Squatina tergocellatoides Chen, 1963

Theiss, Susan M. & Ebert, David A., 2013, Lost and found: recovery of the holotype of the ocellated angelshark, Squatina tergocellatoides Chen, 1963 (Squatinidae), with comments on western Pacific squatinids, Zootaxa 3752 (1), pp. 73-85 : 74-82

Squatina tergocellatoides Chen, 1963

( Figures 1–6 , Table 1 )

Common name. Ocellated angelshark.

Holotype. THUP 0 0 348, 625 mm TL (original description), 603 mm TL (present study), immature female, Taiwan Strait ( Figure 1 ).

Diagnosis. A squatinid distinct from other WNP squatinids based on a combination of morphological characteristics including dorsal surface with six distinct paired spots with lighter centers, nasal barbels and flaps strongly fringed, and first dorsal fin originating posterior to pelvic fin free rear tips, a condition only found in S.

japonicus; predorsal thorns on back absent on S. tergocellatoides , present on S. japonica ; lateral head folds have two rounded lobes on each side; upper lip arch semi-oval, upper lip arch height (1.1), upper lip arch width (4.1); spiracles relatively large, length about 1.2 times eye diameter, 1.1 times eye-spiracle length, with smooth posterior inner margins; pectoral fins acutely rounded at apices, with large prominent dark spots at anterior and posterior angles; pelvic girdle width relatively short (21.5), about equal to head length (20.9); dorsal fins relatively small, angular, prominent spots at base of each fin, interdorsal space (5.9–6.3) smaller than dorsal caudal space (7.5–7.8); caudal fin lobed, ventral lobe triangular with its length greater than dorsal lobe length, upper postventral caudal margin very long (6.1).

Description. Proportions as percentages of TL for the holotype and two other specimens from Yano et al. (2005) are presented in Table 1 .

Holotype Yano et al. (2005) THUP 0 0 348 MSR 130 MSR 359 ...... continued on the next page Holotype Yano et al. (2005) THUP 0 0 348 MSR 130 MSR 359 ...... continued on the next page Holotype Yano et al. (2005) THUP 0 0 348 MSR 130 MSR 359 Female Male Female First dorsal fin height 5.6 6.3 4.1 First dorsal fin inner margin length 2.4

First dorsal fin posterior margin length 4.0 5.7 4.2 Second dorsal fin length 5.9 6.2 7.6 Second dorsal fin anterior margin length 6.7

Second dorsal fin base length 3.7 4.0 3.4 Second dorsal fin height 5.7 5.6 4.0 Second dorsal fin inner margin length 2.4

Second dorsal fin posterior margin length 4.0 5.0 Caudal fin upper lobe length 12.3 13.7 Caudal fin lower lobe length 14.9

Caudal lower postventral margin length 4.0

Caudal upper postventral margin length 6.1

Caudal subterminal fin margin length 3.4

Body greatly depressed and ray-like, width at pectoral insertions about 0.8 (0.9) times head (5.5–5.7) in precaudal length. Head broad, depressed, width about 4.1 in precaudal length; head about 5.9 times in precaudal length and 1.4 in head width; preorbital space flattened with slight depression, becoming strongly concave between eye orbitals; interorbital length 2.1 in preorbital head folds moderately expanded, with two to three rounded lobes on each side ( Figures 2a, 2b).

Eyes small, oval, length and height diameters about equal; length about 3.9 (3.3–3.6) in preorbital length greater than eye length. Spiracle inner margin smooth, width subequal to eye slightly greater than eye length; interspiracular length subequal to interorbital length; eye-spiracle eye length ( Figure 2a).

Mouth wide, about 4.4 (4.1–5.3) times mouth length, slightly arched, with double folds in front of each angle of lower jaw. Teeth awl-shaped, slightly curved and directed inwards; three functional series in each jaw; tooth counts by row, upper 10–10, lower 10–10, totals 20 upper and lower, no medial teeth at symphysis. Labial furrows extending medially from corners of mouth; upper labial furrow partially covered by dermal folds, slightly longer than lower labial furrow. Exposed upper lip between bases of anterior nasal flaps forming a narrow high, semi-oval arch; upper lip arch width 4.1, and height 1.1% of TL ( Figure 3 ).

Nostrils terminal, separated from mouth by deep furrow, internarial width moderate 6.4 (6.7–7.2)% TL; nostril width 3.2 in internarial width. Nasal flaps large, expanded at tips with moderately strong lobate fringes; flaps extending from dermal folds above mouth; two distinct nasal barbels protruding from nasal flaps; posterior edges of anterior nasal flaps strongly fringed, tips narrowly lobate and not strongly fringed; posterior nasal flaps low, not greatly enlarged ( Figure 4 ).

Dorsal surface covered with rough, tricuspidate denticles; snout, interorbital space, and anterior of spiracles with clusters of small thornlets; mid-dorsal enlarged spines not present, outer margins of all fins smooth; ventral surface smooth with some very fine close-set rough denticles on outer pectoral and pelvic fin anterior margins. Ventral surface of tail covered with close-set imbricate denticles that do not extend to tail base.

Pectoral fins large, originating behind gills, moderately angular in shape, not forming a distinct anterior shoulder; anterior margin mostly straight, extending to acutely rounded lateral apex, length 28.7 (25.0–29.3)% TL and more than three quarters pectoral fin length; angle is more obtuse than right angle; posterior margin slightly concave leading to acutely rounded free rear tip; inner margin convex, approximately half pectoral fin length. Pectoral fin radial count 40.

