Three new legskates of the genus Sinobatis (Rajoidei: Anacanthobatidae) from the Indo – West Pacific
Author
Last, Peter R.
Author
Séret, Bernard
text
Zootaxa
2008
1671
33
58
journal article
10.5281/zenodo.180189
e3efdbf4-b811-4de6-8da6-7701913a1bd1
1175-5326
180189
Sinobatis filicauda
new species
Figs 9–13
;
Table 3
Anacanthobatis
sp. B: Last & Stevens, 1994,
Sharks and rays of
Australia
, pp 357, 359, fig. 35.2, key fig. 4, text figs, pl. 64; Last & Compagno, 1999,
Anacanthobatidae
, leg skates.
In: Carpenter & Niem (eds), 1999, FAO species identification guide for fisheries purposes. The marine living resources of the Western Central Pacific, pp 1466, figs.
Holotype
.
CSIRO
H 948–02, adult male,
548 mm
TL (
341 mm
DW),
678–695 m
depth, Saumarez Plateau, Queensland (
22°56'S
,
154°24'E
), 1985.
Paratypes
.
5 specimens
:
CSIRO
H 1167–04, female,
254 mm
TL (
110 mm
DW),
696 m
depth, Queensland Plateau, W of Lihou Reef and Cays, Queensland (
17°02'S
,
151°03'E
), 1985;
CSIRO
H 1240–02, female,
100 mm
TL (
35 mm
DW),
606–610 m
depth, Queensland Plateau, Queensland (
17°06'S
,
150°52'E
), 1985;
CSIRO
H 2474–01, female,
392 mm
TL (
193 mm
DW) and
CSIRO
H 2476–01, juvenile male,
386 mm
TL (
195 mm
DW),
792–802 m
depth, NW of Lihou Reefs and Cays, Queensland (
17°01'S
,
151°20'E
), 1985;
CSIRO
H 2479–01, female,
508 mm
TL (
368 mm
DW),
880 m
depth, Queensland Plateau, Queensland (
16°55'S
151°34'E
), 1985.
Diagnosis.
A species of
Sinobatis
with the following combination of characters: large disc (width at anterior orbit 5.7–8.1 times mouth width); short tail (postcloacal length 97–140% of disc length); relatively large eyes, orbit diameter
7.1–9.6 in
horizontal snout and
9.4–11.3 in
head lengths respectively; distal portion of tail not expanded, width of tail near tip 0.7–1.1 times tail width at its midlength; pectoral-fin radials 71–75; moderate-sized pelvic fins, anterior lobe 14.8–16.2% TL; anterior pelvic-fin lobe rather broad-based, width
1.6–2.5 in
distance between pelvic-fin origins; caudal fin rudimentary; 18–22 tooth rows in each jaw of adults; teeth of adult males with very short cusps; monospondylous vertebral centra 27–30, total centra 155–182; dorsal surface uniformly pale pinkish brown, ventral surface pale, translucent.
A B
B A B
Sinobatis filicauda
sp. nov.
FIGURE 8.
Oronasal region and tooth bands of
Sinobatis caerulea
sp. nov.
: A, holotype, CSIRO H 2550–10, 539 mm TL, immature male; B, paratype, CSIRO H 2550–01, 684 mm TL, female.
FIGURE 9.
Sinobatis filicauda
sp. nov.
, holotype, CSIRO H 948–02, 548 mm TL, adult male: A, dorsal surface; B, ventral surface.
FIGURE 10.
Sinobatis filicauda
sp. nov.
, paratype, CSIRO H 2479–01, 508 mm TL, female: dorsal surface.
FIGURE 11.
Dorsal view of posterior tail of: A,
Sinobatis bulbicauda
sp. nov.
, holotype, CSIRO H 2557–01, 429 mm TL, adult male; B,
S. caerulea
sp. nov.
, holotype, CSIRO H 2550–10, 539 mm TL, immature male; C,
S. filicauda
sp. nov.
, holotype, CSIRO H 948–02, 548 mm TL, adult male.
FIGURE 12.
Oronasal region and tooth bands of
Sinobatis filicauda
sp. nov.
