Himantura randalli Last, Manjaji-Matsumoto & Moore, 2012, sp. nov.
Creators: name: Last, Peter R.
name: Manjaji-Matsumoto, Mabel
name: Moore, Alec B. M.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Elasmobranchii
Myliobatiformes
Dasyatidae
Himantura
Himantura randalli

description: Himantura randalli sp. nov.
Figures 1–6, Table 1
Trygon gerrardi (not Gray): Blegvad, 1944 (in part), 50–51, Plate II figs 2, 2a (brief description, illustrations of 880 mm TL individual and denticle band) (misidentification).
Himantura gerrardi (not Gray): Randall, 1995, 45, fig. 62 (brief description, figure) (misidentification).
Himantura sp. B: Manjaji 2004, 5 (136–144), fig. 5.2.27 (description, key 5 (10).
Dasyatis bennettii (as bennetti) (not Müller & Henle): Assadi & Dehghani, 1997, 212 (diagnosis, illustration of 270 mm DW female) (misidentification).
Holotype. CSIRO H 7254–01, adult male 412 mm DW, Persian Gulf, Sharq fish market, Kuwait City, Kuwait, 29°23 N, 47°58′ E, probably caught off Kuwait in less than 40 m, collected 0 5 Apr 2011.
Paratypes. 5 specimens. BPBM 33201 (2 specimens), female 151 mm DW, female 245 mm DW, Persian Gulf, Kuwait Bay, Kuwait, R/V Bahith, trawl 8–10 m, collected 21 Aug 1985; BPBM 29480, early adolescent male 325 mm DW, Persian Gulf, Bahrain fish market, collected 0 7 Nov 1983; MTUF 20642, female 414 mm DW, Persian Gulf (as Arabian Gulf); CSIRO H 7296–01, female 251 mm DW, Persian Gulf, Sharq fish market, Kuwait City, Kuwait, 29°23′ N, 47°58′ E, probably caught off Kuwait in less than 40 m, collected 13 Apr 2011.
Other material. CSIRO H 6889–01, BW–A6090 (dried, salted tail section, including sting), mature male ca 500 mm DW, Persian Gulf, Fahaheel fish market, Kuwait, 13 Apr 2008; BW–A6091 (tissued, not retained), male ca 490 mm DW, Kuwait, 15 Apr 2008; BW–2113 (tissued, not retained), R/V Flinders, Kuwait, 2 Sep 2002; BW–A6089 (tissued, not retained), female ca 550 mm DW, Kuwait, 16 Apr 2008; BW–A6303 (tissued, not retained), male ca 500 mm DW, Qatar, 12 Apr 2009; BW–A6308 (tissued, not retained), male ca 240 mm DW, Qatar, 13 Apr 2009.
Diagnosis. A medium-sized species of Himantura (to at least 62 cm DW) distinguished by the following combination of features: disc weakly rhomboidal; preorbital snout moderately elongate with weak apical lobe, snout angle 113–119°; pectoral-fin apices rounded, angle 96–98°; orbits small, protrusible; mouth relatively broad, width 0.9–1.2 in internasal width; distance between first gill slits 2.5–2.6 times internasal distance; distance between fifth gill slits times 1.5–1.7 times internasal distance, 27–29% of ventral head length; pelvic-fin base broad, 13–17% DW; tail behind sting of juveniles subcircular with deep longitudinal ventral groove and prominent mid-lateral ridge, weakly depressed in adults; 1–2 (usually 1) small, broadly heart-shaped to seed shaped suprascapular denticles, primary denticle band and thorns absent; secondary denticle band irregularly suboval, relatively narrow (its maximum width across scapulocoracoid barely exceeding its width at spiracles), with well-defined lateral margins, narrowly tapering near tail base; band fully developed and covering entire dorsal surface of tail by 33 cm DW; dorsal surface mainly uniformly coloured (occasionally with dark flecks in specimens smaller than 25 cm DW), disc margin sometimes paler dorsally; ventral disc uniformly whitish, not black edged; in adults, darker dorsal surface of tail sharply demarcated from paler ventral surface; in neonates and juveniles, tail dark with conspicuous white saddles, its distal portion usually almost uniformly dark; pectoral-fin radials 124–129; total vertebral count (excluding 1st synarcual centra) 108–111, monospondylous centra 43–44, pre-sting diplospondylous centra 65–68.
