Leucoraja Malm, 1877

Ebert, David A. & Leslie, Robin W., 2019, Leucoraja elaineae sp. nov., a new rough skate (Rajiformes: Rajidae) from the Western Indian Ocean, Zootaxa 4691 (3), pp. 225-234 : 226-232

Genus Leucoraja Malm, 1877

Type species. Raja fulloncia Linnaeus, 1758 , by subsequent designation of Jordan (1919).

Leucoraja elaineae , new species

Elaine’s Skate

Figures 1 , 2 , 3 , 4 , 5 , Table 1

ZooBank under urn:lsid:

Holotype SAIAB 13742 (PCH 80–20) ( Fig. 1 ), 330 mm TL fresh (318 mm TL after preservation), female, off Malindi, Kenya (03° 25’ S; 40° 23’ E), bottom trawl, 484 m, R/ V Fridtiof Nansen, P.C. Heemstra, 11 December 1980.

Diagnosis. Leucoraja elaineae sp. n. can be separated from all other Leucoraja species by a combination of geographic distribution, color patterning, external morphological characteristics, and meristics. The new species has a simple dorsal color patterning of paired white spots and a single distinct ocelli at the mid-base of each pectoral fin, no tail bands or crossbars, dorsal fins that are not confluent, and a predorsal vertebral count (107), and a pectoral fin radial count (77) that differs from other species. The new species can be separated from its closest geographic congeners by a lack of tail bands and crossbars that are present in L. compagnoi and L. wallacei , and a slightly elongated, pronounced, and rather pointed snout (94.7°) vs a short, bluntly angled (>110°) snout for L. compagnoi and L. wallacei . The new species has a higher predorsal vertebral count (107) vs L. wallacei (64–74) and a higher pectoral fin radial count (77) vs L. wallacei (61–64).

Description. Disc inverted heart-shaped ( Fig. 1 ), width 55%TL, 1.1 times as broad as long; maximum angle in front of spiracles 94.7°; axis of greatest width at 60.8% of disc length; anterior margin weakly undulate, weakly concave near snout tip, convex anterior to and alongside eyes, becoming weakly concave to nearly straight at level of spiracles, then slightly concave to nearly straight to maximum width of pectoral fins; outer corners broadly rounded; posterior margin broadly rounded; free rear tip broadly rounded; inner margin strongly convex. Head short, length 19.2%TL, preorbital snout length 2.2 times orbit length, 2.9 times interorbital width; preoral snout length 1.8 times internarial distance. Snout tip slightly elongated, pronounced, tip slightly produced; fleshy process absent ( Fig. 2 ). Orbit diameter 0.8 times interorbital distance. Spiracles relatively small, length 2.1 in orbit diameter; opening ovalshaped. Nostril oval, anterior nasal flap tube-shaped, opened, with enlarged outer margin; inner margin flap weakly lobed, partially obscured by nasal curtain ( Fig. 3 ). Nasal curtain lateral margin weakly lobed at anterior margin of oro-nasal groove, posterior lobe broadly rounded and prominently fringed; internarial width 2.1 times in distance between first gill slits, 1.1 times in distance between fifth gill slits. Mouth width 1.1 times maximum width of nasal curtain. Upper and lower jaws indented and slightly arched on either side of symphysis. Teeth arranged in quincunx, with oval crown and short pointy cusps.

Pelvic fins bilobed, with very short anterior lobe, depressed, slender, rounded at tip with lobes connected by radials and membranes, posterior margin incised; posterior lobe elongate, 17.3% TL, outer margins broadly rounded, acutely pointed at tip, inner margin nearly straight. Tail relatively long, 53.1% TL, relatively broad based, moderately depressed, tapering gradually to tail tip, very slender from first dorsal fin towards tip; width at axils of pelvic fins 1.2 times tail width at pelvic fin tips and 3.1 times width at first dorsal-fin origin respectively; tail length from anterior of cloaca 1.3 times distance from tip of snout to anterior of cloaca; tail width 1.4 times height at axils of pelvic fin and width at first dorsal-fin origin 1.8 times height; lateral skin folds about 34.3% TL, originating at about pelvic fin tips, extending to distal end of tail and fusing with caudal fin.

Dorsal fin of similar shape, subequal in size, anterior margins broadly rounded, posterior margins convex, inner margin very short, free rear tip bluntly rounded ( Fig. 4 ); fin heights similar, bases dissimilar, with first dorsal fin base 0.7 times in second dorsal fin base; interdorsal space very short, 0.6% TL, connected near bases. Epichordal caudal-fin lobe developed, very short and low, separated by narrow interspace from and distinctly shorter than second dorsal-fin base; hypochordal caudal lobe minute, fused with lateral fold, confluent with epichordal lobe ( Fig. 4 ).

Dorsal disc surface covered with fine prickles, more dense and uniform along rostrum, around orbits, and pectoral fins, becoming sparse with bare patches along pectoral and pelvic fin bases, and trunk; rostrum with small patch of thornlets; orbital thorns forming semicurcular rosette, about 8 (3 on preorbit, 3 on midorbit, 2 postorbit) primary thorns, subequal in size; first three in front of eye, followed by 2 midorbit thorns, a short space and a single thorn, last two thorns beside inner margin of spiracle; three very small thornlets along inner spiracle margin ( Fig. 2 ). Nuchal and scapular thorns forming into dense, amalgamated triangular patch, with 6 larger medial and 3 similar sized laterally siutated thorns on each scapular region, with variable sized thorn patch. Mid-disc thorns in 1–3 rows with thorns irregularly spaced; median thorns becoming progressively small relative to lateral thorns. Tail thorns with continuous medial row flanked laterally and in parallel on each side by 1–3 irregular dorsolateral rows, and variable sized thornlets along lateral tail margin; median thorns smaller than lateral thorns; interdorsal thorn absent ( Fig. 5 ). Ventral disc surface and tail smooth, lacking any prickles, thorns or thornlets.

