Stemonosudis multifasciatus, Ho & Russell & Graham & Psomadakis, 2019

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 : 222-224

publication ID	https://doi.org/ 10.11646/zootaxa.4702.1.19
publication LSID	lsid:zoobank.org:pub:F9EE15A8-61EB-45F6-A5A5-7660A67B91B5
persistent identifier	https://treatment.plazi.org/id/326C87FD-FFB1-FFD1-FF3A-FBC962B7E528
treatment provided by	Plazi
scientific name	Stemonosudis multifasciatus
status	sp. nov.

Treatment

Stemonosudis multifasciatus sp. nov.

Multi-blotch barracudina

Figs. 2B View FIGURE 2 , 3 View FIGURE 3 A–D; Tables 1–2 View TABLE 1 View TABLE 2

Holotype. NMMB-P30955 (280), sta. 139, 11°01’49.8”N, 96°53’31.8”E, off Myanmar, Andaman Sea , Eastern Indian Ocean, 329.5–332 m, 24 Sep. 2018. GoogleMaps

Paratypes. Six specimens, 248–283 mm SL: NMMB-P30956–7 (2, 248–249), sta. 114, 12°43’16.8”N, 96°45’21.6”E, off Myanmar, Andaman Sea, Eastern Indian Ocean , 308–310 m, 20 Sep. 2018 GoogleMaps . NTM S.12288-039 (1, 280), N.T. Fisheries, ca. 9 o 46’S, 130 o 14’E, east of Evans Shoal, Northern Territory, Arafura Sea , 270–300 m, 5 Sep. 1987 GoogleMaps . NTM S.12455-002 (1, 254), FV Napier Pearl, ca. 9 o 46’S, 130 o 00’E, north of Bathurst Island, Northern Territory, Arafura Sea , 275 m, 7 Jul. 1988 GoogleMaps . SAIAB 14159 View Materials (1, 283), Stn 558, 6°29’N, 97°54.4’E, off Sumatra, Anda- man Sea, eastern Indian Ocean , trawl, 330 m, 18 Jul. 1980, coll. coll. P. Heemstra. GoogleMaps SAIAB 65701 View Materials (1, 267), 6°345’N, 98°00’E, Molluca Straits, Indonesia, Andaman Sea, eastern Indian Ocean , bottom Trawl , 320 m, 31 Jul. 1980, coll. P. Heemstra.

Diagnosis. A species of the S. rothschildi species complex with 16 saddles on dorsum, 10 before DFO; 49–51 caudal and 93–95 total vertebrae; vertebrae between VFO and DFO 8–11; DFO relatively forward in position, pre- dorsal length 71.8–73.6% SL, V–D 52.3–63.0% V–A; upper jaw 41.8–43.8% HL, lower jaw 55.8–62.5%.

Description. Holotype first, paratypes in brackets after. Dorsal-fin rays 9 (8–9); pectoral-fin rays 13 (12–13); pelvic-fin rays 9; anal-fin rays 34 (32–35). Lateral-line scales: 40/41 (40–41) PVLL; 51/52 (50–52) PDLL; 59/60 (59–60) PALL; 78/79 (75–79) in total, including 4 or 5 (3–5) smaller scales at rear. Vertebral counts: 44 (44–45) prehaemal; 49 (49–51) caudal; 42 prepelvic; 50 (50–53) predorsal; 58 (58–61) preanal; 93 (93–95) in total.

Body moderately elongate, relatively deep and strongly compressed, ventral profile of belly nearly straight or slightly convex; greatest depth of body right at anterior third of body. Well-developed, moderately narrow ridge between head and pelvic fins. Ventral adipose fins weakly developed between pectoral and pelvic fins, well-developed between anus and anal fin.

Head slender and pointed, length 5.3 (4.8–5.7) in SL. Snout moderately long, its length 2.0 (1.8–2.0) in HL. Two nostrils close together, at about same vertical through posterior end of maxilla or slightly forward, about 0.8 eye diameter before eye. Eye round, diameter 7.0 (7.0–7.6) in HL. Postorbital length less than half of HL. Interorbital flattened, width 10.8 (10.2–10.8) in HL, with two lateral, compressed, longitudinal ridges on each side of interorbital space.

Mouth terminal, moderately large, its gape extending slightly beyond anterior margin of eye; tip of lower jaw slightly upturned, with small blunt fleshy tip. Upper jaw length 2.4 (2.3–2.3) in HL, maxilla terminating about 0.8 eye diameter before vertical from anterior margin of eye. Opercle thin, with posterior margin bluntly pointed, its lower margin slightly notched around base of pectoral fin. Numerous sensory canals on snout, cheek, operculum, and jaws; numerous sensory pores on dorsal surface of snout and lower surface of lower jaw. Gill membranes joined at throat region, before a vertical through anterior margin of eye, and free from isthmus posteriorly.

