Opistognathus stigmosus, Smith-Vaniz, 2004

Smith-Vaniz, William F., 2004, Descriptions of Six New Species of Jawfishes (Opistognathidae: Opistognathus) from Australia, Records of the Australian Museum 56 (2), pp. 209-224 : 215-216

Opistognathus stigmosus n.sp.

Figs. 3C, 7; Tables 1–4

Opistognathus sp. — Randall et al., 1990: 356, unnumbered colour fig. (brief diagnosis; common name “coral sea jawfish”).

Type material. HOLOTYPE: AMS I.22583-004, male (70.5), Australia, Queensland, Escape Reef , 15°49'S 145°50'E, outer reef, 29 m, G. R. Allen, T. Ayling and W. Starck, 29 Oct. 1981, sta. ER 81–11. P ARATYPES: 3 specimens, 42.9–62.5 mm, all from the Great Barrier Reef. AMS I.22583-037, sex undetermined (42.9), same data as holotype; WAM P.27467- 004, gravid female (58.5), Escape Reef, G. R. Allen et al., 30 Oct 1981; WAM P.29641-001, male (62.5), Lihou Reef, Juliette Cay, 17°21'S 151°33'E, 20–23 m, G. R. Allen, 14 Nov. 1987.

Diagnosis. A species of Opistognathus with dorsal fin X, 19; body with about 38–45 oblique scale rows in longitudinal series, and with scales absent anterolaterally forward of verticals from 5th to 7th dorsal-fin spines; lower half of sides with longitudinal row of 7 or 8 large white spots, the largest with a dark brown border and covered by appressed pectoral fin; vomerine teeth absent.

Description. Dorsal-fin rays X, 19. Anal-fin rays II, 18. Pectoral-fin rays 19–21. Caudal fin: procurrent rays 5+4– 5, segmented rays 8+8, middle 14 branched, total elements 25–26; hypural 5 absent. Vertebrae: 10+23; last pleural rib on vertebra 10; epineural ribs 13–14.

Supraneurals absent, insertion pattern 0/0/1/1+1/1/. Gill rakers 7–9+15–18 = 22–27.

Scales absent on body anterolaterally forward of verticals from 5th to 7th dorsal-fin spines, and from head, nape, above lateral line, pectoral-fin base, breast and anterior 1 3 of belly. Body with about 38–45 oblique scale rows in longitudinal series. Lateral-line terminus below verticals from 7th or 8th segmented dorsal-fin rays (total element position 17 or 18). Lateral line pores numerous, arranged in multiple series above and below embedded lateral-line tubes. Cephalic sensory pores very numerous, in adults completely covering most of head, including all of predorsal area except a small area immediately adjacent to dorsal-fin origin; mandibular pore positions 1–3 occupied by relatively large, single pores, 4th position with 2– 5 pores, 5th position with 6–12.

Anterior nostril distinctly closer to posterior nostril than to dorsal margin of upper lip, and with a simple, relatively long tentacle on posterior rim that when depressed usually barely reaches to or almost to margin of orbit; height of tentacle about 1.5 times maximum diameter of posterior nostril. Dorsal fin low anteriorly gradually increasing in height posteriorly; profile relatively uniform with only a slight change in fin height at junction of spinous and segmented rays. Dorsal-fin spines relatively short and straight, at most only slightly curved distally and without flexible tips; skin covering tips of spines with slightly swollen fleshy tabs; all segmented dorsal- and anal-fin rays branched distally. Outermost segmented pelvic-fin ray not tightly bound to adjacent ray, interradial membrane incised distally. Upper margin of opercle straight and slightly rounded posterodorsally; posterior margin of preopercle indistinct without a free margin. No papillae on inner surface of lips. Fifth cranial nerve passes under A1 branch of adductor mandibulae.

Upper jaw not sexually dimorphic, extending 0.4 to 0.5 eye diameters behind posterior margin of orbit; maxilla widest at end and truncate, without flexible lamina posteriorly; supramaxilla present, small and terminally positioned. Jaws subequal. Premaxilla with moderate conical teeth in outer row that become progressively smaller and more closely spaced posteriorly; 1–3 irregular rows of smaller, sharply pointed, inner teeth anteriorly, those in innermost row slightly larger and canted backwards. Dentary with outer row of conical teeth, all about the same size and about ½ size of largest premaxillary teeth; 1–4 irregular, inner rows of slightly smaller conical teeth anteriorly, those in innermost row slightly canted backwards. Vomerine teeth absent. Infraorbital bones tubular, with wide openings for sensory canals ( Fig. 3C), third infraorbital relatively robust with a slight suborbital shelf.

Measurements of the 70.5 mm holotype (in parentheses) and 3 paratypes, 42.9–62.5 mm, as percentage of SL: predorsal length (35.2) 32.8–35.0; preanal length (54.9) 55.6–58.6; dorsal-fin base (69.1) 67.4–71.8; anal-fin base (34.5) 36.3–36.7; pelvic-fin length (23.0) 23.0–23.6; caudalfin length (19.4) 19.4–22.3; depth at anal-fin origin (15.6) 13.9–16.3; head l ength (34.5) 33.5–35.0; orbit diameter (11.5) 11.5–12.1; upper jaw length (19.3) 17.3–19.0. As percentage of head length: postorbital head length (61.2) 59.3–61.7; upper jaw length (55.9) 51.5–54.3; postorbital jaw length (15.2) 12.8– 14.0; orbit diameter (33.3) 34.2–34.7.

Preserved coloration. Head and body overall tan, longitudinal row of 7 or 8 large white spots on lower half of sides; the largest with a dark brown border, widest ventrally, and covered by appressed pectoral fin; a second row of smaller indistinct pale spots above primary row; laterally a small dark spot present opposite dorsal 1 3 of otherwise pale pectoral-fin base; this spot on mesial side of pectoral-fin base where it may continue downward as a diagonal mark; small dark blotch also present on body immediately above pectoral-fin base; head and sides punctuated with widely scattered small dark brown spots, including one just behind posterodorsal margin of upper jaw; other dark spots ring orbital rim, those in interorbital region always very dark and symmetrically arranged in bilateral pairs; conspicuous dark spots or bands on upper and lower lips, two largest specimens each with 6 bands on lower lip; inner lining of maxilla and mouth immaculate; spinous dorsal fin with submarginal narrow dark stripe; tips of dorsal-fin spines with noticeably pale fleshy tabs; soft dorsal and anal fins with narrow dark suprabasal stripe bordered above by diffuse submarginal brown stripe, and dark bands or spots; caudal fin with pair of pale basicaudal spots (separated by a narrow inverted wedge-shaped blotch with a pale centre) followed by 1 or 2 dusky bands separated by pale interspaces; pelvic and pectoral fins immaculate.

Live coloration (based on Randall et al., 1990): body and head various shades of brown, pale spots and markings white; iris yellow with a few narrow dark bands radiating from pupil.

Etymology. The specific epithet, from the Latin stigmosus (full of marks), refers to the conspicuous, small dark spots on the head of this species.

Distribution. Known only from the Great Barrier Reef (Escape Reef) and the Coral Sea Plateau (Lihou Reef) in 20– 29 m.