Raja parva, Last, Peter R. & Séret, Bernard, 2016

Last, Peter R. & Séret, Bernard, 2016, A new Eastern Central Atlantic skate Raja parva sp. nov. (Rajoidei: Rajidae) belonging to the Raja miraletus species complex, Zootaxa 4147 (4), pp. 477-489 : 478-488

Raja parva sp. nov.

( Figs. 1–8 , 10 ; Table 1)

Raja cf. miraletus 2: Naylor et al., 2012a (fig. 2.9, molecular analysis); Naylor et al., 2012b (fig. 73, molecular analysis).

Holotype. USNM 193744 , adult male 371 mm TL, off Monrovia, Liberia, E. Atlantic, demersal trawl, 27 m depth, 4 Nov 1953.

Paratype. USNM 437522 (re-catalogued from USNM 193744 ), female 411 mm TL, same data as holotype.

Other material. SE-11 (not retained), images and tissue GN5932, adult male 350 mm TL, Senegal, 14°42'N, 17°29'W, J. Caira & K. Jensen, 6 Jan 2002 ; SE-12 (not retained), images and tissue GN5933, female 355 mm TL, Senegal, 14°40'N, 17°27'W, J. Caira & K. Jensen, 6 Jan 2002 ; SE-15 (not retained), image and tissue GN5936, female 295 mm TL, Senegal, 14°40'N, 17°27'W, J. Caira & K. Jensen, 7 Jan 2002 ; SE-153 (not retained), images and tissue GN5993, adult male 320 mm TL, Senegal, 14°42'N, 17°29'W, J. Caira & K. Jensen, 5 Jan 2004 ; 8 specimens (not retained, images only), Angola, R. Leslie.

Diagnosis. A small Raja (to about 41 cm TL) with the following combination of characters: disc subcircular, width 57–60% TL, 1.2 times its length; snout angle 91–96°; tail short, length 1.2–1.4 times distance from snout tip to rear of cloaca; tail narrow, width 1.2–1.3 times height at its midlength, 1.1 times at first dorsal-fin origin; preupper jaw length 10–13% TL, 1.5–1.8 times internasal width; ventral head length 24–26% TL; snout length 3–3.8 times interorbital width; orbit diameter 1.06–0.99 times interorbital width; first dorsal-fin height 3.4–3.9 in its base length; long procaudal tail, length from first dorsal-fin origin to tail tip 3.8–4.7 times first dorsal-fin base length, 3.4–3.6 times caudal-fin length (base of epichordal lobe of caudal fin very long); pelvic fins relatively short, length of posterior lobe 17–18% TL, length of anterior lobe 63–72% of posterior lobe; adult clasper relatively large, ~24% TL, connected to pelvic-fin inner margin at ~47% of its length from cloaca; anterior margin of head with denticle bands on both surfaces in adult male; 2 nuchal thorns; well-developed malar thorn patch in adult male; 3–5 thorn rows on tail; total pectoral-fin radials 79–81; trunk centra usually 27–28; predorsal centra usually 75–86; total centra ~128–131; tooth rows in upper jaw 38–46; brown dorsally with faint lighter and darker speckling; pectoral ocelli moderately large, consisting of dark bluish grey spot surrounded by a black and a yellow ring; ventral surface whitish with reddish yellow snout tip and disc margin.

FIGURE 2. Raja parva sp. nov., female not retained, (SE- 12, 355 mm TL, Senegal, fresh, photo Caira lab).