Description. Disc rhomboidal, width 1.02 times length in adult male holotype (1.02–1.08 in the four largest paratypes,> 245 mm disc width, DW); robust, raised at mid-scapular region (more pronounced in largest specimens), maximum thickness 14% (12–17%) of DW; preorbital snout moderately long, with small medial lobe at the snout tip, angle 97° (96–98°) (no obvious ontogenetic or sexual variability); anterior margins of disc almost straight (sometimes weakly concave), apices rounded rather than angular, posterior margins broadly and evenly convex, free rear tip narrowly rounded. Pelvic fins subtriangular, short, length 19.4% (18.5–21.2%) DW; lateral margin almost straight, apex narrowly rounded; free rear tip broadly rounded, combined with inner and posterior margins to form strongly convex edge; width across base 15.4% (13.3–16.8%) DW. Claspers of adult male moderately elongate, stout basally, tapering strongly, depressed slightly; lining of pseudopera smooth; hypopyle short, about 1/3rd of length of clasper outer margin; without prominent anterior notch; distance from cloaca origin to sting 0.38 (0.37–0.43) of disc length. Tail slender, whip-like; tapering gradually and evenly toward sting, then with very weak taper beyond sting to tail tip; its length 1.8 (2.2–2.4 in 3 smallest paratypes, all undamaged) times DW; base relatively narrow, weakly depressed, typically suboval in cross-section, its width 1.47 (1.07–1.45) times its height at base (usually slightly more depressed in juveniles); below sting base in holotype and adult female, subcircular, in juveniles (less than 250 mm DW) somewhat quadrangular; deep dorsal groove housing stinging spine persistent well beyond stinging spine tip, best developed in juveniles; in adults posterior tail slightly depressed, its dorsal surface strongly convex, ventral surface almost flat, lateral edge subangular; juveniles similar, but with a deep longitudinal groove on mid-ventral surface (variable in length, originating beneath or slightly posterior to stinging spine), flanked by low ventral ridges; juveniles also with prominent ridge along mid-lateral edge of tail, originating near stinging spine, extending almost to tip of tail.
Snout moderately elongate, depressed; preoral snout length 2.72 (2.57–3.22) times mouth width, 2.79 (2.69–2.78) times internarial distance, 22.6% (21.9% in all 4 paratypes) DW; direct preorbital snout length 1.75 (1.47–1.63) times interorbital length; snout to maximum disc width 40% (39–43%) DW; interorbital space almost flat; eye small, diameter 1.98 (1.78–2.64) in spiracle length; orbits capable of being protruded, diameter 1.17 (1.11–1.47) in spiracle length, interorbital distance 2.46 (2.31–3.22) times orbit, intereye distance 3.36 (3.21–4.43) times orbit. Spiracles large, subrectangular to oval, situated dorso-laterally. Nostrils narrow, slightly oblique, outer margin with a weak double concavity; internasal distance 2.14 (2.02–2.12) in prenasal length, 2.19 (1.82–2.42) times nostril length. Nasal curtain relatively narrow, width 1.61 (1.65–1.78) times length; lateral margin almost straight, directed posterolaterally, smooth edged; apices narrowly rounded, lying within broad groove; posterior margin smooth or very finely fringed, weakly concave to weakly double concave (sometimes expanded slightly medially).
Holotype Paratypes Neonate Range
Mouth large, width 0.98 (0.92–1.20) in internasal width; profile arched strongly but variably, not obviously more so in adult male holotype than in large females; upper jaw strongly double concave, dorsal to lower jaw; lower jaw concave near symphysis, slotting into an expanded symphysial knob of upper jaw; oronasal groove prominent, deep; skin along margin of lower jaw moderately well-corrugated, confined to narrow strip around lips. Mouth floor with 2 well-developed papillae, situated close together near centre of mouth; papillae simple, slender, elongate. Teeth small, subequal in size in upper and lower jaws; cone-shaped with blunt apices. Tooth rows (in paratype BPBM 29480) 34 in upper jaw, 40 in lower jaw; holotype not dissected.
