Parmaturus nigripalatum, Ebert, 2018

Ebert, David A., 2018, Parmaturus nigripalatum n. sp., a new species of deep-sea catshark (Chondrichthyes: Carcharhiniformes: Scyliorhinidae) from Indonesia, Zootaxa 4413 (3), pp. 531-540 : 533-539

Parmaturus nigripalatum , new species

Indonesian Filetail Catshark (English), Hiu minyak ( Indonesia) ( Figures 2–6 ; Table 1)

Holotype. NCIP 6567 , 548 mm TL, adult male, south of Sumbawa , Indonesia, 9.04o S, 117.92o E, deep water long line, 170–190 m depth, 16 April 2016.

Diagnosis. A moderate-sized species of Parmaturus with combination of characteristics as follows: body slender, soft-velvety skin, dermal denticles on side and upper body tricuspidate; uniformly plain medium brown body coloration; head slightly depress; snout relatively short; mouth curved, upper and lower labial furrows conspicuous with the uppers and lowers of equal lengths; the roof of mouth blackish with darker pores; teeth mainly tricuspidate with greatly elongate median cusps, about 50 rows in both jaws; origin of the first dorsal fin posterior to the insertion of the pelvic fins, pre-first dorsal fin slightly posterior of body mid-length; origin of second dorsal fin posterior to mid-length of anal fin base; pelvic fins origin and vent slightly posterior to midlength; second dorsal fin slightly larger than first; caudal peduncle relatively short, pronounced caudal crests on upper and lower anterior caudal fin margins with enlarged denticles; vertebral counts monospondylous centra 42, precaudal centra 90.

Description. Proportional measurements expressed as a percentage of total length (TL) are provided for the holotype ( Table 1).

Body not tadpole-shaped, flabby, soft, slightly depressed anteriorly, tapering posteriorly from about pelvic fin bases towards caudal fin origin; abdomen longer than head length; pre-pelvic length 49.3% TL and pre-vent length 51.6% TL; pectoral-pelvic space 27.2% TL, 0.8 of head length; pelvic-anal space 1.5 times anal-fin base length ( Fig. 2 ). Head relatively short and broad, length 20.7% TL, width 10.8% TL; slightly depressed, narrowly rounded in lateral view, height 7.2% TL. Snout short, pre-narial length 4.7% TL, 1.1 times eye length; rounded-parabolic in dorsal view, tip moderately rounded, conical in lateral view; preoral length 5% TL, 1.8 in mouth width.

Eyes relatively large, length 4.2% TL, 4.9 in head length, dorsolateral on head, slit-like, not elevated, slightly above lateral midline; interorbital width 0.8 times pre-narial snout length, 3.4 in head length; subocular ridges welldeveloped. Spiracle small, sub-oval, length 14.5 eye length, and set behind and below posterior eye notch. Nostrils well separated, tube-like, internarial length 2.6% TL; anterior nasal flaps triangular, posterior tip expanded, forming a conspicuous lobe, above level with the mouth.

Mouth large, semi-angular, width 9.0% TL, 2.1 times its length, with symphysial notch on both jaws; lower symphysis not reaching upper symphysis ( Fig 3 ). Labial furrows well developed, upper labial furrow almost equal to lower furrow, upper and lower labial furrows length 1.9% TL. Teeth of upper and lower jaws exposed when mouth closed; tricuspidate with enlarged, erect, acutely pointed central cusp flanked by a single smaller cusplet on each side; teeth on upper jaw smaller relative to lower jaw, but otherwise similar shaped; tooth count on upper jaw 52, lower jaw 48; longest teeth adjacent to symphysis, 2–3 rows of shorter teeth at symphysis ( Fig. 4 ); lateral teeth relatively shorter than anterior.

Dermal denticles on side small, tricuspidate, erect, closely spaced but not overlapping, crown-like with a long pointed median cusp, ending in a longitudinal ridge; denticles on head, body and caudal in similar shape; denticles on the lateral trunk with shorter median cusps. Upper and lower caudal crests well developed, dorsal crests extending from mid-dorsal caudal margin to the second dorsal fin insertion, length of dorsal crests 10.8% TL; ventral crests extending well along caudal peduncle from the origin of lower caudal to almost reaching anal fin insertion or just below mid second dorsal base, length of lower crests 9.3% TL. Denticles of caudal crests have similar shape to body denticles but greatly enlarged, consisting of two rows of enlarged denticles directed posterolaterally and one slightly smaller denticles in the middle row ( Fig 5 ); denticles on anterior crests increasing in size posteriorly until the middle of crests and then slightly smaller posteriorly onto mid-dorsal caudal margin; denticles on ventral crests slightly smaller to those on dorsal crests.