Pelvic fins broadly triangular, originating anterior to pectoral fin free rear tip; anterior nearly straight, length approximately 2.1 (2.0–2.5) times pectoral fin anterior margin length; base approximately 1.4 (1.1–1.2) times the length of pectoral fin base. Pelvic girdle width between pelvic fin apices moderately broad, 21.5% TL, and about 1.5 times head length. Free rear fin tip tapering posteriorly to acute tip, ending just anterior to first dorsal fin origin; inner margin slightly concave and short, about 2.7 (2.6–2.9) times pectoral fin length. Pelvic fin insertion furrows on ventral surface extends in a narrow ellipse to anterior apogee of vent, vent is within ellipse. Pelvic fin radial count 29.

Dorsal fins small and slightly angular, second dorsal similar in size or slightly smaller than first dorsal; origin of first dorsal fin posterior to pelvic fin tips; interdorsal space is about 0.8 (0.8) of dorsal caudal space; dorsal fin bases about equal in length; dorsal fin margins relatively straight, apices are lobed acutely rounded; posterior margin about 0.6 times length of anterior margin; inner margin approximately 3.5 times the length of anterior margin; first dorsal fin base 1.8 in interdorsal space, and about 2.2 (1.9–2.2) in dorsal caudal space.

Caudal peduncle flattened dorsal-ventrally, with faintly defined longitudinal ridge along each side. Caudal fin triangular in shape, posterior contour concave with lower lobe 1.2 (1.2–1.5) times length of upper lobe; subterminal caudal fin margin slightly more than 0.5 length of upper postventral caudal margin; caudal lower postventral margin slightly convex, approximately 0.7 length of caudal upper postventral margin ( Figure 5 ).

Total vertebrae 137; total precaudal vertebrae 103; monospondylous vertebrae 48; diplospondylous vertebrae to caudal origin 55; diplosondylous precaudal vertebrae to first dorsal fin origin 34.

Colouration. In life, dorsal surface light yellowish brown covered with close-set, small, numerous rounded white spots; fin borders whitish, except at fin bases that are blackish ( Figure 6 ). The most striking feature of this angel shark are the three pairs of prominent large black spots, each with a diameter greater than eye length; two on each pectoral fin at anterior and posterior angle and one on each side near base of tail; another three pairs of lesser defined, spots, one located at based of each dorsal fin and a third spot located laterally on tail about below first dorsal fin. Ventral surface a uniform white to cream colour, margins of pectoral fins and tail similar in colour to dorsal surface. After preservation, colouration fades to a uniform pale yellowish tan, with all major and minor spots becoming indistinguishable. Dorsal and ventral fin borders become greyish after preservation.

Size. Maximum total length to at least 100 cm, with males maturing at about 85 cm TL and females at about 100 cm TL; size at birth is about 30 cm TL.

General Biology. Virtually nothing is known about the biology of this rather distinctive angelshark. It is an inhabitant of outer continental shelves and upper slopes in warm temperate to tropical waters found at depths of about 100 to 300 m. Litter size unknown. It may be caught as bycatch by trawlers and other fisheries operating in the western Pacific, especially around Taiwan and possibly Indonesia, but there is no specific catch information on the species. Qualitative observations by one of us (DAE) at fish markets in Taiwan indicate that demersal bony fishes are a primary prey item of this species.

Distribution. Endemic to the western Pacific from the waters surrounding Taiwan in the north, southwards to northwestern Malaysia, including the South China Sea, and the waters off Hong Kong and Vietnam (Compagno et al., 2005; Yano et al., 2005; Walsh et al., 2011).

Figures

FIGURE 1. Dorsal view of Squatina tergocellatoides holotype, immature female, 625 mm TL (original description), 603 mm TL (present study). Photograph by D. Ebert.

FIGURE 3. Anterior view of head of Squatina tergocellatoides holotype, depicting lip arch and fringed nasal barbels and flaps. Photograph by D. Ebert.

FIGURE 4. Photograph of nasal flap of Squatina tergocellatoides depicting strongly fringed edges. Photograph by W. White.

FIGURE 5. Caudal fin of Squatina tergocellatoides holotype, triangular in shape with lower lobe longer than upper lobe. Photograph by D. Ebert.

FIGURE 6. Photographs of fresh specimens of Squatina tergocellatoides from Hong Kong (A), Vietnam (B) and Taiwan (C) showing variation in colouration and spot patterns between individuals. Photographs by W. White (A) and H. - C. Ho (B & C).

Tables

TABLE 1. Squatina tergocellatoides proportional measurements expressed as a percentage of total length (TL %) for the holotype (THUP 00348) and two additional specimens taken from Yano et al. (2005) from Malaysia.

	Female	Male	Female
Total Length (mm)	603	854	555
Pre-caudal length	85.6	87.2	80.7
Pre-orbital	2.9	2.8	3.2
Pre-spiracle length	7.3	7.4	7.5
Pre-gill length	16.2	12.9	15.9
Head Length	14.6
Pre-pectoral length	17.8	15.7	22.0
Pre-pelvic length	38.1	39.2	38.7
Snout-vent length	44.4	42.2	44.3
Pre-first dorsal fin length	63.3	66.2	61.8
Pre-second fin dorsal length	73.1	75.5	70.6