Meristics. Tooth rows in upper jaw 57; tooth series in upper jaw 5; tooth rows in lower jaw 58; tooth series in lower jaw 5. Pectoral propterygial radials 35; mesopterygial radials 14–15; metapterygial radials 28; total radials 77; pelvic fin radials 1+22. Trunk centra 29; monospondylous centra 32; predorsal diplospondylous centra 75; total predorsal centra 107; total diplospondylous centra 117; caudal centra 25; total centra 149. Pseudobranchial folds left 12, right 12.

Coloration. When fresh dorsal surface a uniform reddish brown, except for a slightly darker line situated laterally just behind, and with width less than, branchial region, a large prominent ocellate located near midbase of pectoral fins with diameter approximately that of orbits, and with 7 primary pairs of small white spots and at least 10 pairs of additional small lateral white spots; tail without any bands; dorsal fins similar colored except whitish to translucent posteriorly, and with tail tip black. Ventral surface mostly whitish around mouth, gills and abdominal regions, snout tip very dark, pectoral fins medium brown; pelvic fin edges brownish, tips of anterior fin lobes slightly darker brown, cloaca region dappled brown; tail mostly white, but with dappled brownish gray spots. Four decades after preservation dorsal surface a uniform light yellowish brown with ocellus and larger paired white spots still distinct, but smaller spots faded, less distinct ( Fig. 1a ); tail tip still darkly colored ( Fig. 4 ). Ventral surface similarly colored, but lighter brown disc and pelvic fin edges; tail with browish spots ( Fig. 1b ).

Size. The only known specimen, a female, before preservation measured 330 mm TL, and 40 years after preservation measured 318 mm TL.

Distribution. The new speices is known only from a single specimen from off Malindi, Kenya (03° 25’ S; 40° 23’ E), and at a depth of 484 m.

Etymology. The new species is named in honor of Elaine Heemstra for her enormous contributions in illustrating marine fishes, mostly from the Western Indian Ocean. The proposed common name is Elaine’s Skate.

Figures

FIGURE 1. Leucoraja elaineae sp. n., female holotype, SAIAB 13742, 318 mm TL, after preservation showing a total dorsal view, b total ventral view. Scale bar: 5 cm. Photograph courtesy Marsha Englebrecht ©

FIGURE 2. Leucoraja elaineae sp. n., female holotype, SAIAB 13742, 318 mm TL, after preservation showing snout, orbit, spiracle, and nuchal regions. Photograph courtesy Marsha Englebrecht ©

FIGURE 3. Leucoraja elaineae sp. n., female holotype, SAIAB 13742, 318 mm TL, after preservation showing oronasal region and tooth band. Photograph courtesy Marsha Englebrecht ©

FIGURE 4. Leucoraja elaineae sp. n., female holotype, SAIAB 13742, 318 mm TL, after preservation showing lateral view of dorsal and caudal fins. Photograph courtesy Marsha Englebrecht ©

FIGURE 5. Leucoraja elaineae sp. n., female holotype, SAIAB 13742, 318 mm TL, after preservation showing thorns at tail mid-length in a dorsal view, b lateral view. Photograph courtesy Marsha Englebrecht ©

Tables

TABLE 1. Morphometrics of the holotype of Leucoraja elaineae sp. nov. expressed as % of total length.

Total length (mm)	318
Disc width (%)	55.0
Snout tip to maximum disc width	29.6
Snout to preorbital	11.9
Snout to spiracle (direct)	16.7
Snout to spiracle (straight)	16.4
Snout base width at spiracles	35.5
Head length dorsal	19.2
Orbit, horizontal diameter	5.3
Eyeball, horizontal diameter	3.5
Interorbital width	4.1
Spiracle length: slit	2.5
Spiracle length: depression	3.1
Interspiracle width	6.6
Orbit – spiracle length	6.6
Prenasal length	9.1
Snout to preoral length	13.8
Snout tip to anterior-vent length	42.8
Snout tip to 1 st hemal spine	46.9
Head length ventral	25.8
Internarial width	7.5
Nasal curtain length	4.4
Nasal curtain total width	8.5
(distance from outer of each lobe)
Nasal curtain space between lobes	5.3
(minimum between lobes)
Gill slit length 1 st	1.9
Gill slit length 3 rd	1.6
Gill slit length 5 th	1.3
Interspace first gill slits	15.4
Interspace fifth gill slits	8.5
Pelvic-fin length anterior lobe	12.3
Pelvic-fin length posterior lobe	17.3
Anterior vent to 1 st dorsal fin	43.7
Anterior vent to 2 nd dorsal fin	57.5
Tail post-dorsal length	2.5
Tail height at pelvic fin base end	3.5
Tail width at pelvic fin base end	5.0
Tail height at pelvic tips	2.5
Tail width at pelvic tips	4.1
Tail height at first dorsal fin origin	0.9
Tail width at first dorsal fin origin	1.6
Tail lateral fold length	34.3
First dorsal fin, height	1.9
First dorsal fin, base length	5.7
Second dorsal fin, height	1.9
Second dorsal fin, base length	4.1
Interdorsal space	0.6
Caudal fin base length	1.9
Caudal fin height epichordal lobe	0.6
Caudal fin height hypochordal lobe	0.6
Caudal fin length hypochordal lobe	0.3