: A, holotype, CSIRO H 948–02, 548 mm TL, mature male; B, paratype, CSIRO H 2479–01, 508 mm TL, female.
TABLE 3
Morphometric data for the mature male holotype of
Sinobatis filicauda
sp. nov.
(CSIRO H 948–02), with ranges for single male and female (n=3) paratypes. Total lengths (TL) are expressed in mm, other measurements as percentages of TL.
Male Females (n=3)
Holotype
Min. Max.
Description.
Small to medium-sized anacanthobatid with extremely depressed, broad pear-shaped disc (extremely variable between growth stages and between sexes), its width
0.99 in
holotype
(
1.13 in
male
paratype
,
1.15–1.22 in
two female
paratypes
) in length from base of rostral filament; axis of maximum width at 61% (61%, 58–67%) of disc length, outer and inner corners broadly rounded. Tail relatively elongate (when undamaged), very slender, slightly depressed anteriorly; in cross-section, midlength almost flat ventrally, convex dorsally; barely expanded posteriorly, not spatulate; tapering distally to form a slender filament; length much shorter than trunk length, cloaca to tip of tail 1.26 (1.08, 0.95–1.18) in snout-cloaca length (from base of rostral filament), 1.42 (1.06, 0.84–1.07) in disc width, 1.40 (1.20, 0.97–1.31) in disc length;no lateral cutaneous folds. Head moderately elongate, dorsal length 26.6% (27.2%, 27.6–28.5%) TL, ventral length 32.3% (32.0%, 31.7–33.7%) TL. Snout of moderate-sized, its preorbital length 4.10 (5.07, 4.48–5.05) times longer than interorbit, 22.2% (22.6%, 22.3–24.1%) TL; angle forward of spiracles acute, 88° (76–86° in adults and juveniles, 103° in neonate); snout tip with a relatively short, broad, subtriangular rostral lobe; short filament at apex of rostral lobe. Orbits of medium size, horizontal diameter 7.13 (7.89, 8.53–9.56) in preorbital snout length, 1.74 (1.56, 1.69–1.98) in interorbit. Spiracles very small, much less than half length of orbits, subcircular to suboval; combined orbit and spiracle length 4.5% (4.00%, 3.8–4.0%) TL. Mouth weakly convex anteriorly, inner margin of upper jaw weakly concave at symphysis; width 3.87 (5.35, 4.98–5.21) in preoral length, 5.45 (7.08, 6.53) in ventral head length; teeth with an irregular oval base, an elevated, flattened crown and short posterior cusp (less well developed in female and juvenile
paratypes
); cusps enlarged slightly near middle of jaws on male
holotype
. Anterior nasal lobes with weak fringe, barely discernable, confined to anterior lateral margins of nostril; oronasal grooves well developed. Posterior nasal lobes enlarged, weakly connected basally by low, fleshy, concave skin folds; not united medially, not forming a well-defined nasal curtain; lobe with prominent, simple or multifurcate (mostly bifurcate) dermal fringe along posterior margin; not overlapping corners of mouth. Rostral cartilage prominent, flexible, strongly curved. Upper and lower surfaces of disc and tail entirely naked, except for alar thorn patch in adult male
holotype
; patch with 3 rows of sharp, strongly recurved, non-retractable alar thorns; 17–19 thorns on each pectoral fin; thorns directed posteromedially; thorn patch located at level just posterior to apex of fin, length of patch about equal to interorbital distance, width subequal to orbit diameter. Mucous pores on dorsal surface distinct, dark edged (indistinct in
paratypes
