Maculabatis ambigua, Last, Peter R., Bogorodsky, Sergey V. & Alpermann, Tilman J., 2016

Last, Peter R., Bogorodsky, Sergey V. & Alpermann, Tilman J., 2016, Maculabatis ambigua sp. nov., a new whipray (Myliobatiformes: Dasyatidae) from the Western Indian Ocean, Zootaxa 4154 (1) : -

Maculabatis ambigua sp. nov.

( Figures 1–8 , Table 1 )

Himantura gerrardi (non Gray): Bogorodsky et al., 2014: 411 ( Saudi Arabia off Jizan). Himantura sp. 1: Last et al., 2016, fig. 3 (figure).

Maculabatis sp. 1: Last et al., 2016, fig. 5 (figure).

Holotype. SMF 35803 (tissue sample KAU14-227), immature male 492 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°51’ N, 42°25’ E, depth 20–22 m, coll. Bogorodsky S.V., Alpermann T.J, Mal A.O., Gabr M.H., 1 Nov 2014.

Paratypes. 12 specimens. CSIRO H 7993-01 (KAU13-654), immature male 262 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°58’ N, 42°26’ E, depth 16–19 m, coll. Bogorodsky et al., 29 Jun 2013 ; CSIRO H 7994-01 (KAU14-228), female 412 mm DW, collected with holotype; CSIRO H 7995-01 (KAU14-436), immature male 234 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°31’ N, 42°31’ E, depth 40–50 m, coll. Bogorodsky et al., 5 Nov 2014 ; KAUMM 0 18 (KAU12-552), female 217 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°45’ N, 42°29’ E, depth 21–28 m, coll. Bogorodsky et al., 1 Mar 2012 ; KAUMM 0 19, immature male 245 mm DW, collected with SMF 34957; KAUMM 0 48 (KAU12-765), immature male 207 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°49’ N, 42°24’ E, depth 47–51 m, coll. Bogorodsky et al., 29 Feb 2012 ; KAUMM 389 (KAU13-656), female 433 mm DW, collected with CSIRO H 7993-0; KAUMM 390 (KAU14-397), female 349 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°36’ N, 42°33’ E, depth 30–32 m, coll. Bogorodsky et al., 4 Nov 2014 ; SMF 34957 (KAU12-717 & KAU12-718), 2 specimens: female 287 mm DW, immature male 352 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°50’ N, 42°26’ E, depth 23–25 m, coll. Bogorodsky et al., 2 Mar 2012 ; SMF 35802 (KAU14-275), female 236 mm DW, Red Sea , Saudi Arabia, off Jizan, 17°02’ N, 42°21’ E, depth 10–12 m, coll. Bogorodsky et al., 31 Oct 2014 ; SMF 35804 (KAU14-229), female 371 mm DW, collected with holotype;

Non-type specimens. CSIRO PRL 1 IMG-6305 (GN 12175), tissue and image only, adult female ~ 840 mm, Zanzibar, Tanzania, coll. Kuguru, B. & Last, P.R., 20 Jul 2012 ; KAUMM 388 (KAU13-655), collected with KAUMM 389; SMF 34958 (KAU12-615), female ~ 240 mm DW, Red Sea , Saudi Arabia, off Jizan, 16°54’ N, 42°22’ E, depth 58–59 m, coll. Bogorodsky et al., 29 Feb 2012 .

