Notoraja longiventralis, Séret & Last, 2012

Séret, Bernard & Last, Peter R., 2012, New deep water skates of the genus Notoraja Ishiyama, 1958 (Rajoidei, Arhynchobatidae) from the southwest Pacific, Zoosystema 34 (2), pp. 319-341 : 337-339

Notoraja longiventralis n. sp.

( Figs 16-18 ; Tables 2, 3)

Notoraja sp. 1 – Séret in Fricke et al. (2011): listed p. 5.

HOLOTYPE. — MNHN 1999-0449 , male juvenile 434 mm TL, Fiji, cruise MUSORSTOM 10, R / V Alis , Fiji, stn CP1361, 18°0’S, 178°53’E, 660/ 666 m depth, 5.VIII.1998, beam trawl.

PARATYPES. — 2 specimens. MNHN 2008-1389 (field number DHS 402, tissue sample ICTI-001495), male juvenile 229 mm TL, MNHN 2008-1388 (field number DHS 401, tissue sample ICTI-001496), newborn male 168 mm TL, SANTO expedition, R / V Alis, Vanuatu, NE Tubula Island, stn AT60, 15°33’S, 167°22’E, 880/ 953 m depth, 3.X.2006, beam trawl.

DISTRIBUTION. — On the insular slopes off the Fiji Islands, and off Tubula Island ( Vanuatu), between 660 and 953 m depth ( Fig. 18 ).

ETYMOLOGY. — From the Latin “longi”, long, and “ventralis”, in reference to the very long anterior lobe of the pelvic fin.

DIAGNOSIS. — A species of Notoraja (probably of medium size) with the following combination of characters: single rudimentary preorbital thorn; dorsal and ventral surfaces of disc entirely velvety, covered with fine denticles; tail long and slender, entirely velvety, without enlarged thorns; lateral tail folds not expanded distally, always narrower than tail width; nasal lobes not greatly expanded, width of nasal curtain 7.6-8.0% TL; mouth relatively broad, its width more than 66% of maximum width of nasal curtain; anterior pelvic-fin lobe longer that posterior lobe; dorsal and ventral surfaces dark, almost uniformly purplish grey; faint whitish spots over pores along the anterior margins of disc; total pectoral-fin radials 64-65, monospondylous centra 26-27, total diplospondylous centra 109-118, total number of centra 135-145.

DESCRIPTION

Disc heart-shaped, 1.13 (1.13) times as broad as long; maximum angle in front of spiracles 92°

(108°); anterior margin very weakly undulate: slightly concave on either side of tip of snout, convex from anterior extension of propterygium to anterior margin of orbit, concave to level of spiracle; outer corner broadly rounded; posterolateral margin moderately convex. Axis of greatest width 58% (61%) of disc length. Preorbital snout length 3.29 (2.62) times orbit length, 3.65 (3.01) times interorbital width; preoral snout length 1.81 (1.94) times internarial distance. Orbit diameter 1.11 (1.15) times interorbital distance, and 1.53 (2.42) times length of spiracles. Nasal lobes not greatly expanded and rounded, posterior margin shortly and flabby, weakly fringed. Mouth wide, width more than 66% of maximum width of nasal curtain. Upper and lower jaws weakly arched.Teeth plate-like, with short cusps arranged in quincunx in juvenile male holotype. Distance between first gill slits 1.60 (1.67) times larger than between nostrils; distance between fifth gill slits 1.07 (1.03) times larger than between nostrils.

Pelvic fins deeply incised with lobes connected by radials and membranes; anterior lobe much longer than posterior lobe, finger-like, tapering with pointed tip; posterior lobe with convex lateral margins, posterior margin crenate due to extension of posterior radials. Tail narrow at base, depressed oval over length; strongly convex dorsally, weakly convex ventrally; tapering gradually posteriorly, becoming very slender toward tip; tail width at axils of pelvic fins 2.49 (2.20) times width at midlength of tail, and 3.00 (4.10) times width at dorsal-fin origin respectively; length from rear of cloaca 1.54 (1.58) times distance from tip of snout to rear of cloaca; width 1.48 (1.61) times height at axil of pelvic fin, and width at first dorsal-fin origin 1.29 times height (1.17); lateral skin folds near anterior third of tail, extending to proximal half of epichordal caudal-fin lobe and slightly broadening distally, its width always much less than tail width. Dorsal fins of similar shape and size; flag-like, moderately tall with an evenly convex anterior margin, slightly convex posterior margin and a pointed tip; interdorsal space short, 29% (13%) length of first dorsal-fin base. Epichordal caudal-fin lobe relatively well developed, separated by short interspace from and distinctly shorter than second dorsal-fin base; hypochordal caudal lobe developed, its height about half of that of epichordal lobe, originating near end of lateral fold, confluent with epichordal lobe. Male holotype entirely covered with fine dermal denticles on both dorsal and ventral surfaces; denticles densely spaced, bristle-like, with an erect, pointed crown. Single rudimentary preorbital thorn (even in juveniles).Tail uniformly velvety; median thorns rudimentary (barely detectable in juvenile male holotype and greatly reduced in smaller juvenile paratypes). Malar and alar thorns not developed in holotype.

Tooth rows in upper jaw 38 of holotype; 35in lower jaw.Pectoral propterygial radials 28-29 in holotype (29 in paratype); mesopterygial radials 11-12 (12); metapterygial radials 25 (24); total radials 64-65(64). Monospondylous centra 27 (26); diplospondylous predorsal centra 79 (72); predorsal centra 106 (98); caudal centra 39 (37); total diplospondylous centra 118 (109); total centra 145 (135).

Colour (in preservative)

Dorsal and ventral surfaces dark purplish grey, faint whitish spots scattered on ventral surface, mainly at level of pores along the anterior margins of disc.

Size

Reaches at least 434 mm TL from holotype juvenile male; newborn at 168 mm TL.

REMARKS

Notoraja longiventralis n. sp. is set apart from the other velcro skates described above by its much darker dorsal and ventral colouration, its unusually long and pointed anterior pelvic-fin lobes which extend beyond the tip of the posterior lobe, and generally longer interdorsal distance and shorter dorsal head length.

Figures

FIG. 16. — Notoraja longiventralis n. sp., holotype (MNHN 1999-0449, male juvenile 434 mm TL): A, dorsal surface; B, ventral surface. Scale bar: 10 cm.

FIG. 18.— Oronasal region of Notoraja longiventralis n.sp., holotype (MNHN 1999-0449, male juvenile 434 mm TL). Scale bar: 1 cm.