Pectoral fin slender, originating level of lower margin of eye; fin rays long, about equal to snout length, fin length 9.2 (9.2–10.9) in SL. Dorsal-fin at about 1/4 SL before caudal fin, well behind VFO and middle of V–A. Pelvic fin originating well before vertical through DFO. Very small axial scale, mostly embedded behind pelvic-fin base. Anus slightly behind tip of the appressed pelvic fin (under tip of pelvic fin in some paratypes). Anal fin originating at about 1/5 SL before caudal fin.

Premaxilla with 3 small depressible canines followed by series of many closely-spaced, fixed, retrorse teeth. Mandible with single short fixed tooth on crown each side of symphysis behind which is a larger and depressible canine, then 3 smaller canines anteriorly; followed by 5 or 6 large broadly-spaced depressible canines, each accompanied anteriorly by short fixed tooth. Vomer without teeth. Palatine with 5 enlarged widely-spaced depressible teeth, each of second and third teeth accompanied by moderately large fixed tooth, followed by single row of short, fixed retrorse teeth. Tongue fleshy, spatulate anteriorly, with 2 parallel longitudinal rows of teeth extending length of glossohyal, each row with 7–9 small teeth. Basihyal without teeth.

Gill rakers small, present on the epibranchial and ceratobranchial on the outer 2 arches only, absent or only few rudimental teeth on all hypobranchials and the inner 2 arches. Each raker with 1–3 short teeth. Total 24–30 rakers; 5–7 rakers on eipbranchial, 15–20 small ones on ceratobranchial, and 0–3 rudimental ones on hypobranchial ( Fig. 2B View FIGURE 2 ). Row of small teeth on fifth cerotobranchial; teeth on pharyngeal arch small, in oval patch. Pseudobranches well-developed, inside deep pocket above first gill arch.

Body devoid of scales, except for single row of lateral-line scales originating from above pectoral girdle and running to above about posterior third of anal-fin base. Anterior lateral-line scales slightly wider than high, gradually becoming smaller and becoming narrower posteriorly; those in anterior half of lateral line shield-shaped, with concave on upper and lower margins; each scale with 3 pores above and below posterior half; scales in the posterior portion usually with 1 pore.

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

Coloration. Fresh color unknown. Color when preserved, body blackish, densely covered with fine chromatophores; 16 saddles, consisting of very fine chromatophores, on the dorsum, those in odd numbers larger; 10 before dorsal fin; 1 at dorsal-fin base; 3 between dorsal-fin and adipose fin; 1 at adipose fin and 1 at caudal fin base, latter 2 crossing caudal peduncle. Three indistinct ventral saddles before pelvic fin, 1 at pelvic-fin base, 1 at anterior portion of anal-fin base, 1 below adipose fin and 1 at caudal-fin base, the lateral 2 connecting to the last 2 saddles on dorsum, and forming bands.

Pectoral fin blackish with white base; pelvic fin with black base and white margin; dorsal fin with scattered chromatophores; adipose fin blackish; caudal fin with dense chromatophores on upper lobe and scattered ones on lower lobe, base and middle rays whitish. Dense chromatophores on anterior portions of jaws, dorsal surface of head, and branchiostegal membranes; gill chamber pale. Ventral ridge on abdomen with scattered chromatophores and ventral adipose fin densely pigmented.

Size. The largest specimen examined is 283 mm SL.

Etymology. The specific name is derived from the diagnostic character of many saddles on dorsal and ventral margins of body.

Distribution. Know from the type series collected from Arafura Sea and Andaman Sea at continental slope (270–332 m).

Remarks. Stemonosudis multifasciata is most similar to S. rothschildi in having relatively few anal-fin rays (32–35, vs. 35 or more in other Stemonosudis , except for one species which has 30) and more blotches on dorsum anterior to DFO (5 or more, vs. 0–3). It differs from S. rothschildi mainly in having 10 blotches on dorsum before DFO (vs. 5 in S. rothschildi ), 93–95 total vertebrae (vs. 89–92). The two species also differ in: head depth 3.9–4.6% SL (vs. 4.6–5.3% SL); predorsal length 71.8–73.6% SL (vs. 73.3–75.3% SL); D–A 6.8–8.7% SL (vs. 4.4–6.5% SL), dorsal-fin base 2.0–2.4% SL (vs. 2.8–3.1% SL); snout length 9.3–10.8% SL (vs. 10.7–11.6% SL); upper-jaw length 7.5–9.2% SL (vs. 9.6–10.8% SL); lower-jaw length 10.4–12.0% SL (vs. 12.8–13.5% SL); V–D 52.3–63.0% V–A (vs. 64.7–75.7% V–A) (see Table 1 View TABLE 1 ). However, as only a few specimens of S. multifasciata were available, these ranges may increase and overlap, when more material is caught.

The gill rakers in S. multifasciatus are relatively weakly-developed ( Fig. 2B View FIGURE 2 ) compared to the two other species in the complex ( Figs. 2A & 2C View FIGURE 2 ). Ho & Duhamel (2019) documented that the adults of some members in the subfamily Paralepidinae had reduced jaw teeth and gill rakers. However, no member of Lestidiinae has been observed with reduction of teeth or gill rakers. Because all our specimens are relativly large (248–280 mm SL), and no small specimens were available, the condition of the gill rakers in juveniles awaits further investagation.