Stemonosudis elegans ( Ege, 1933 )

Stemonosudis elegans ( Ege, 1933) View in CoL

Fig. 1 View FIGURE 1 ; Table 1–2

Macroparalepis elegans Ege, 1933:232 View in CoL (type locality: eastern Australia off New South Wales, ca. 70 m; holotype: ZMUC P2318733). Ege, 1957: 23 (description).

Stemonosudis elegans ( Ege 1933) View in CoL : Post 1972:153 ( type catalog).

Material examined. ZHM 107186, formerly ISH 1559-1968 View Materials , 71.1 mm SL, off southern Brazil, southwestern Atlantic Ocean , 34°0'S, 47°34'W, 14 Feb.1968 GoogleMaps . ZMH 115498 View Materials , formerly ISH 33-1978 View Materials , 2 specimens, 96–124 mm SL, southwestern Atlantic Ocean , 38°02'S, 42°03'W, 25 May 1978 GoogleMaps . ZHM 115491, formerly ISH 13-1978, 136 mm SL, 34°56'S, 48°47'W, southwestern Atlantic Ocean , 30 May 1978 GoogleMaps .

Comparative material. ZMUC P2318733 View Materials , holotype, 53 mm SL, Dana station 3655, 33°39.5'S, 159°00'E, New South Wales, eastern Australia, ca GoogleMaps . 70 m [200 meters wire out]. AMS I.43095-029, 149 mm SL, Queensland, Australia. AMS I.47765-003, 146 mm SL , 35°04'S, 151°29'E, east of Jervis Bay , New South Wales, Australia, 13 Sep. 2017 GoogleMaps . AMS I.47876-007, 108 mm SL, 27°10'S, 155°35'E, East of Moreton Island , Queensland, Australia, 2 Sep. 2017 GoogleMaps .

Diagnosis. A species of Stemonosudis with the following combination of characters: body slender with 101–104 total vertebrae; 7 or 8 peritoneal sections; nostrils at about same vertical of posterior end of maxilla; anus at level of tip of pelvic fin or slightly behind; anus at about middle of V–D; anal-fin rays 34–37; lateral-line scales: prepelvic 39–41; predorsal 47–50; preanal 61–64; total 79–84. Body uniformly brown on dorsum, paler on ventrum; juveniles with pigment blotches on dorsum and ventral margin.

Description. Based on the Atlantic specimens. Morphometric and meristic data are provided in Tables 1 and 2.

Dorsal-fin rays 10; pectoral-fin rays 12–13; pelvic-fin rays 9; anal-fin rays 34–35; lateral-line scales: prepelvic 39–41; predorsal 47–50; preanal 61–63; total 79–81, including 75–78 large scales and 3–5 small ones on posterior portion. Vertebrae: prepelvic 39–40, prehaemal 42–43, predorsal 48–50, preanal 62–63, caudal 58–59, total 101. Gill rakers: 43–44 in total, 8 on upper limb (epibranchial) and 35–36 on lower limb, including 16–19 on ceratobranchial and 10–19 on hypobranchial; the 71.1 mm specimen has 1 + 14 + 2 = 17.

Body slender, but not extremely long, strongly laterally compressed, depth at pectoral fin 18.4–22.9 times in SL. Caudal peduncle moderately long, 1.8–2.3 times eye diameter. Ventral adipose fin developed along posterior half of abdominal ridge before pelvic-fin origin, well developed on margin between anus and anal-fin origin. Anus at about level of tip of appressed pelvic fin (slightly behind in 96.0 mm specimen), and about midpoint of V–D and well before midpoint of V–A.

Head long, its length 4.8–5.2 times in SL; snout slender, its length 8.9–9.0 in SL or 1.7–1.8 in HL. Mouth terminal, relatively large, with gape extending to about 1.5 eye diameter before eye; posterior portion of maxilla about 0.9 times eye diameter before eye; posterior portion of upper jaw with a skin fold end at about a vertical through anterior margin of eye; lower jaw slightly upturned at tip, with small distal tab of fleshy tissue. Eye small, its diameter 6.4–8.0 in HL. No light organs in front of eye or below eye. First suborbital bone slender, the fifth and sixth expanded posteriorly, and the seventh small. Interorbital space narrow, its width 9.9–11.3 in HL; some straight bony ridges present on top of head and snout. Two nostrils located very slightly before a vertical through posterior end of maxilla, about 1 eye diameter in front of eye. Sensory canals and pores on snout, cheek, operculum and jaws, but not especially numerous.