Description. Disc rhombic, 1.19 times wider than long in adult male holotype (1.18–1.22 times in female paratype); maximum snout angle from axis across anterior spiracle 91° (96°); axis of greatest width 60% (54%) of disc length; anterior disc margin mildly undulate (not noticeably more so in adult male) with short and weak concavity near snout tip (not notched at tip of propterygium), slightly convex forward of eyes, and more deeply concave beside spiracles; apex narrowly rounded to abruptly angular; posterior margin strongly convex; free rear tip broadly rounded. Preorbital snout length 2.88 (3.86) times orbit length, 3.04 (3.82) times interorbit; pre-upper jaw length 1.53 (1.81) times internarial distance. Snout moderately elongate, angular; tip very narrowly rounded and lacking a fleshy process. Orbit diameter 1.06 (0.99) times interorbital width. Spiracle small, length 1.90 (1.46) in orbit diameter; curved, extending forward to beneath posterior quarter of orbit. Nostril small, suboval, distorted in types. Anterior nasal flaps greatly expanded but not forming complete nasal curtain; anterolateral margin bordering nostrils tubular, partly concealed beneath mesial margin of nasal flap; posterior lobes of nasal flaps very well developed, produced posterolaterally, with prominent fringe; posteromesial margin of curtain deeply concave; internarial distance 1.79 (1.84) in distance between first gill slits, 0.78 (1.01) in distance between fifth gill slits. Upper jaw narrow, slightly more strongly arched and indented slightly at symphysis in male; lower jaw strongly convex, most pronounced near middle of jaw; lateral teeth partly concealed by lobes of nasal curtain. Teeth of adult male holotype strongly unicuspid with narrow, subcircular bases; arranged in obvious longitudinal rows; medial cusps very elongate, slender, pungent, directed posteromedially near symphysis of upper jaw, directed more posteriorly toward angle of jaw; cusps smallest at symphysis and near corners of mouth; teeth of female in longitudinal rows, crowns broadly rectangular to sub-hexagonal with short, blunt cusps.

Pelvic fins medium-sized, deeply notched; anterior lobe short, margin narrowly irregular at apex, lateral margin entire, inner margin deeply incised; posterior lobe moderately elongate, not noticeably longer in male, length 17.9 (17.1)% TL), apex narrowly rounded, lateral margin convex, inner margin almost straight; connected to lateral margin of clasper at about half length of clasper; anterior lobe 0.63 (0.72) times posterior lobe; clasper relatively large, robust, postcloacal length about 24% TL in holotype. Tail very slender, weakly depressed; relatively broad at base, tapering strongly to first dorsal-fin origin, not expanded at its mid-length; very narrow behind first dorsal fin; width at insertions of pelvic fins 3.02 (2.47) times width at midlength of tail and 3.58 (2.84) times width at first dorsal-fin origin respectively; length from rear of cloaca 1.39 (1.20) times distance from tip of snout to rear of cloaca; anterior cross-section slightly more convex dorsally than ventrally, strongly convex on both surfaces posteriorly; width 2.17 (1.55) times height at insertion of pelvic fin, 1.21 (1.30) times height at midlength, 1.06 (1.14) times height at first dorsal fin origin; lateral tail fold poorly developed, obscure, even narrow below dorsal and caudal fins. Dorsal fins long, low, well separated; first dorsal-fin height 3.88 (3.35) in base length; similar in size, very strongly raked; anterior margins long and convex, apices narrowly rounded to angular; posterior and inner margins united; anterior margins directed strongly posterodorsally; dorsal fins well separated, interdorsal distance relatively long, 1.66 (1.0) in length of first dorsal-fin base; interdorsal space long. Caudal fin very elongate; epichordal caudal-fin lobe very well developed, low and long-based, base length about half of distance from second dorsal-fin origin to tail tip; procaudal tail very long, distance from first dorsal-fin origin to tail tip 22.0 (23.8)% TL, 3.8 (4.7) times length of first dorsal-fin base, 20 (19) times tail width at first dorsal-fin origin; usually truncate (pointed in paratype) distally, its dorsal margin almost straight; well separated from second dorsal fin; hypochordal caudal lobe absent.

Male holotype with prominent thorns around orbit, in alar, malar and nuchal regions, and along tail; smaller thornlets at snout tip; no scapular thorns. Thorns not forming a rosette around eye, preorbit 4, postorbit 2, spiracular 1. Nuchal thorns 2. Malar patch large, very well-developed, beginning near disc well forward of orbit margin and extending to axis of spiracles. Alar thorn patch narrow, in ~3 rows. Tail thorns in 3 main rows (median and dorsolateral rows with 1-2 lateral thorns on each side); median row with 14 thorns, beginning posteriorly to lateral rows; dorsolateral rows 16–17, commencing above pelvic-fin insertion, terminating near origin of first dorsal fin; lateral thorns 1–2, near base of first dorsal fin; interdorsal thorns 3; tail thorns similar-sized, strongly raked, pungent. Skin largely smooth dorsally; dermal denticles in long, narrow marginal band extending along most of anterior disc; no denticles on tail between thorns; some minute denticles on sides of procaudal tail and on dorsal fins; ventral surface with fine denticles over most of preoral snout.