Diagnosis. A species of the genus Maculabatis distinguished by the following combination of features: disc rhomboidal with its axis of greatest width well forward, snout tip to maximum disc width 37% (35–39%) DW; preorbital snout short with small apical lobe, rather obtuse, snout angle 121–127°; pectoral-fin apices narrowly rounded, angle 86–92°; orbits moderately small, protruding slightly; mouth relatively narrow, width 6.2–7.0% DW; pelvic fins small, length 17–19% DW, width across base 13–14% DW; preoral snout length 2.8–3.1 times internasal width, 19–21% DW, interorbital distance 2.0–2.2 times orbit length, prenasal length 2.2–2.4 times internasal width; tail behind caudal sting subcircular with longitudinal ventral groove; tail weakly depressed posteriorly with longitudinal lateral ridge on each side in subadults; one enlarged, seed-shaped, suprascapular thorn usually followed by up to five much smaller primary denticles in adults (suprascapular thorn may be preceded by a few much smaller primary denticles in early juveniles); band of secondary denticles suboval (in subadults), very broad (its width across scapulocoracoid much narrower than its width at spiracles), with sharply-defined lateral margins, broad and semi-truncate near tail base; band fully developed and covering entire dorsal surface of tail by 49 cm DW; dorsal surface mainly uniformly brownish, disc margin paler brown dorsally; ventral disc uniformly whitish, not obviously black edged; in subadults, darker dorsal surface of tail sharply demarcated from slightly paler ventral surface (median furrow dark and contrasted with skin adjacent); in juveniles, dorsal post-sting tail with conspicuous, alternating, black-and-white saddles that persist nearly to tail tip, ventral tail uniformly greyish; pectoral-fin radials 130–135; total vertebral count (excluding first synarcual centra) 108–116, monospondylous centra 44–46, pre-sting diplospondylous centra 64–67.

Description. Disc rhomboidal, width 1.11 times length in immature male holotype (1.08–1.11 in the five largest paratypes, 245–412 mm DW) and moderately depressed, raised slightly at mid-scapular region (more pronounced in largest specimens), maximum thickness 11% (9–11%) of DW; preorbital snout moderately short, with small medial lobe at its tip; snout angle 122° (121–127°), anterior angle of disc 109° (106–110°), pectoral angle 92° (86–91°) (no obvious ontogenetic or sexual variability); anterior margins of disc almost straight (weakly concave in juveniles), apices narrowly rounded rather than angular, posterior margins broadly and evenly convex, free rear tip narrowly rounded. Pelvic fins subtriangular, short, length 18.9% (17.1–18.0%) DW; lateral margin almost straight, apex narrowly rounded; free rear tip broadly rounded, combined with inner and posterior fin margins to form strongly convex edge; width across pelvic base 13.5% (12.7–14.1%) DW. Claspers of adult male not observed; distance from cloaca origin to sting 0.44 (0.39–0.44) of disc length. Tail slender, long, whip-like; tapering very gradually and evenly toward caudal sting, then with very weak taper beyond sting to tail tip; its length 2.4 (2.1–2.5) times DW; base narrow, weakly depressed, typically suboval in cross-section, its width 1.33 (1.33–1.59) times its height at base (similar in juveniles); cross-section of tail below sting subcircular in juveniles, more pentagonal in largest types with moderate longitudinal ventral groove; deep dorsal groove housing caudal sting not persistent beyond sting tip in holotype; in subadults, posterior tail slightly depressed, its dorsal surface strongly convex, ventral surface almost flat, lateral edges subangular; juveniles similar, but with less angular lateral edges. Caudal stings moderately elongate, two in holotype (length of first 13.2% DW, second 22.2% DW); one morphometric paratype has two caudal stings with the second sting longest (17.2% DW), other paratypes with one or none.