Dorsal fin well behind mid-length of fish and well behind pelvic fin, pre-dorsal length 1.6 times in SL. Pectoral fin long, 11.4–11.9 times in SL, with upper rays distinctly longer, about twice length of lower rays; its base behind posterior margin of gill cover, upper end of fin base at about same horizontal drawn through lower margin of eye; a small pocket present behind fin base. Pelvic-fin origin situated at about middle of the fish, pre-pelvic length 1.8–2.0 times in SL and V–D 37.5–42.3 % V–A. A slender axial scale present behind each pelvic-fin base. Anal fin originating on posterior fourth of body, pre-anal length 1.3 times in SL. V–A relatively long, 22.2–23.6 % of SL. Adipose fin above posterior portion of anal-fin base.

Two or 3 small fangs at tip of upper jaw, followed by single row of numerous (ca. 40) small, retrorse teeth, those on anterior portion of maxilla slightly larger, gradually becoming smaller posteriorly. Vomerine teeth absent. Two depressible fangs at front of each lower jaw, followed by a gap and then two rows of fangs arranged in 5 pairs; those of inner row long with knife-like tip and depressible; those in outer row much shorter, curved back and fixed, slightly covered by tissues. Two rows of fangs on anterior portion of palatine, anterior teeth forming 4–5 widely-spaced tooth pairs, those in outer row long and depressible, those in in outer row small and fixed; these fangs followed by single row of 5–6 small, widely-spaced fixed teeth on posterior portion. One row of 7–8 small, small teeth present on each side of tongue (basihyal).

Gill rakers present on all gill arches, small, shield-shaped and closely set to each other, each with 1 or 2 small teeth and narrow base. Teeth on pharyngeal arch relatively long, forming oval patch, with about 3 rows in middle. Single row of small teeth on each fifth ceratobranchial, both forming a V-shaped pattern. Gill filaments present on all four gill arches. Fourth arch mostly connected to gill chamber wall by membrane. Pseudobranchs present, within a deep pocket anteriorly.

Body scaleless except for a single row of lateral-line scales originating above pectoral girdle and running to about two-thirds the length of anal-fin base. Lateral-line scales slightly longer than wide, gradually becoming smaller and narrower posteriorly; 3 (some with 2) pores on margin of each scale, anterior pore largest, accompanied by an additional small pore on middle between two scales.

Luminescent duct absent.

Coloration. Fresh color unknown, but assumably similar to the preserved condition. Body light brown with somewhat regular rows of large melanophores on dorsum and dorsal surface of head, becoming uniformly brown behind dorsal fin; brown pigments on snout and jaw, below eye, and fins; pale elsewhere; mouth cavity, gill chamber, gill rakers and filaments all pale.

The 71.1 mm specimen has 5 blotches on dorsum, the first one well before dorsal fin, slightly behind midpoint between pectoral and dorsal fins, second on dorsal-fin base, third and fourth behind dorsal fin, and fifth at anterior base of adipose fin; another blotch present at origin of anal-fin base. This specimen has 7 broad peritoneal sections. In the 96 mm specimen the dorsum is more or less uniformly colored, only a blotch at anterior adipose fin base is present. The 114 mm specimen has the anterior peritoneal sections separated, with each section broad and large; the posterior sections are somewhat fused and estimated at 8 sections. The 136 mm specimen has all peritoneal sections completely fused.

Size. The largest specimen examined is 270 mm SL from Australia (Ho, pers. data).

Distribution. This species is widespread in the Indo-West Pacific Ocean ( Ege, 1957); newly recorded from the southwestern Atlantic Ocean. This species is now recognized as having a circumglobal distribution, although it is mostly found in the southern hemisphere.