Pectoral fins relatively small, lobate, rounded at apex; anterior margin more convex than posterior margin, anterior margin length 9.6% TL, inner margin rounded. Pelvic fins relatively large, semi-oval, apex broadly rounded, rear corner narrowly rounded, length 9.2% TL. Adult claspers relatively short, outer length 5.4% TL, clasper base width 29.8% of clasper outer length, tapering from base to tip, clasper tip angular and pointed. Denticles covering entire ventral surface and almost absent from dorsal surface. Clasper groove beginning from near pelvic insertion, obliquely running from midline to the lateral edge. Lateral fold and cover rhipidion are not well developed or nearly absent. Rhipidion present along the clasper gland with posterior end beside exorhipidion ( Fig. 6 ).

......continued on the next page Dorsal fins subequal in size, first distinctly smaller than second dorsal fin. First dorsal fin moderately high, originating slightly behind pelvic fin insertion, anterior margin slightly longer than first dorsal fin base, narrowly rounded at apex, posterior margin slightly convex, length less than half of anterior margin length; free rear tip narrowly rounded, inner margin straight, inner margin length 31.7% base length. Second dorsal fin high, originating over posterior half of anal fin base, anterior margin slightly convex, narrowly rounded apex, posterior margin almost upright; rear corner of second dorsal almost forming a right angle, free rear tip rounded, inner margin shorter than first dorsal inner margin, only 20.2% of its base length. Anal fin subtriangular, broadly rounded apex, larger than second dorsal fin; anal fin base 10.7% TL, slightly greater to interdorsal space by 1.1 times. Caudal fin relatively short, dorsal caudal margin length 20.5% TL, with ventral caudal lobe moderately developed distally; terminal lobe well developed but relatively small, fan-like with convex posterior margin, terminal caudal margin length 3.5% TL.

Total vertebral counts 130, monospondylous precaudal (MP) vertebrae 42, precaudal Monospondylous vertebrae 90, diplospondylous centra (DP) 48. Transition between the monospondylous and diplospondylous centra behind pelvic fin girdle and over clasper channels.

Coloration. Specimen prior to preservation is plain medium brownish, dorsal side of pectoral fins and posterior of caudal slightly darker, ventral side of pectoral fins with conspicuous dark margin; edges of dorsal, pelvic and anal fins slightly darker, abdomen paler. Roof of mouth is blackish with darker pores. Claspers and pelvic fins are whitish at insertions. After preservation, body and fins are uniformly dark brown.

Size. The only known specimen (holotype) is an adult male 548 mm TL.

Distribution. Known only from south of Sumbawa Island, Indonesia (9o 02’S, 117o 55’E). Possibly occurs more widespread in eastern Indian Ocean waters.

Etymology. The specific name is a combination of the Latin nigri (black or dark) and palatum (roof of mouth) in allusion to the roof of its mouth being a very distinctive blackish colored. The proposed English common name is Indonesian Filetail Catshark and the proposed Indonesian common name is Hiu minyak.

Comparison. Parmaturus nigripalatum new species, can be separated from all other Parmaturus species by a combination of characteristics including a prominent dorsal and ventral caudal crest, well-developed labial furrows with the uppers and lowers of equal lengths, mouth roof blackish with dark pores, position of the first dorsal fin origin, and tooth counts. The new species has distinctly lower total upper and lower tooth counts (52/48) than all other Parmaturus species (>60 uppers and lowers).

The closest geographic congener, and only other Parmaturus species known to occur in Indonesian waters is P. lanatus , which was described from a single juvenile specimen (360 mm TL) collected from the continental slope off Tanimbar Island in the Arafura Sea (Séret & Last, 2007). However, although the new species is an adult male (548 mm TL) it can be easily separated from P. lanatus by several characteristics including tooth counts (52/48 vs 94/92); presence of a crest of enlarged dermal denticles along the upper and ventral caudal margins; presence of prominent upper and lower labial furrow vs rudimentary or absent labial furrows; a first dorsal fin originating more than one-half it body length (53.8% TL) vs originating less than body length (44.4% TL); roof of mouth blackish with darker pores vs grayish; pectoral-pelvic space is considerably longer (27% vs. 17% TL); interorbital width in head length is greater (3.4 vs. 2.6 times); and abdomen length longer than head length (1.3) vs (0.8); and a slightly higher precaudal vertebral count (90 vs 85).

Parmaturus albipenis was described from a single adult male (415 mm TL) collected off New Caledonia (Séret & Last, 2007), but it can be easily separated from P. nigripalatum n. sp. by the absence of an enlarged caudal crest of dermal denticles along the upper dorsal and ventral margins vs presence; a lower precaudal vertebral count (79 vs 90), a much higher upper tooth count (>130 vs 52); a first dorsal fin originating less than one-half its body length (46.2% TL) vs more than half its body length (53.8% TL); dorsal fins similar in size vs second dorsal being noticeably larger; anterior margins of both dorsal fins similar in length vs second dorsal fin anterior margin longer than first; lower labial furrows longer than uppers vs labial furrows of similar length; and a whitish colored mouth roof vs blackish mouth roof.

