (1971) also provided the evidence for synonymizing Maculisudis longipinnis Kotthaus, 1967 with Stemonosudis rothschildi .

Post (1982) reported one specimen collected from Java (146.4 mm SL) with several distinct characters; together with additional specimens, it is described as a new species below.

Figures

FIGURE 1. Stemonosudis rothschildi Richards, 1967, NMMB-P39061, 1 of 11, 176 mm SL. A. Lateral view. B. Lateral view of head. C. Lateral view of trunk region showing the fins position. Arrows indicatethe DFO (above), VFO (lower left) and AFO (lower right). Anterior to left.

FIGURE 2. First gill arch and its rakers of three Stemonosudis species. A. S. rothschildi, NMMB-P39061, 176 mm SL. B. S. multifasciata sp. nov., NMMB-P30956, paratype, 247 mm SL, arrow indicates the rudimentary rakers. C. S. retrodorsalis sp. nov., from the holotype, arrow indicates the fused rakers. Anterior to right; not to scale.