Gill opening margins moderately S-shaped, smooth-edged; length of first gill slit 1.41 (1.20–1.28) times length of fifth, 2.99 (2.21–2.65) in mouth width; distance between first gill slits 2.46 (2.49–2.62) times internasal distance, 0.43 (0.45–0.47) of ventral head length; distance between fifth gill slits 1.58 (1.59–1.67) times internasal distance, 0.27 (0.29 in all types) in ventral head length.
Squamation. Ontogenetic stages of squamation (definitions following Manjaji, 2004) 0, 2, and 4, evident from type series; no evidence of stages 1, 3, 5 and 6 in this species. Main denticle band well developed in adults; apart from suprascapular denticles, no enlarged thorns-like denticles on disc or tail; denticle development rapid with all stages occurring across a narrow size range; tail with scattered post-sting denticles even in young (> 250 mm DW), with main denticle band extending onto tail at about 320 mm DW; posterolateral series of denticle band on disc converging posteriorly rather than broad and truncate posteriorly. Development of secondary denticle band coincident with raising of central disc.
Stage 0: early juvenile (ca. 150 mm DW) –– Disc entirely smooth, apart from 2 small, broadly seed-shaped to heart-shape suprascapular denticles (anteriormost longest, ca 2 mm long). Primary median denticle band absent (i.e. Stage 1 absent); existence of suprascapular denticles before birth unknown.
Stage 2: (ca. 250 mm DW) –– Initial stages of development of secondary band not available from the type series, presumably rapid. A 245 mm DW female (BPBM 33201 [1 of 2]) and CSIRO H 7296–01 are at late stage 2 with a well-developed denticle band on disc; band commencing immediately forward of orbit and terminating just forward of pectoral-fin insertion, tapering posteriorly, indented immediately behind spiracles.
Stage 4: (> 300 mm DW) –– Secondary denticle band well-developed, narrow, with well-defined margin; extending as a continuous, longitudinal band along trunk from immediately forward of orbit, terminating immediately forward of pectoral-fin insertion or onto anterior part of tail (ca 310 mm DW) but well short of sting; margin sharply defined but slightly irregular, slightly indented over gills, expanded slightly over scapulocoracoid, converging over posterior disc toward tail. A 325 mm adolescent male paratype (BPBM 29480) has a fully formed denticle band extending over full width of dorsal tail to sting; widely spaced; denticles absent from ventral pre-sting tail; post-sting denticles granular, present on all surfaces of tail but much less dense on posteroventral surface of tail near its apex.
Holotype (412 mm DW) at Stage 4, secondary denticle band irregularly suboval, with well-defined lateral margins, band extending from preorbit and onto tail, its maximum width (just posterior to spiracle) barely exceeding its width at spiracles; band not extending onto orbit nor present on suborbit; band narrow (not broadly truncate) posteriorly on disc, converging onto tail; scapular denticle single, small (length ca 4 mm); claspers, pelvic fins and ventral surface of disc naked; stinging spine elongate, ca 22% DW, narrow-based, very slender; ventral-most stinging spine in paratype MTUF 20642 better developed than dorsal sting.
In largest whole paratype (female, 414 mm DW), secondary denticle band extending from just forward of orbits to cover central disc and entire dorsal tail; ventral tail naked in region from its base to level of sting base; naked snout ratio in type series 72% (64–69%) in direct preorbital snout length; band margin convex anteriorly; broadest just behind spiracles, but similar to width across scapulocoracoid; no denticles lateral to spiracle or orbit; margin irregular, narrowing very gradually posteriorly from mid-disc, before continuing to tail; denticle band similar in largest specimens (480–620 mm DW) based on photographs.
Denticles of cranial and scapular regions with flat crowns, varying from ovate to heart-shape; closely-spaced; minute, much smaller than suprascapular denticles; compact, closely-set, uniform in size in young; small- and large-size denticles interspersed (not imbricated) with age; largest along mid-trunk and around tail base, decreasing in size towards tail tip and toward lateral margins of main band; covering entire post-sting tail, minute and densely granular. Disc lateral to denticle band smooth, without obvious denticles.
Meristics. Pectoral-fin counts (n=5): total radials 124–125 (125–128, n=5), propterygial radials 50–51 (49–52), mesopterygial radials 16 (17–20), metapterygial radials 58 (57–59). Pelvic-fin radials: in males 1, 22 (1, 22, n=1), in females 1, 24–25 (n=4). Vertebral centra: total (excluding 1st synarcual) 110 (108–111, n=5), monospondylous 43 (43–44), pre-sting diplospondylous 67 (65–68), and post-sting diplospondylous 0 (0).