Snout moderately short, depressed; preoral snout length 3.28 (2.98–3.29) times mouth width, 3.03 (2.76–3.12) times internasal width, 20.3% (19.1–21.3%) DW; direct preorbital snout length 1.63 (1.31–1.71) times interorbital distance; snout to maximum disc width 35–39% DW; interorbital space almost flat; eye small, its diameter 1.84 (1.63–1.99) in spiracle length, protruding slightly (more so in specimens smaller than 22 cm DW); orbit diameter 1.06 (1.05–1.22) in spiracle length, interorbital distance 2.17 (1.96–2.24) times orbit, intereye distance 3.03 (3.05– 3.43) times orbit. Spiracles large, subrectangular to sickle-shaped, situated dorsolaterally; extending forward almost to mid-eye. Nostrils narrow, slightly oblique, outer margin weakly convex; internasal width 2.25 (2.24– 2.36) in prenasal length, 1.80 (1.78–1.98) times nostril length. Nasal curtain relatively narrow, length 5.1% (4.7– 5.4%) DW, width 1.83 (1.68–1.91) times length; lateral margin almost straight, directed posterolaterally, smooth edged; apices narrowly rounded, lying within oronasal groove; posterior margin very finely fringed, weakly double concave (usually expanded slightly medially).

Mouth small, width 6.2% (6.3–7.0%) DW, 1.08 (1.01–1.11) in internasal width; jaws arched strongly; upper jaw strongly double concave, positioned dorsally to lower jaw; lower jaw concave near symphysis, slotting into expanded symphysial knob of upper jaw; oronasal groove broad, deep; skin along margin of lower jaw moderately corrugated, particularly so around lower lip. Mouth floor (in paratypes SMF 34957 and KAUMM 019) with two, well-developed median papillae, a smaller papilla near each corner of mouth; papillae simple, slender, elongate. Teeth of paratype (KAUMM 019) small, subequal in size in upper and lower jaws; rhombic with flattened crowns in upper jaw, smaller with ridged crowns in lower jaw. Tooth rows (paratype KAUMM 019) ~ 36 in upper jaw (holotype not dissected).

Gill opening margins moderately S-shaped, smooth-edged; length of first gill slit 1.24 (1.19–1.60) times length of fifth, 2.48 (1.95–2.39) in mouth width; distance between first gill slits 2.57 (2.59–2.68) times internasal distance, 0.43 (0.43–0.46) of ventral head length; distance between fifth gill slits 1.58 (1.56–1.66) times internasal distance, 0.26 (0.26–0.28) in ventral head length.

Holotype Paratypes

Ranges ......continued on the next page Holotype Paratypes

Ranges Squamation. Developmental stages (definitions of ontogeny following Manjaji, 2004) 0, 1, 2, and 4, evident from type series; stages 3, 5 and 6 appear to be inapplicable. Main denticle band very well developed in 840 mm DW female ( CSIRO PRL1IMG-6305); band elongate and broadly oval, broadest beside spiracle; its margin extending well forward of eyes and convex anteriorly; its posterolateral margin broad, posterior margin weakly convex; band somewhat truncate before tail. No enlarged true thorn-like denticles on disc or tail, apart from prominent seed-shaped suprascapular thorn (length 4–5 mm); distance from posterior end of spiracle 19.1% (19.0– 20.4%) DW in measured types. Denticle band developing rapidly with growth; tail with some scattered post-sting denticles in young (> 260 mm DW); band beginning to extend onto tail at about 350 mm DW. Development of secondary denticle band coincident with raising of central disc; a few small primary denticles sometimes located posteriorly to main seed thorn (4 in holotype with second and third side by side).

Stage 0: early juvenile KAUMM 0 48 (KAU 12-765, 207 mm DW, smallest specimen with evidence of umbilical scar) –– Disc entirely smooth, apart from narrow, seed-shaped mid-scapular thorn (~ 4 mm long); evidence of single primary denticle on nape (presumably absent in smaller juveniles).

Stage 1: juvenile (smallest 210–240 mm DW) –– Primary median denticle band forming on nape (short), well separated from seed thorn; usually no denticles beside seed thorn, single denticle located near posterior edge of seed thorn in CSIRO 7995-01 (KAU 14-436, 234 mm DW).