Parmaturus nigripalatum n. sp. differs from P. albimarginatus, which was described from a single adult male (577 mm TL) collected off New Caledonia (Séret & Last, 2007) by a total upper and lower tooth count that is much lower (52/48 vs 92/92); a slightly lower precaudal (90 vs 95) and total vertebral (130 vs 136) counts; prepelvic length longer (49.3% vs. 46.9% TL); preanal length longer (62.2% vs. 59.1% TL); longer snout-vent length (51.6% vs. 49.7% TL); greater eye height (2.1% vs. 0.5% TL); a longer prenarial (4.7% vs. 3.7% TL); a narrower head width (10.8% vs. 12.9% TL); labial furrows about equal vs lowers longer than uppers; and darker colored posterior margins of dorsal, caudal and anal fins, compared to white margins in P. albimarginatus.

Parmaturus nigripalatum n. sp. differs from P. bigus, described from a single adult female collected off northeastern Australia, south of Saumarez Plateau (Séret & Last, 2007) by a lower upper tooth count (52 vs 120); lower precaudal (90 vs 102) and total (130 vs 144) vertebral counts; shorter precaudal length (75.6% vs. 84% TL); greater first and second fin dorsal bases (6.5% vs. 4.9% TL and 8.6% vs. 7.3% TL); longer first and second dorsal fin anterior margins (8.6% vs. 5.2% TL and 10.8% vs. 9.3% TL, respectively); shorter pelvic-anal space (7.0% vs. 8.1% TL); longer anal fin length (11.5% vs. 9.7% TL); narrower dorsal-caudal space (2.0% vs. 5.7% TL); longer preventral caudal-fin margin (12.4% vs. 7.3% TL); smaller spiracle (0.3% vs. 0.7% TL); wider mouth (9.0% vs. 6.7% TL); near equal length for upper and lower labial furrows compared to lower furrow being considerably longer that upper furrow; and mouth roof color that is blackish compared to the greyish color found in P. bigus. The overall body coloration (after preservation) between the new species and P. bigus is also informative, with former being uniform dark brown with slightly darker dorsal, pelvic and anal fins compared to the uniform plain yellowish brown, with slightly paler fin margins.

Parmaturus nigripalatum n. sp. differs from P. macmillani in the position of the first dorsal origin (54% vs. 42–48% TL); longer snout length (5.0% vs. 3.2–3.7% TL); smaller mouth width (9.0% vs. 10.3–10.8% TL); a shorter interdorsal space (9.5% vs. 10.7–11.2% TL); a shorter pectoral-pelvic space (27.2% vs. 29.4–29.5% TL); a longer pelvic-anal space (7.0% vs. 5.2–5.8% TL); slightly higher monospondylous (42 vs 38) and total (130 vs 124) vertebral counts; and almost equal length of upper and lower labial furrows compared to lower labial furrow much longer than upper in P. macmillani .

Parmaturus nigripalatum n. sp. differs from P. melanobranchus by a first dorsal fin being about equal in size to second dorsal fin vs a noticeably smaller first dorsal fin relative to second; a first dorsal fin originating more than one-half its body length (53.8% TL) vs less than half its body length (45.9% TL); near equal labial furrow lengths vs much longer lower labial furrow; and lower precaudal (90 vs 102) and total (130 vs 140) vertebral counts.

Parmaturus nigripalatum n. sp. differs from P. pilosus by a longer pectoral-pelvic fin space (27.2% vs 21%); second dorsal fin origin above anal fin base vs second dorsal fin origin opposite anal fin insertion; roof of mouth blackish with darker pores vs light without distinctly darker pores; uniform medium brown, slightly lighter on abdomen and with darker fin edges vs uniform reddish above, becoming lighter distally below first dorsal and extending to caudal region, white below along abdomen and laterally along flanks, and without darker markings or fin edges.

Geographically, P. campechiensis is known only from the western Gulf of Mexico, Bay of Campeche, while P. xaniurus is only known from the eastern North Pacific from California, USA to Baja California, Mexico (Ebert et al., 2013). In addition to biogeography, Parmaturus nigripalatum n. sp. can be separated from these two species by a upper and lower total tooth counts (52/48 vs>60/60); higher total vertebral counts (130 vs 109–121); and upper and lower labial furrows near equal in length vs rudimentary ( P. campechiensis ) or shorter upper labial furrows ( P. xaniurus ).

Figures

FIGURE 2. Parmaturus nigripalatum n. sp. holotype adult male 548 mm TL (NCIP 6567) in lateral and ventral views.

FIGURE 3. Ventral view of head of Parmaturus nigripalatum n. sp. holotype adult male 548 mm TL (NCIP 6567).

FIGURE 4. Symphysial teeth of Parmaturus nigripalatum n. sp. holotype adult male 548 mm TL (NCIP 6567).

FIGURE 5. Parmaturus nigripalatum n. sp., close-up of denticles on flank (left) and caudal crests of dorsal caudal margin (right).

FIGURE6. Dorsalview of claspers of preserved specimenof Parmaturus nigripalatum n. sp. holotypeadult male 548 mm TL (NCIP 6567). Abbreviations: AP: apopyle; CG: clasper groove; HP: hypopyle; CRH: cover rhipidion; RH: rhipidion; ERH: exorhipidion.