Opistognathus verecundus, Smith-Vaniz, 2004
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Opistognathus verecundus n.sp.
Figs. 2C, 3E, 9, 10; Tables 1–4
Opistognathus sp. —Larson & Williams, 1997: 366 (listed; Darwin Harbour).
Type material. HOLOTYPE: NTM S.10016-003, male (52.6), Australia, Northern Territory, Cobourg Peninsula, E. side Coral Bay , 11°11'S 132°04'E, 5–6 m, Helen K. Larson and P. Homes, 18 Oct. 1981 GoogleMaps . PARATYPES: 28 specimens, 14.2–48.1 mm, all taken with the holotype. AMS I.33644-001 (4, 35.2–39.4), ANSP 167416 View Materials (4, 29.5–48.1,
1 C&S), NTM S.10016-046 (12, 14.2–47.2), USNM 320261 (4, 25.1–44.8), WAM P.30593-001 (4, 33.5–37.3).
Diagnosis. A species of Opistognathus with dorsal fin X– XI, 14 or 15 (typically XI, 14); upper jaw sexually dimorphic with flexible lamina posteriorly, end of maxilla slightly rounded (females) becoming increasingly elongate and scimitar-shaped (adult males); oblique scale rows 39–54 in longitudinal series; total gill-rakers on first arch 23–26; spinous dorsal fin with a single brownish spot, if present, between spines 2–4.
Description. Dorsal-fin rays X–XI, 14 or 15 (typically XI, 14). Anal-fin rays III, 14 (rarely 13 or 15). Pectoral-fin rays 18 or 19. Caudal fin: procurrent rays 4–5+3–5, segmented rays 8+8, middle 12–14 branched, total elements 23–26; hypural 5 absent. Vertebrae: 10+18 (19 in one of 29 specimens); last pleural rib on vertebra 10; epineural ribs 11–12. Supraneurals 1 (based on radiographs but in the only C&S specimen a tiny cartilaginous ball is present in the first interneural space), insertion pattern 0/S/1/1+1/1/. Gill rakers 8–9+15–17 = 23–26.
Scales absent on head, nape, above lateral line, pectoralfin base, breast and anterior ¼ to ½ of belly. Body with about 44–54 oblique scale rows in longitudinal series.
Lateral-line terminus below verticals from 2nd to 4th segmented dorsal-fin rays (total element position 13–15).
Lateral line pores numerous, arranged in multiple series above and below embedded lateral-line tubes. Cephalic sensory pores numerous, 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 1–3 (usually 2) pores, 5th with 3–7 pores.
Anterior nostril about mid-way between posterior nostril and dorsal margin of upper lip, consisting of a short tube with posterior rim longer, that when depressed does not reach or just reaches margin of posterior nostril; height of tube shorter than to about equal maximum diameter of posterior nostril. Dorsal fin moderately low anteriorly, with profile relatively uniform without change in fin height at junction of last spine and anterior segmented rays. Dorsalfin spines relatively slender and slightly curved distally, with flexible tips; all segmented dorsal- and anal-fin rays branched distally or 1st anal ray unbranched. 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 section of adductor mandibulae.
Upper jaw sexually dimorphic (longest in adult males) and extending 1.1 to 2.1 eye diameters behind posterior margin of orbit; maxilla widest before end, with flexible lamina posteriorly ( Fig. 2C), scimitar-shaped in adult males; supramaxilla moderately large and subterminally positioned. Jaws subequal, lower slightly included. Premaxilla with an outer row of moderately large, sharply pointed, conical teeth, those near posterior end of jaw noticeably smaller and more closely spaced; 2 or 3 irregular inner rows of much smaller conical teeth present anteriorly, with those adjacent to premaxillary symphysis slightly enlarged. Dentary with an outer row of conical teeth that are blunter anteriorly, those on posterior half of dentary largest and slightly hooked inward; 2 or 3 inner rows of slightly smaller, conical teeth anteriorly, those in innermost row canted backwards. Vomerine teeth absent. Infraorbital bones tubular, with wide openings for sensory canals ( Fig. 3E); 3rd infraorbital relatively robust but without a suborbital shelf. Second pharyngobranchial rod-shaped with distal end slightly expanded.
Measurements of the 52.6 mm male holotype (in parentheses) and 15 paratypes, 9 ƋƋ 35.9–48.1 mm and 6 ♀♀ 35.2–47.2 mm, as percentage of SL: predorsal length (31.6) 28.9–32.0; preanal length (55.1) 52.4–56.6; dorsalfin base (74.3) 65.0–76.1; anal-fin base (38.8) 36.3–40.8; pelvic-fin length (20.0) 20.4–22.8; caudal-fin length (21.5) 19.8–22.8; depth at anal-fin origin (15.0) 12.5–16.2; head length (32.7) 29.8–32.6; orbit diameter (8.3) 8.1–9.3; upper jaw length (25.9) 20.4–24.5 ƋƋ, 19.0–21.1 ♀♀. As percentage of head length: postorbital head length (68.9) 65.2–68.4; upper jaw length (79.1) 65.2–78.9 ƋƋ, 61.6– 66.5 ♀♀; postorbital jaw length (52.3) 33.9–45.3 ƋƋ, 29.9–35.6 ♀♀; orbit diameter (25.3) 25.7–29.9.
Preserved coloration. Head and body ground colour light tan, with darker freckling; in larger specimens branchiostegal membranes and pectoral-fin base finely peppered with melanophores; inner lining of maxilla and adjacent membranes with 2 brownish stripes (best developed in adult males) that when mouth is closed are partially visible as lateral streaks on expanded part of the upper jaw; buccal pigmentation ( Fig. 10) consisting of diffuse dusky area on floor of mouth in front of esophageal opening and a pair of slightly separated dark blotches on roof of mouth behind upper pharyngeal toothplates; in some specimens, a series of small dark blotches present on sides and about 8 equally spaced blotches on dorsum along dorsal-fin base; in a few specimens first 2 blotches relatively dark and extending onto dorsal fin; dorsal and anal fins dusky with blotches and pale spots that that tend to form rows; in some specimens a pair of pale basicaudal spots evident and caudal fin with several indistinct narrow dusky bands; pelvic and pectoral fins immaculate.
Etymology. The specific epithet is from the Latin verecundus (bashful or shy), in allusion to the burrowdwelling habit.
Distribution. Known only from the type locality off Cobourg Peninsula, northern Australia, where collected in 5– 6 m.
Remarks. This species is apparently most closely related to the allopatric O. solorensis Bleeker 1853 , known from Indonesia, Philippines and Taiwan. Both have essentially identical upper jaw structures, dentition, fin ray and vertebral counts and buccal pigmentation. Opistognathus verecundus differs from O. solorensis in having fewer gill-rakers, with 15–17 (versus 18–20) on the lower limb and a total of 23–
26 (vs. 27–33), only 44–54 oblique scale rows in longitudinal series (vs. typically 58–69), and only brown spots or markings anteriorly on the spinous dorsal fin, (vs. one or two black spots in this position).
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