Coloration. When fresh (based on photograph of holotype CSIRO H 7254–01). Dorsal surface of disc and pelvic fins greenish grey with a broad pale pinkish outer margin (infused with blood and probably whitish naturally); marginally paler on denticle band; anterior orbit pale; tail similar to central disc before sting, darker greyish to blackish beyond sting, without evidence of paler bands; clasper pale pinkish basally, blackish distally; stinging spine greyish white. Ventral surface white (covered in pinkish areas where bleeding has occurred); tail basal half white, posterior half dusky but distinctly paler than and sharply demarcated from its dorsal surface.
Fresh juvenile male specimen from Qatar (ca 240 mm DW, image only) with uniformly pale yellowish brown disc, pale greyish brown over main denticle band, broadly translucent along the outer disc margin; tail before stinging spine uniformly pale greyish brown dorsally, white ventrally, no white spots along its lateral margin; tail beyond sting much darker, upper half greyish with about 39 white saddles, ventral half uniformly dusky, not penetrated by white saddles. Tail of a foetus (ca 170 mm DW, fresh image only) fully banded with about 42 bands; mother (female ca 590 mm DW, fresh image only) and largest specimen (female ca 620 mm DW, image only) plain coloured on disc without bands or saddles on tail. Adult males (ca 440–490 mm DW, fresh image only) with a plain yellowish of brownish dorsal surface but usually with some scattered white spots on sides of tail after sting; largest males (ca 500 mm DW, fresh image only) without white markings on tail.
In preservative. Holotype largely similar, more brownish dorsally and with narrow dark margin around disc ventrally; two smallest types (BPBM 33201, 151– 245 mm DW) with faded dark brownish specks over entire dorsal disc surface, more so along the trunk and adjacent areas, but absent from disc margins.
Skeletal morphology. The types were not dissected but based on radiographic information, the shape of the neurocranium is that of a ‘typical’ Himantura (Manjaji, 2004).
Size. Birth size around 150–170 mm DW, based on a presumably free swimming individual of 151 mm DW (BPBM 33201, smallest paratype) and an aborted foetus with unpigmented translucent disc, of 170 mm DW (AM, pers. obs.). Based on field data, males mature by approximately 400 mm DW. A 325 mm DW male specimen (BPBM 29480) was determined as being an adolescent (early maturity stage 3), while the 412 mm DW male holotype (CSIRO H 7254–01) was mature (maturity stage 4). Maximum recorded size of females (620 mm DW) larger than that of males (540 mm DW) (AM, pers. obs.); an uncatalogued female specimen in the South African Museum collection (ca 700 mm DW) referred to by Manjaji (2004) is probably not this species.
Distribution. Known from the Persian Gulf (off Kuwait, Bahrain, Qatar and Iran) from where it is possibly endemic. The Persian Gulf, which is mostly shallower than 40 m and rarely exceeds 60 m depth, has soft substrates dominated by sand and mud. Considered to occur in the Gulf of Oman off Oman and off southern Africa (e.g. Randall, 1995; Manjaji, 2004) but these rays appear to be other species (see discussion below).
Etymology. Named after J.E. Randall of the Bishop Museum whose work on the taxonomy of Indo –Pacific fishes is legendary, and who was amongst the first authors to publish a photographic image of this species (as H. gerrardi) in his guide to the fishes of Oman (Randall, 1995). Vernacular name: Arabian banded whipray (based on Manjaji, 2004).
Life history and fisheries. There appears to be some variation in the birth size of H. randalli. An aborted, 170 mm DW unpigmented foetus was observed in July 2002 (AM pers. obs.), but a presumed free-swimming 151 mm DW neonate (BPBM 33201, smallest paratype) was collected in August 1985, both off Kuwait. The smallest individuals recorded in recent commercial landing surveys by one of the authors (AM) in the month of April were notably larger (ca 240 DW), possibly indicating that birth takes place well before April or that small juveniles are either not caught or not landed locally. Sex ratios significantly different from parity in favour of males were recorded in commercial landings in both Qatar in April 2009 and Kuwait in April 2011 (Moore et al., in press). Significant bias towards females was also recorded for Himantura sp. (presumably H. randalli) in research trawls in the central southern Persian Gulf off Iran, in November–December 2007 (Haseli et al., 2010 and Moore, 2011).