Stage 2: (ca. 235–290 mm DW) –– Development of secondary denticle band rapid, emerging in SMF 35802 (KAU 14-275, 236 mm DW. An immature male CSIRO 7993-01 (KAU 13-654, 262 mm DW) and immature female SMF 34957 (KAU 12-717, 287 mm DW) with well-developed, trapezoid denticle band, extending from just posterior to spiracles to mid-lumbar region (widest just forward of mid-scapular region and slightly narrower than interspiracular space).

Stage 4: (> 350 mm DW) –– Secondary denticle band well-developed, broad, with well-defined margin; continuous along trunk from just forward of orbit, converging beside pectoral-fin insertions and barely extending onto anterior part of tail in SMF 34957 (KAU 12-718, 352 mm DW); margin of band sharply defined but somewhat irregular, indented slightly over gills and immediately posterior of scapulocoracoid, not extending laterally beside eyes. Subadult CSIRO H 7994–01 (KAU 14-228, 412 mm DW) both with well-developed denticle bands (width at scapulocoracoid up to 27% DW); band broadest beside spiracles and extending well onto side of head lateral to eyes; band semi-truncate beside pectoral-fin insertions and extending over dorsal and lateral tail to caudal sting; dorsal half of post-sting tail of holotype covered with fine denticles, but denticles sparse or absent on ventral surface. No denticles or thorns outside secondary band on disc (stages 5, 6). Denticle band of largest adult ( CSIRO PRL1IMG- 6305, 840 mm DW) similar.

Holotype SMF 35803 (492 mm DW) at Stage 4, secondary denticle band irregularly suboval, with welldefined lateral margins; band extending from well forward of preorbit and onto tail, its maximum width (beside anterior spiracle) much wider than at scapulocoracoid; band not extending onto orbital membrane but present laterally beside eye (its width about equal to orbit length); band semi-truncate posteriorly on disc with convex posterior margin; mid-scapular thorn single (length ~ 4 mm); outer disc, pelvic fins and ventral surface of disc naked; longest caudal sting elongate, ~22% DW, narrow-based, very slender; posterior-most caudal sting better developed than dorsal sting. Dorsal tail to its mid-length uniformly covered with small denticles; denticles becoming sparser towards tail tip. Ventral tail before sting largely naked but denticle band encroaching along ventrolateral surface; band more widespread beneath caudal sting (only ventral groove naked); tail posterior to caudal sting largely naked (apart from ventrolateral edges anteriorly). Denticles largest on mid-belt of disc, particularly near mid-scapular region; crowns flat, varying in shape from ovate to heart-shape; compact, closely-set to form hard band, consisting of interspersed small- and large-size denticles (not imbricated); decreasing in size towards tail tip and toward lateral margins of main band. Disc naked lateral to denticle band.

Meristics. Pectoral-fin counts (n= 2 paratypes): total radials 130–135 (128 on one side of a paratype is probably erroneous), propterygial radials 49–50, mesopterygial radials 20–22, metapterygial radials 60–64. Pelvicfin radials: 1, ~18–21. Vertebral centra: total (excluding 1st synarcual) 108–116, monospondylous 44–46, pre-sting diplospondylous 64–67, and no post-sting diplospondylous centra.

Coloration. When fresh (based on photograph of holotype SMF 35803 and several paratypes). Dorsal disc dark brown with much paler broad brownish margin (broadest near pectoral-fin apices), no dark or pale markings; pelvic fins similar to outer disc; denticle band greyish brown and highlighted from rest of disc; mid-scapular thorn and associated primary denticles white. Ventral surface of disc and pelvic fins uniformly white with narrow dark outer margin. Tail similar to disc, greyish brown dorsally, not banded beyond caudal sting in adults and adolescents; tail of juveniles with whitish saddle-like markings dorsally extending to lateral surface and diffuse ventrally; lengths of pale dorsal saddles subequal to lengths of dark interspaces; ventral surface of adult tail pale brown; caudal stings pale grey. In preservative. Holotype, similar to colour when fresh; ventral surface pale creamy brown, white patches on chin, around gills and on belly. Tail similar to disc dorsally, not banded; ventrally, creamy with ventral groove greyish; caudal stings white. Juvenile male specimen (KAUMM 0 19, 245 mm DW) more uniformly medium brown on dorsal disc and anterior tail; upper half of post-sting tail with alternating black and white saddle-like markings; ventral tail uniformly greyish beyond caudal sting; banding pattern persistent in other juvenile paratypes smaller than 352 mm DW.