Female paratype with prominent thorns around orbit, and in nuchal region and along tail; smaller thornlets at snout tip. Thorns not forming a rosette around eye, preorbit 3, postorbit 2, spiracular 1. Nuchal thorns 2. Tail thorns in 5 evenly spaced and continuous rows; median row with 11 thorns, beginning slightly posterior to lateral rows; dorsolateral rows 14–16, commencing over pelvic-fin insertion, terminating beneath base of first dorsal fin; lateral rows 13–16, commencing just posterior to pelvic-fin insertions, terminating beneath base of first dorsal fin; interdorsal thorns 5; tail thorns similar-sized, strongly raked, pungent. Skin largely smooth dorsally; dermal denticles confined to small marginal patch along mid-anterior disc; no denticles on tail between thorns; ventral surface with small patch at snout tip, extending along edge of anterior snout.

Tooth rows in upper jaw (counted from radiographs only) ~ 46 in holotype (38 in paratype); lower jaw 39 (42). Pectoral-fin propterygial radials 32 (34); mesopterygial radials 14 (15–16); metapterygial radials 33 (30–31); total radials 79 (79–81). Pelvic-fin radials male 1, 18; (females 1, ~21 on left side). Trunk centra 28 (27); predorsal diplospondylous centra 47 (59); total predorsal centra 75 (86); centra between origins of dorsal fins 16 (17), diplospondylous centra ~103 (~101), total centra about ~131 (~128).

Raja parva Raja cf. miraletus

Holotype Paratype Range

Total length (mm) 371 411 448 593 Disc width 57.1 60.1 58.5 66.3 Disc length (dir) 48.2 50.8 48.8 50.7 Snout to maximum width 29.0 27.2 26.4 27.9 Snout length (preorbital)—dir 10.7 12.9 10.7 12.2 Snout to spiracle 15.8 17.5 - -

Head—dorsal 17.3 19.3 - -

Orbit diameter 3.7 3.3 3.1 4.1 Orbit and spiracle length 5.0 4.5 5.2 5.7 Spiracle length—main pore 2.0 2.3 2.4 2.8 Distance between orbits 3.5 3.4 2.9 3.4 Distance between spiracles 5.5 5.5 5.0 5.3 Distance-snout to cloaca 41.9 45.4 41.2 41.9 Cloaca to D1 36.1 30.8 32.5 37.1 Cloaca to D2 45.3 40.8 42.3 47.3 Cloaca to caudal origin 52.0 47.6 49.9 54.2 Distance-cloaca to caudal fin tip 58.1 54.6 58.1 58.8 Snout length (pre upper jaw) 10.2 12.6 9.7 11.7 Prenasal length 8.7 10.6 8.4 10.0 Head length to fifth gill 24.4 25.5 24.4 25.9 Mouth width 6.8 6.2 6.7 7.8 Distance between nostrils 6.7 6.9 5.9 6.8 Nasal curtain-length 4.6 4.3 4.1 4.8 Nasal curtain-total width 7.9 8.1 6.6 8.2 Nasal curtain - min width 5.0 5.3 - -

Nasal curtain - lobe width 2.0 1.9 2.0 2.2 Width of first gill opening 1.3 1.6 1.1 2.2 Width of fifth gill opening 1.1 1.2 0.9 1.4 Distance between first gill openings 12.3 12.5 11.4 14.5 Distance between fifth gill openings 5.3 7.0 5.8 7.1 Clasper-post cloacal length 24.2 - 10.8 24.3 Length of anterior pelvic lobe 11.2 12.4 10.4 11.3 Length of posterior pelvic lobe 17.9 17.1 17.1 19.6 Pelvic base - width 9.6 11.5 9.6 12.3 Tail at axil pelvic fins—width 4.0 3.7 3.8 4.7

