Comprehensive DescriptionRead full entry
Parmaturus bigussp. nov.
Figs 6 and 7, Tables 1-3
Beige catshark (English), holbiche beige (French)
Parmaturus sp. A : Last & Stevens, 1994: 204, fig 26.32, pi. 20 (short-tail catshark)
Material. 1 specimen.
Northeastern Australia . South of Saumarez Plateau ( Queensland ), 22°56’S , 154°21’E , 590-606 m depth, 17 November 1985 , FRV “Soela”, lobster trawl, adult female 710 mm TL ( CSIRO H 947.10: holotype ).
Diagnosis. A scyliorhinid catshark with the following combination of characters: a soft body; velvety skin with small tricuspidate denticles; plain pale yellowish brown coloration; fins yellowish brown with slightly paler edges; dorsal caudal crest well-developed, ventral crest distinct but weak, denticles enlarged on crest; teeth mainly tricuspidate, in 120 rows in upper jaw; first dorsal fin slightly behind mid-length, pre-first dorsal length 54.9% TL; pelvic fins slightly forward of mid-length, pre-pelvic length 48.9% TL; vent at middle of body, pre-vent length 50.8% TL; snout relatively short, prenarial length 4.2% TL; mouth short, length 3.6% TL; labial furrows short, lower furrow longer than upper furrow, 1.7% and 1.2% TL respectively; head not depressed, its height subequal to its width, length shorter than abdomen, 19.8% TL; pectoral-pelvic length 25.4% TL; second dorsal fin larger than first, anterior margins of first and second dorsal fins 5.2% and 9.3% TL respectively; subterminal caudal lobe relatively small, subterminal margin length 3.8% TL, terminal margin length 3.6% TL; monospondylous centra 47; precaudal centra 102.
Description. Scyliorhinid catshark with a rather soft body; trunk slightly compressed, tail moderately compressed and tapering slightly to caudal fin; head not depressed, height 9.1% TL, shorter than abdomen; pectoral to pelvic space 25.4% TL, 1.3 in head length; pelvic to anal space 0.8 in anal-fin base. Caudal peduncle low, elongate, anal to caudal space 1.2 of anal-fin base length; moderately compressed, width 1.7 in height, dorsal and ventral profiles longitudinally ridged by anterior part of upper and lower caudal crests. Snout short and narrowly parabolic in dorsoventral view, tip broadly rounded, conical in lateral view; preoral length 5.7% TL, 0.7 in mouth width; prenarial snout 1.2 times eye length. Eyes large, length 3.4% TL, 5.8 in head length; eyes almost lateral on head, with well-developed subocular ridges. Labial furrows short but well developed, right lower furrow longer than upper, 1.7 and 1.2% TL respectively. Nostrils large with tube-like incurrent apertures, anterior nasal flaps sub-triangular, posterior tip expanded, forming a weak lobe; nostrils well separated, internarial length 2.3% TL; nasal flaps well short of front of mouth.
Teeth of upper and lower jaws exposed when mouth closed; anterior teeth mainly tricuspidate, with greatly enlarged median cusp, lateral cusps much shorter; lateral teeth asymmetrical, with relatively smaller median cusps, lateral cusps toward angle of jaw usually reduced or absent, lateral edge towards anterior part of mouth with 1-2 cusps; upper jaw double concave at symphysis, longest teeth adjacent to symphysis, 2-3 rows of very short teeth at symphysis; teeth in lower jaw similar, also with poorly developed lateral cusps toward angle of jaw; tooth bases ridged; in 120 rows in upper jaw; in oblique rows or in quincunx arrangement. Dermal denticles on side small, tricuspidate, weakly imbricate, erect, densely packed; crown shield-like with a long pointed median cusp, ending in a longitudinal ridge; lateral cusps short, variably developed (cf. illustration in Last and Stevens, 1994, p. 204). Upper caudal crest well developed, extending from upper caudal margin to below second dorsal-fin rear corner, in a deep groove near its origin; elevated slightly above rest of fin; lacking a well-defined naked area at its base; denticles at lateral edge of crest mainly directed posterolaterally and slightly ventrally, largest at least twice length of tail denticles; lateral denticles tricuspidate with lateral cusps barely shorter than median cusps, separated by 3-5 rows of smaller denticles. Crest on ventral midline of caudal peduncle originating above anal-fin rear corner, but not extending onto preventral caudal margin; denticles barely larger than those of adjacent tail, some directed slightly laterally (unlike the posterior orientation of those on the flanks).
