Squatina legnota, Last, Peter R. & White, William T., 2008

Last, Peter R. & White, William T., 2008, Three new angel sharks (Chondrichthyes: Squatinidae) from the Indo-Australian region, Zootaxa 1734, pp. 1-26 : 12-16

publication ID	https://doi.org/ 10.5281/zenodo.181433
DOI	https://doi.org/10.5281/zenodo.5689527
persistent identifier	https://treatment.plazi.org/id/03F887AA-9C1C-FFD7-FF3E-FB44595BF9FC
treatment provided by	Plazi
scientific name	Squatina legnota
status	sp. nov.

Treatment

Squatina legnota View in CoL new species

Indonesian Angel Shark

Figs 4 View FIGURE 4 , 5 View FIGURE 5 , 8 View FIGURE 8 b, Table 3 View TABLE 3 .

Squatina sp. 1: White et al., 2006, Economically Important Sharks & Rays of Indonesia, pp 76, 77, fig.

Holotype. MZB 15500, female 471 mm TL, Cilacap fish landing site, Central Java, Indonesia, 07°44' S, 109°00' E, 2004.

Paratype. CSIRO H 6565–01, adult male 1252 mm TL, Tanjung Luar fish landing site, Lombok, Indonesia, 08°45' S, 116°35' E, 9 Sep. 2004.

Other material. Adult male 1341 mm TL, not retained, collected at same locality as paratype, 10 Mar. 2005.

Diagnosis. A moderately large Squatina with the following characters: dorsal coloration simple, uniformly greyish brown; two dark subdorsal saddles; anterior ventral surface of pectoral fin blackish; no median row of scute-like denticles on trunk; anterior nasal flap with unfringed barbels; upper lip arch half-oval in shape (lip arch width 3.4–4.1% TL, height 0.9–1.2% TL); interorbital region weakly concave; pectoral–pelvic space 9.4–10.9% TL; pectoral-fin apex angular, not more than 120°; pelvic-fin free rear tips reaching first dorsal-fin origin; tail relatively long, pelvic-fin origin to ventral caudal lobe 3.8–4.0 times pectoral-fin base; pectoral fins moderately long, length 33.5–33.7% TL; dorsal fins not lobe-like; first dorsal-fin base longer than second dorsal-fin base; caudal fin of adult with angular apices; monospondylous centra 50 or 51; total vertebral centra 144.

Description. Body strongly depressed anteriorly, firm; trunk strongly depressed, almost ray-like, deepest at pectoral-fin base; not tapering abruptly at pelvic-fin insertion, tail strongly depressed, even at origin of caudal fin. Abdomen moderately elongate, pectoral–pelvic space 9.4 (10.9)% TL, 0.63 (0.74) of pre-branchial length; pelvic–caudal space 1.38 (1.28) times pelvic-fin length; tail moderately long, height at pelvic insertions 2.06 (2.24) in its width; caudal peduncle strongly depressed, short; lateral keels moderately developed, not greatly expanded anteriorly, originating below insertion of second dorsal fin, slightly below lateral midline, extending about two eye lengths past caudal-fin origin.

Head broad, extended laterally, strongly depressed; oval in cross-section; subcircular, with weakly convex anterior margin when viewed from above (somewhat truncate in large adult male paratype); well-developed dermal folds present along ventrolateral margin of head, no lobes present near mouth corners; head width 19.9 (19.3)% TL, 3.17 (2.28) times head height. Snout very short, bluntly rounded in lateral view, horizontal preorbital length 3.5 (2.9)% TL; elevated slightly between nostril and eye; weak preorbital pit present, barely connected to snout apex by a shallow groove at midline; apex not indented anteriorly. Eye dorsolateral on head, small, suboval, length 2.4 (1.8)% TL, 6.11 (8.13) in pre-branchial length, interorbit weakly concave, no subocular pouches; widely separated, interorbital space 3.23 (4.45) times eye length, 2.26 (2.74) times horizontal preorbital length, 0.85 (0.93) times direct prespiracular length, 3.37 (3.06) times spiracle length. Spiracle of moderate size, cresentic, almost transverse to slightly oblique, well separated from eye, much larger than eye; anterior margin strongly concave, barely elevated above flattened posterior margin; posterior margin almost flat to forming a slight depression leading into spiracle; greatest diameter 3.31 (2.89) in interspiracular space. Gill slits large, pleated, lateral on head, subequal in length, located well forward of midbase of pectoral fin, intergill distance 7.4 (8.6)% TL, 2.68 (2.24) in head width; posterior lateral head fold partly overlapping anterior tip of pectoral fin.