), well developed around orbit, 2–3 (2–3) pores lateral to eye and spiracle; damaged (usually 2) pores medial to spiracle, and a single postcranial pore on each side of midline; a few minute tubelike papillae on dorsal surface, barely detectable without magnification; skin thin on dorsal surface, somewhat deciduous, less deciduous ventrally. Anterior margin of disc concave, (most pronounced in
holotype
beside orbit; preorbital margin of
paratypes
almost straight; interspiracular distance 4.88 (5.69, 4.34–5.67) in width at anterior margin of orbit, 3.88 (4.25, 4.09–4.40) in dorsal head length, 2.42 (2.24, 2.58) times orbit diameter; posterior half of disc almost semicircular in females and juvenile
paratypes
; posterior pectoral-fin margins almost uniformly rounded, insertion deeply incised; pectoral axils fused to dorsolateral margin of posterior pelvic-fin lobe well posterior to base of anterior pelvic-fin lobe (fused to margin of posterior pelvic-fin lobe at a point between a half and two-thirds its length in
paratypes
). Anterior lobes of pelvic fins not especially broad, depressed, freely articulating at base, leg-like, well separated from posterior lobes; posterior lobes subrectangular (narrowly suboval in
paratypes
), length 1.03 (0.92, 1.04–1.24) of anterior lobe length, their posterior margins fused to ventrolateral margin of tail just forward of their distal tip. Clasper greatly elongate (extending just short of midlength of tail), suboval, glans distinctly enlarged (adult male not everted); distal lobe minute; pseudosiphon, spur and palp absent; inner dorsal lobe with two shallow proximal clefts; well-developed rhipidion at level of hypopyle; shield very small, inobvious, without pent; sentinel and spike elongate, similar in size and shape, recurved distally, apices pungent; clasper of
holotype
not everted. Caudal fin short, very low, barely detectable, epichordal lobe longer (about or much less than mouth width) than hypochordal lobe. No dorsal fins. Tooth rows in upper jaw 22 (18–21), neonate (CSIRO H 1240–02) with about 14; in lower jaw 22 (20), neonate with about 14. Vertebrae: monospondylous centra 30 (27–29), diplospondylous centra 152 (126–140), total centra 182 (155–167). Pectoral fin: propterygial radials: 23 (24–26), mesopterygial radials 20–21 (18–20), metapterygial radials 29 (29–30), total radials 72–73 (71–75). Pelvic fin: in males 3 + 13 radials (
holotype
CSIRO H 948–02); females 3–4 + 15–16 radials.
| Total length (TL) |
548 |
386 |
254 |
392 |
| Disc width (DW) |
62.2 |
50.5 |
43.4 |
49.2 |
| Disc length |
61.3 |
57.0 |
50.0 |
59.8 |
| Snout - pectoral insertion |
53.9 |
57.2 |
54.6 |
59.6 |
| Snout - axis of maximum width |
37.0 |
34.6 |
33.4 |
34.7 |
| Snout - cloaca |
55.2 |
51.5 |
48.6 |
54.2 |
| Head length (dorsal) |
26.5 |
27.2 |
27.6 |
28.5 |
| Head length (ventral) |
32.3 |
32.0 |
31.7 |
33.7 |
| Snout length (preorbital) |
20.7 |
22.3 |
22.5 |
24.5 |
| Snout - spiracle |
24.6 |
26.7 |
27.2 |
27.7 |
| Snout length (preoral) |
22.9 |
24.2 |
25.3 |
25.7 |
| Prenasal length |
19.2 |
21.7 |
22.4 |
24.0 |
| Orbit diameter |
2.8 |
2.9 |
2.5 |
2.6 |
| Orbit and spiracle length |
4.5 |
4.0 |
3.8 |
4.0 |
| Spiracle length |
1.2 |
0.6 |
0.5 |
0.6 |
| Distance between orbits |
4.9 |
4.5 |
4.4 |
5.0 |
| Distance between spiracles |
6.8 |
6.4 |
6.5 |
6.7 |
| Mouth width |
5.9 |
4.5 |
4.9 |
5.2 |
| Distance between nostrils |
6.0 |
4.7 |
4.2 |
4.7 |
| Head width (at anterior margin of orbits) |
33.4 |
36.4 |
29.2 |
36.8 |
| Nare - mouth |
4.5 |
2.3 |
2.2 |
2.7 |
| Nasal curtain length |
3.3 |
2.6 |
2.0 |
2.3 |
| Nasal curtain width |
7.4 |
6.2 |
5.4 |
5.9 |
| Nasal curtain lobe width |
2.4 |
1.8 |
1.4 |
1.8 |