First dorsal fin much smaller than second dorsal; first dorsal originating slightly forward of pelvic-fin insertion, second originating over posterior half of anal-fin base; anterior margin of both dorsal fins slightly convex, apices rounded; posterior margin of first dorsal fin strongly convex, margin of second dorsal less convex; rear corner of first dorsal fin broadly rounded; rear corner of second dorsal fin acutely angular; inner margins short, straight, directed posterodorsally. Pectoral fin very small, almost subcircular, lobe-like, anterior margin 7.6% TL; all margins convex, apex less rounded than rear corner. Pelvic fin relatively large, semi-oval, apex broadly rounded, length 7.3% TL. Anal fin triangular, slightly lower than second dorsal fin, base 9.7% TL; its base length about equal to interdorsal space; origin below anterior half of interdorsal space, anal-fin height 2.1 in base length. Caudal fin very short, dorsal caudal margin length 20.2% TL; upper and lower lobes originating from caudal crests; lower lobe moderately developed distally; terminal caudal lobe fan-like, bilobed, with a deep median notch. Monospondylous centra 47; precaudal centra 102; total centra 144.
Coloration. (from preserved specimen). Body plain, uniform pale yellowish brown, slightly paler ventrally. Fins similar to body, with slightly paler posterior margins. Floor and roof of mouth greyish, roof with some dark-edged pores.
Size. Known only from the holotype adult female 710 mm TL.
Distribution. Known from near the Saumarez Plateau, 22°56’S, 154°21’E, (northeastern Australia) in 590-606 m depth (Fig. 1).
Etymology. From the Latin “ bigus ” meaning beige in reference to the general plain pale yellowish brown coloration.
Remarks. The holotype had an egg-capsule coming out of the cloaca when caught.
Comparisons. Parmaturus bigus is set apart from all other new Parmaturus ZBK species by its deep, almost subcylindrical head. In comparison, other Indo-Pacific species have a much more depressed head (height only 0.5-0.6 in its width rather than subequal to its width).
Parmaturus albipenis also differs from P. bigus by: caudal crest without enlarged denticles (crest welldeveloped with enlarged denticles in P. bigus ); first dorsal fin forward of mid-length (after mid-length); and a longer subterminal caudal lobe (5.7% TL versus 3.8% TL).
Parmaturus albimarginatus also differs from P. bigus by: a shorter precaudal length (78% TL versus 84% TL in P. bigus ); longer preanal length (about 59% TL versus 52% TL); wider interorbital space (7.7% TL versus5.4% TL); shorter dorsal-caudal space (2.8% TL versus 5.7% TL), and fewer tooth rows (92 versus 120 rows in the upper jaw).
Parmaturus melanobranchus also differs from P. bigus by: first dorsal fin forward of mid-length (after mid-length in P. bigus ); head longer than abdomen (rather than shorter); and a dark brown or grey coloration (pale yellowish brown).
Parmaturus pilosus ZBK also differs from P. bigus by: teeth with 5-6 cusps (versus mainly 3 in P. bigus ); first dorsal fin forward of mid-length (after mid-length); and a longer and deeper subterminal lobe (length 5.5% versus 3.8% TL).
Parmaturus macmillani ZBK also differs from P. bigus by: first dorsal fin forward of mid-length (after midlength in P. bigus ); dorsal fins subequal in size (versus second dorsal larger than first); and 38 monospondylous vertebral centra (versus 47).