Size. Medium-sized whipray with largest known specimen, female ~ 840 mm DW. Birth size probably slightly less than 200 mm DW, based on evidence of umbilical scar in smallest paratype (KAU 12-765, 207 mm DW). No information on size of first maturity; all male types are immature.

Distribution and Habitat. Collected at the Mkokotoni market, Zanzibar ( Tanzania) and in the Red Sea off Jizan, southern Saudi Arabia. Specimens from the Red Sea were trawled in shallow water at 10–60 m depths. It is a typical inhabitant of soft substrata.

Etymology. Derived from the Latin ambiguus (uncertain, doubtful) with reference to its uncertain specieslevel uniqueness, as it very closely resembles plain colour morphs of Maculabatis gerrardi from the northern Indian Ocean, and M. randalli from the nearby Persian Gulf but is more closely related to white-spotted members of the genus. Vernacular name: Baraka’s Whipray, in acknowledgement of the efforts of Tanzanian scientist Baraka Kuguru who helped collect data and tissues for this stingray.

Comparisons. Another Maculabatis (i.e. M. randalli ) from the Western Indian Ocean has a plain dorsal disc lacking white spots. The disc angles of Maculabatis randalli given in the description ( Last et al., 2012) are conflicting between the diagnosis and the description (snout angle should be 113° for the holotype, 115–119° for the paratypes; pectoral angle 97° (96–98°). In M. ambigua sp. nov. the snout is more obtuse (angle 122° in holotype; 121–127° for the paratypes) and the pectoral angle more acute 92° (86–91°). Maculabatis ambigua sp. nov. can also be distinguished by the following: shorter disc (length 90–92% vs. 93–98% DW in M. randalli ), shorter snout (horizontal length 14.6–17.4% vs 18.0–21.7% DW), shorter head (length 40–42% vs. 45–47% DW), smaller intergill width (17.2–18.5% vs. 19.9–21.3% DW), and a narrower internasal distance (width 6.7–7.1% vs. 7.9–8.1% DW). The denticle band in adult of M. ambigua sp. nov. is much wider than in adults of M. randalli (extends laterally well beyond spiracles vs. about equal to width across spiracles in M. randalli ).

Another close relative of M. ambigua sp. nov occurs in the northern Indian Ocean. Maculabatis gerrardi typically has a full or partial coverage of white spots (usually present at least on the posterior disc). Apart from colour and very different molecular profiles (see Fig. 7 and also Last et al., 2016, Figs 3 , 5 ), key distinguishing features between the two have not be documented. The species are not known to overlap in distribution. Maculabatis is under revision by one of us (PL) and Mabel Manjaji-Matsumoto.

Remarks. Gohar & Mazhar (1964) recorded Himantura gerrardi from the Red Sea based on two specimens (male 229 cm DW, female 209 cm DW), trawled at 58 m depth near Jubal Island, northern Red Sea. Subsequent authors adopted their record and included the species in lists of Red Sea fishes ( Dor, 1984, as Dasyatis gerrardi ; Goren & Dor, 1994; Golani & Bogorodsky, 2010). Both of Gohar & Mazhar’s specimens had part of the tail missing, but the rest of tail was plain brown without any bands. They also had slightly enlarged denticles on the trunk but lacked a prominent suprascapular thorn. All specimens of M. ambigua have a prominent suprascapular thorn, and the posterior tail has alternating dark and pale bands in small specimens. Bogorodsky et al. (2014) provisionally identified specimens trawled off southern Saudi Arabia as H. gerrardi , and suggested that Gohar & Mazhar’s record was based on a misidentification of H. fai Jordan & Seale, 1906.