......continued on the next page Raja parva Raja cf. miraletus Holotype Paratype Range

Tail at axil pelvic fins—height 1.9 2.4 2.5 2.7 Tail at midlength—width 1.3 1.5 2.0 2.4 Tail at midlength—height 1.1 1.1 1.3 1.6 Tail at D1 origin—width 1.1 1.3 1.5 1.8 Tail at D1 origin—height 1.1 1.1 1.0 1.2 D1 base—length 5.8 5.0 3.7 5.6 D1—height 1.5 1.5 1.7 2.5 D1 orig to caudal fin tip 22.0 23.8 20.1 23.6 D2 orig to caudal fin tip 12.8 13.8 11.1 14.1 interdorsal distance 3.5 5.0 3.7 5.3 caudal fin length 6.1 6.9 5.0 6.7 Colour. Based on holotype (preserved): Dorsal surface greyish brown with pale cloudy blotches and prominent pectoral ocelli; snout beside rostral cartilage and outer disc margin (from its apex to its free rear tip) semitranslucent; pectoral ocelli with large dark bluish grey spot surrounded by a thinner black ring, intern surrounded by a similar pale yellowish ring (horizontal diameter of marking across outer ring ~ 17 mm); blotches asymmetrical, diffuse-edged, irregular in size; evidence of faint brownish speckling anteriorly; thorns slightly paler than skin adjacent. Ventral surface of disc, tail and claspers almost entirely uniformly whitish, somewhat semi-translucent yellowish on snout and around disc margin; no sensory pores marked with black edges. Dorsal fins brownish translucent, somewhat dusky anteriorly; epichordal fin lobe similar with darker median and distal bars. Paratype (preserved): Dorsal surface similar to holotype but no markings other than pectoral ocelli apparent; pectoral ocelli similar to holotype (horizontal diameter of marking across outer ring ~ 20 mm); yellowish markings less obvious on ventral surface; two dark bands present on epichordal fin lobe. Non-type SE-11 (fresh image): Dorsal surface richer reddish brown than types, covered with small, faint diffuse-edged white and brownish flecks (not evident in types); snout dark reddish brown; pectoral marking coloration similar to holotype. Ventral surface white with yellowish part of outer disc and anterior snout prominently contrasted reddish yellow.

Size. Adult male holotype 371 mm TL; two other adult males imaged and reported as 320–350 mm TL (http:// tapewormdb.uconn.edu/); female paratype, presumably mature at 411 mm TL; no information available for early juveniles.

Distribution. Wide-ranging in Eastern Central Atlantic; Dakar ( Senegal) south to Angola. Type material from Liberia. Depth unknown, but probably inshore because at least some collected specimens taken by gill-net.

Etymology. Epithet based on the Latin word parva (meaning small) and used with reference to the small adult size of this skate compared to most other members of the genus Raja . Vernacular name: African Brown Skate.

Remarks. Further investigation of the molecular data (combining CO1 and NADH2 data) indicated that four species are involved, rather than three ( Fig. 8 ). Raja miraletus appears to be confined to the Mediterranean Sea, and the North-East Atlantic from the Bay of Biscay south to Morocco and Madeira; it is represented in CO1 datasets from Greece, Israel, Italy, Malta and Portugal (Ward, unpubl.). The southernmost form, referable to the resurrected species Raja ocellifera (as R. miraletus ) occurs off southern Africa from South Africa (False Bay to Durban) and Namibia ( Compagno et al., 1989); it is distinguishable from the other taxa in both CO1 and NADH2 analyses. Raja parva sp. nov. is confirmed from Senegal, Liberia and Angola based on images, specimens and molecular data. It probably occurs more widely between Senegal and Angola, but its distribution needs to be better defined. A fourth species needing further investigation, R. cf. miraletus , is confirmed from Mauritania, and Senegal where it is sympatric with R. parva sp. nov.