Mouth large, terminal (or very slightly inferior), horizontally expanded, broadly arched, terminating just forward of mid-eye (slightly more posterior in large male paratype), width 12.8 (12.1)% TL, 1.55 (1.59) in head width, 1.62 (1.50) times interorbital space; upper lip forming a broad, moderately convex border with snout; upper labial furrows very large, forming deep preoral groove from symphysis to posterior of jaw angle; lower labial furrows elongate, deep, separated from each other by less than their length; shorter postoral groove very deep, extending parallel to lower labial furrow from jaw angle, length slightly greater than half lower labial furrow length. Teeth widely spaced, unicuspid, small and dagger-like, conical without cusplets on a broad base; upper jaw with 3 small rows on each side of symphysis, midlateral teeth larger (about twice size of symphysial teeth) and more widely spaced than those adjacent; lower jaw edentate at symphysis, lateral teeth evenly spaced, slightly larger than those of upper jaw; no smaller, unpaired teeth at symphysis of upper jaw in holotype (large male paratype with well-developed symphysial teeth); anterior two lateral pairs at symphysis protruding anteriorly when mouth closed (5 rows in paratype); teeth by row in holotype, 18 in upper jaw, 18 in lower jaw, in holotype.

Nostrils large, terminal on head, widely separated, internarial space 5.7 (6.2)% TL, 3.51 (3.12) in head width; adjacent upper lip of mouth. Anterior nasal flap large, overlapping mouth, with two well-developed, unfringed barbels; very large, basally flattened, posterolaterally directed barbel with an irregular membranous tip and large, membranous basal mesial lobe (partly concealed on inner basal edge of barbel); anteroventral margin of flap with a smaller, much more slender, semitubular barbel (capable of being unraveled) with a slightly expanded distal tip, directed mesially; posteroventral margin of nostril with a variably developed, membranous flap, margin sometimes irregular; no nasoral or circumnarial grooves; no dermal lobes.

Dermal denticles covering entire dorsal surface of body, slightly less dense on distal edges of all fins (anterior apex of pectoral fins usually naked). Trunk denticles small, pungent, subconical, strongly raked posteriorly; anterior bases stellate, with clearly defined anterior ridges; similar in size along midline; well-separated, not imbricate; much larger on midline of trunk and tail than on pectoral and pelvic bases; no enlarged, thorn-like denticles on midline; pre- and postorbit with slightly enlarged denticles, much larger and more upright and strongly conical than those on dorsal midline of trunk and tail, more widely spaced than those above midorbit; similarly enlarged patches on postnarial snout. Adult male paratype with partly embedded, malar thorn-like denticles along posteroanterior margin of pectoral fin; denticles slender, spear-shaped, directed posterolaterally or posteriorly; edge of pectoral and pelvic fin anterior margins with dense coverage of minute aspinous denticles (similar to those of ventral surface). Ventral surface largely naked; narrow longitudinal band extending along anterior margin of pectoral fin, sharply demarcated from rest of fin, greatest width slightly larger than orbit diameter; similar but less extensive band around apex of pelvic fin; post-pelvic tail mostly covered with denticles, commencing just anterior of free rear tip of pelvic fins and extending to caudal fin (in adult male paratype, band better developed along pectoral and pelvic fins and tail, width of pectoral band about two eye lengths); denticles very small, dense, partially imbricate, aspinous, crowns circular with entire margins. Claspers of paratype largely naked, large ovoid patches on mid-ventral surface beside free rear tip of pelvic fin. Dorsal and caudal fins mostly with dense coverage of denticles (less so in holotype than adult male).