Dor (1984) listed Trygon liocephalus Klunzinger, 1871 (holotype ZMB 8083, a female embryo from Al- Qusair, Egypt) in the synonymy of Himantura gerrardi , but Manjaji (2004) and one of us (PL, after examining the holotype), now consider it conspecific with Himantura fai Jordan & Seale, 1906. The younger name is now widely used so an application will need to be made to the ICZN to suppress the use of Trygon liocephalus .

Figures

FIGURE 1. Maculabatis ambigua sp. nov., immature male holotype SMF 35803 (492 mm DW, fresh, Red Sea, Jizan, Saudi Arabia): A. dorsal surface; B. ventral surface of disc.

FIGURE 2. Dorsal surface of Maculabatis ambigua sp. nov.: adult female, not retained (~ 840 mm DW, fresh, Zanzibar, Tanzania).

FIGURE 3. Oronasal region of Maculabatis ambigua sp. nov., immature male holotype SMF 35803 (492 mm DW, fresh, Red Sea, Jizan, Saudi Arabia).

FIGURE 4. Denticles of dorsal mid-disc of Maculabatis ambigua sp. nov.: A. SMF 34958, female ~ 240 mm DW (KAU 12 - 615); B. SMF 34957 (1 of 2), female 287 mm DW (KAU 12 - 717); C. SMF 34957 (2 of 2), male 352 mm DW (KAU 12 - 718).

FIGURE 5. Lateral view of tail at caudal stings of Maculabatis ambigua sp. nov., immature male holotype SMF 35803 (492 mm DW, fresh, Red Sea, Jizan, Saudi Arabia).

FIGURE 6. Coloration on sections of the mid-tail of Maculabatis ambigua sp. nov.: immature male paratype (KAUMM 0 19, 245 mm DW, preserved, Red Sea, Jizan, Saudi Arabia), A. dorsal, B. lateral and C. ventral views; immature male holotype SMF 35803 (492 mm DW, preserved, Red Sea, Jizan, Saudi Arabia), D. dorsal, E. lateral and F. ventral views.

FIGURE 7. Tree resulting from a maximum likelihood analysis of 652 aligned sites of mitochondrial CO 1 sequence using the General Time Reversible Model with accommodation for among site rate variation (GTR + I + G).

FIGURE 8. Map showing type locations of Maculabatis ambigua sp. nov. Star denotes holotype and solid circle paratypes.

Tables

TABLE 1. Morphometric data for the holotype (SMF 35803) and ranges for seven paratypes of Maculabatis ambigua sp. nov. expressed as percentages of disc width (DW).

Disc width (mm)	492	245	412
Total length	312.6	286.1	322.1
Disc length	89.7	90.1	92.2
Snout to pectoral-fin insertion	79.3	79.2	81
Orbit to pectoral-fin insertion	55.7	54.7	57.6
Snout to maximum disc width	36.8	34.9	38.3
Snout to origin of cloaca	73.2	73.6	76.1
Cloaca origin to tail tip	239.4	212.5	247.3
Cloaca origin to caudal sting	39.4	35.1	39.7
Pectoral-fin insertion to caudal sting (horiz)	31.4	29.3	32.3
Disc thickness	10.6	9.4	11
Snout (preorbital) length	20.1	17.3	20.7
Snout (preorbital horiz.) length	16.9	14.6	17.4
Orbit diameter	5.7	5.4	6.2
Eye diameter	3.3	3.2	4
Spiracle length	6	6	7.2
Orbit and spiracle length	8.8	8.5	9.5
Interorbital width	12.3	12.1	13.3
Inter-eye width	17.2	18.6	20.8
Distance between spiracles	16.4	16.8	18.5
Head length	40.1	40.6	41.6