Raja parva sp. nov. is distinguishable from non-West African members of the R. miraletus complex by its widely separated dorsal fins and longer procaudal length (22–24% vs. 16–19% TL and 20–21% TL in comparative material of R. miraletus and R. ocellifera respectively). McEachran et al. (1989) observed that West African populations differed markedly from those in the Mediterranean and off South Africa based on their longer interdorsal distances (see fig. 4 of their paper) and this pattern was also evident in a higher number of interdorsal centra (usually 15 or more, Fig. 6 of their paper) of their paper. Apart from the morphometry of the posterior tail, R. parva differs from R. miraletus in clasper structure (particularly the dtr1, dtr2, atr1, atr2, atr3 and ventral terminal cartilages), and also has a much higher predorsal tail centra count (usually 52 or more vs. 52 or less; see Fig. 6 , McEachran et al., 1989). Comparative material from Israel of R. miraletus has smaller pectoral ocelli, possibly less well-developed malar thorns and a smoother ventral head. All four specimens of Raja ocellifera from South Africa have a broader disc, broader tail, and well-developed lumbar thorns and single scapular thorns in the smallest specimen (221 mm TL); the pectoral ocelli are very similar in both species. Further resolution of the species complex is work in progress. Off West Africa, Raja parva sp. nov., based on limited data, appears to differ from the morphologically similar R. cf. miraletus by a typically narrower disc (57.1–60.1% vs. 58.5–66.3% TL) and slightly shorter tail (tail length 1.20–1.39 vs. 1.38–1.43 times precloacal length), smaller spiracle (length 2.0– 2.3% vs. 2.4–2.8% TL), and narrower tail (tail width at pelvic-fin insertion 3.02–2.47 vs. 1.77–1.99 times width at its midlength; tail width at first dorsal-fin origin 1.1–1.3% vs. 1.5–1.8% TL). R aja cf. miraletus appears to have a more broadly pointed snout and probably attains a larger size; largest specimen a female 593 mm TL, with adult males 587 and 590 mm TL and a juvenile male juvenile 448 mm TL (male holotype of R. parva adult at 371 mm TL).

Without the advantage of molecular data, observed morphological and anatomical differences in the populations of R. miraletus -like skates in the Eastern Atlantic were considered by McEachran et al., (1989) to be due to clinal variability. However, the hydrography-based hypothesis proposed to explain this variability are likely to be valid. They postulated that an upwelling at Cape Blanco (21°N) may have isolated the Mediterranean population (i.e. R. miraletus ) from Mauritania-Senegal populations (now known to be two species). Similarly, upwelling off Cape Frio (18°S) and the Benguela Current were thought to be responsible for separating the Angolan population (i.e. R. parva ) and South African population (i.e. R. ocellifera ).

Figures

FIGURE 1. Raja parva sp. nov., adult male holotype (USNM 193744, 371 mm TL, Liberia, preserved): A, dorsal surface; B, ventral surface.

FIGURE 3. Raja parva sp. nov., adult male holotype (USNM 193744, 371 mm TL, Liberia, preserved) showing dorsal snout, orbito-spiracular and nuchal regions.

FIGURE 4. Raja parva sp. nov., adult male holotype (USNM 193744, 371 mm TL, Liberia, preserved) showing the oronasal region and tooth bands.

FIGURE 5. Radiograph of the head of Raja parva sp. nov., adult male holotype (USNM 193744), 371 mm TL, Liberia, preserved).

FIGURE 6. Median and dorsolateral thorns at the tail midlength of Raja parva sp. nov., adult male holotype (USNM 193744, 371 mm TL, Liberia, preserved). A. Dorsal view. B. Lateral view.

FIGURE 7. Lateral profile of the dorsal and caudal fins of Raja parva sp. nov., adult male holotype (USNM 193744, 371 mm TL, Liberia, preserved).

FIGURE 8. Neighbour-joining tree based on p-distances derived from an alignment of mitochondrial NADH 2 sequences (1044 sites), after Naylor et al. (unpubl.)

FIGURE 10. Map showing the locations of types of Raja parva sp. nov., in the eastern Atlantic (star represents the holotype, dots the paratypes).