| Width of first gill opening |
0.8 |
0.7 |
0.5 |
0.7 |
| Width of third gill opening |
0.9 |
0.7 |
0.4 |
0.7 |
| Width of fifth gill opening |
0.6 |
0.4 |
0.3 |
0.5 |
| Distance between first gill openings |
11.8 |
11.2 |
11.5 |
11.7 |
| Distance between fifth gill openings |
7.5 |
7.2 |
7.2 |
7.2 |
| Clasper (post cloacal length) |
18.0 |
5.7 |
0.0 |
0.0 |
| Anterior pelvic lobe length |
16.2 |
14.8 |
15.4 |
15.4 |
| Posterior pelvic lobe length |
15.7 |
14.0 |
12.4 |
14.8 |
| Pelvic base width |
4.3 |
5.0 |
4.2 |
4.9 |
| Anterior pelvic lobe base width |
2.7 |
2.0 |
2.3 |
2.3 |
| Width across posterior pelvic lobes |
9.4 |
7.9 |
6.6 |
9.0 |
| Cloaca - caudal fin tip |
43.8 |
48.5 |
45.8 |
51.4 |
| Tail width (at insertion of pelvic fins) |
1.4 |
1.0 |
1.0 |
1.0 |
| Tail width (pelvic tips) |
1.1 |
0.8 |
0.8 |
1.0 |
| Tail height (pelvic tips) |
0.8 |
0.8 |
0.8 |
0.9 |
| Tail width (at midlength) |
0.6 |
0.7 |
0.6 |
0.8 |
| Tail width (at filament) |
0.6 |
0.6 |
0.6 |
0.8 |
Colour.
In preservative, upper surface of disc and anterior tail pale greyish pink (
paratypes
paler), white on snout tip, along disc margin, posterior tail, and where skin removed; darker brown around alar thorns; postspiracular pores weakly dark edged (less distinct in some
paratypes
); claspers and anterior lobe of pelvic fin white; eyeballs bluish black, visible beneath skin dorsally. Brownish dorsally before preservation. Ventral surface of disc uniformly pale, strongly translucent (often with pink tinge), viscera and radials clearly visible; tail uniformly pale or white.
Size.
To at least
55 cm
TL (disc width
37 cm
); only adult male
55 cm
TL (disc width
34 cm
); smallest neonatal juvenile
10 cm
TL (disc width
3.5 cm
).
Distribution.
Upper continental slope off Queensland from the southeastern sector of the Saumarez Plateau (
22°58'S
,
154°26'E
) northwards to the Queensland Plateau (
16°54'S
,
151°30'E
), in depths of
606–
880 m
.
Etymology.
Derived from the Latin
filum
(thread) and
cauda
(tail, appendage) with reference to its thread-like tail tip. Known in the vernacular as Eastern Australian Legskate.
FIGURE 13.
Distributional ranges of Australian
Sinobatis
species:
S. bulbicauda
sp. nov.
(light grey),
S. caerulea
sp. nov.
(dark grey),
S. filicauda
sp. nov.
(black). The type locations are given for each species:
S. bulbicauda
(black circle),
S. caerulea
(black star) and
S. filicauda
(white star).
Remarks.
Sinobatis filicauda
resembles
S. bulbicauda
morphologically and in coloration but they are easily distinguished by the shape of the posterior tail which is thin and tapering slightly in
S. filicauda
(width of tail near tip 0.7–1.1 times width at midlength) and expanded laterally in
S. bulbicauda
(width of tail near tip 1.3–2.2 times width at midlength). The species also appear to vary slightly in some body ratios. For example, the interorbital width in males is 1.6–1.7 (vs.
1.1–1.6 in
S. bulbicauda
) times and in females 1.7–2.0 (vs. 1.4– 1.7) times the orbit diameter, and the horizontal preorbital length in males is 7.1–7.9 (vs. 4.7–6.6) times and in females 8.5–9.6 (vs. 4.9–8.8) times the orbit diameter.
Sinobatis filicauda
has more pectoral radials than
S. bulbicauda
(72–77 vs. 68–71), and has a relatively smaller head (ventral head length 32–34% vs. 38–42% TL) and paler disc than both
S. caerulea
and
S. melanosoma
(pale brownish dorsally and pale translucent ventrally vs. dark on both surfaces) and is never bluish on the dorsal surface. It reaches a larger size than
S. borneensis
.