Pectoral fins very large, expanded, base very fleshy, length 33.7 (33.6)% TL, 1.87 (1.77) times width; anterior margin almost straight to weakly convex, 1.39 (1.44) times inner margin; apex angular, angle slightly less than 120°; posterior margin slightly concave (almost straight in paratype); inner margin very strongly convex, free rear tip broadly rounded. Pelvic fins large, elongate, length 23.2 (24.4)% TL, 1.45 (1.38) in pectoral-fin length; anterior margin convex, apex broadly rounded; posterior margin weakly convex; inner margin almost straight; free rear tip narrowly pointed (more bluntly pointed in paratype), reaching origin of first dorsal fin; pelvic-fin origin anterior to pectoral-fin free rear tip. Claspers of adult male robust, elongate, expanded slightly subdistally, slightly depressed distally with narrowly rounded posterior margin, cartilage at glans opening not sharp-edged, outer margin 5.9% TL, 2.17 times base width. Dorsal fins similar in size and shape (first slightly larger in holotype), strongly raked, close together, height of first 1.06 (1.17) times height of second; anterior margins straight to slightly convex; apices narrowly rounded to somewhat angular, well posterior to fin insertion; posterior margins convex (straight in paratype), directed anteroventrally from top to bottom; inner margin almost parallel to dorsal surface, free rear tip obtuse, broadly rounded; posteriorly located, interdorsal space 1.63 (1.32) times first dorsal-fin base, 0.84 (0.79) times dorsal–caudal space. Caudal fin hypocercal, short, dorsal caudal margin 12.9 (15.2)% TL, 2.48 (2.06) in pelvic–caudal space, height 14.3 (17.0)% TL; lower lobe larger than upper lobe, preventral caudal margin 1.23 (1.06) times dorsal caudal margin; apices somewhat rounded (more angular in adult paratype); dorsal caudal margin almost straight; preventral caudal margin slightly convex; postventral margin strongly notched, deepest slightly above its midlength.

Vertebral counts: monospondylous centra 51 (50); precaudal centra 112 (113); caudal centra 32 (31); total centra 144 (144).

Colour. In preservative: Dorsal surface almost uniformly dark greyish brown; slightly darker over enlarged denticle patches, around eye and on snout; evidence of weak paler blotches on central trunk and tail. Ventral surface almost uniformly white, slightly darker on denticle band along anterior margin of pectoral fin; upper lip dusky; mouth dusky; spiracles pale. Pectoral and pelvic fins similar to body, outer margin pale, almost white; dorsal fins mostly greyish brown, posterior margins translucent; caudal fin similar to body, posterior margin pale to translucent. Adult male paratype (CSIRO H 6565–01) similar to holotype, evidence of blackish subdorsal saddles; margins of pectoral and pelvic fins not white; denticle bands along pectoral and pelvic fins dark, somewhat blackish; darker areas on chin and behind gills; part of tail covered with denticles slightly darker than naked portion. Clasper dorsal surface bicoloured; anterior basal half white; posterior basal half and glans brownish; almost uniformly pale ventrally (denticulated area slightly darker).

Fresh coloration of adult male paratype similar, dark brownish subdorsal saddles much more evident. An additional male specimen (not retained) had similar general coloration but with large, dark brownish blotches and ocelli irregularly scattered over the dorsal surfaces ( Fig. 4 View FIGURE 4 b).

Size. Known from only four specimens, a female of 471 mm TL (holotype), and three adult males of 1252–1341 mm TL (the paratype and two other specimens not retained).

Distribution. Occurs off southern Indonesia. Observed or collected from 4 fish landing sites, Palabuhanratu in West Java (06°59' S, 106°32' E), Cilacap in Central Java (07°44' S, 109°00' E), Kedonganan in Bali (08°45' S, 115°10' E), and Tanjung Luar in Lombok (08°48' S, 116°28' E). Depth information not known.

Etymology. Derived from Greek legnotos meaning ‘having a coloured border’ with reference to the dark anterior edges of pectoral and pelvic fins.

Comparisons. Squatina legnota differs from all Australian angel sharks in having a simple anterior nasal flap with unfringed (rather than strongly fringed) barbels. It also has a less complex color pattern being uniformly coloured apart from its two darker subdorsal saddles (rather than covered with spots, flecks, blotches or ocelli). The scaled anterior ventral margin of the pectoral fin is black (otherwise pale or whitish). Four species of Squatina occur in the western North Pacific: S. formosa Shen & Ting , S. japonica Bleeker , S. nebulosa Regan and S. tergocellatoides ( Walsh & Ebert, 2007) . Squatina legnota does not possess a row of median scutes or spines. Compagno (1984) claimed that all 4 western North Pacific species have a row of spines on the midline of the back and tail, but according to Walsh & Ebert (2007), this state is only present in S. japonica . The three remaining western North Pacific species have different colour patterns to S. legnota . Squatina formosa and S. nebulosa are both covered with black and white spots and appear to have fewer vertebrae (total central 137–139 and 138–139 respectively vs. 144 in S. legnota ). Squatina tergocellatoides , which is known from nearby Borneo ( Yano et al., 2005), has large blackish spots on the pectoral fin and origins of the dorsal fins, but lacks distinct subdorsal saddles. Based on comments by Walsh & Ebert (2007), its pelvic-fin tips and dorsal fin appear to be more widely spaced and it seems to have more ornate nasal barbels. Squatina legnota also possesses more vertebrae than the four species of Squatina from the western North Pacific, i.e. 144 vs. <140, respectively.