None of the specimens in the present study was examined for stomach contents, although 32 stomachs containing food items of ‘ Dasyatis gerrardi’ (probably H. randalli) from Kuwait contained predominantly shrimp (particularly a small sergestid, Acetes sp.), and to a much lesser extent stomatopods (Euzen, 1987).
Records of Himantura gerrardi and Dasyatis bennetti from the Persian Gulf in the last century are either, wholly or possibly in-part, misidentifications of H. randalli. Trygon gerrardi was listed as the most abundant batoid (77.6% of 1119 individuals) in trawl surveys along the Iranian coast in January–April 1937 and 1938 (Blegvad, 1944), and Dasyatis bennetti was found to be the most abundant batoid (36% of 366 individuals) on the Hormuz coast of Iran, easternmost part of the Persian Gulf (Vossoughi and Vosoughi, 1999). Himantura randalli sp. nov. is an important component of landings from gillnet fisheries in Kuwait and Qatar, and was the most commonly recorded batoid in surveys of landings in Qatar in April 2009 (Moore et al., in press). It was also taken in research trawls in Kuwait’s waters in July and September 2002; despite its relatively high abundance there, it is of low commercial value and often dumped (AM pers. obs.).
Comparisons. Of members of the genus Himantura occurring in the western Indian Ocean, H. randalli is most morphologically similar to forms referable to H. gerrardi. However, H. gerrardi is a species complex (White et al., 2006; Last et al., 2010) and the taxonomy and distribution of these forms in the Indo –Pacific are under review by two us (PL & MM). Using molecular analysis (FISHBOL), H. randalli is closest to the Indo –West Pacific whipray H. pastinacoides (Bleeker, 1852) and clusters well away from members of the ‘ gerrardi group’ (Fig 7). These three taxa are also strongly divergent for the ND2 gene (Naylor et al., in press).
Himantura randalli appears to differ from H. gerrardi forms in morphometrics but these differences need further elucidation. For example, H. randalli appears to be a shorter tailed ray (total length 252–319% DW, n=5, our data vs. 339–412%, n=25 and 347–417% DW, n= 6 in two forms of H. gerrardi (Manjaji, 2004). Himantura randalli also appears to have a longer disc (length 92.5–97.7% DW, n=5 vs. 84.3–94.3%, mean 88.3%, n=41 and 86.1–94.3% DW, mean 90.7%, n=6), smaller orbit (length 4.6–5.7% DW, n=5 vs. 5.0–8.4%, mean 6.7%, n=43 and 4.5–8.7% DW, mean 6.8%, n=18), and wider interspace between the first gill slits (length 19.9–21.3% DW, n=5 vs. 15.6–20.4%, mean 17.2%, n=43 and 16.8–19.5% DW, mean 18.0%, n=18).
Young Himantura randalli can be distinguished from juvenile H. gerrardi in having a dark post-sting tail with white saddles that are absent from its tip (vs. banding pattern persistent to the tail tip in H. gerrardi forms), and dorsal disc typically lacking white spots (vs. variably white spotted but rarely plain). Adult H. randalli are also plain dorsally (vs. with persistent white spotting in all but largest adults of H. gerrardi), the tail is dark dorsally and whitish ventrally (vs. banding usually persistent in all but largest adults), and the tail almost uniformly covered in denticles (vs. coverage much weaker with slower development of denticles). Of the other unidentified species tentatively referred to as H. sp. C (Pakistan whipray) and H. sp. D (short-tail whipray), Himantura randalli can be distinguished by a combination of characters: disc shape, squamation (including shape of the suprascapular and tail denticles, and denticle band shape and development), coloration of dorsal disc, and pattern and development of tail banding. Elucidation of this complex will be part of the broader revision of the group.
Remarks. The existence of Himantura randalli was first known to one of the authors (PL) in the 1990s from loaned specimens collected in Kuwait by J.E. Randall. It has frequently been confused locally with H. gerrardi and H. uarnacoides. The commonly used FAO identification guide for the Persian Gulf (Carpenter et al., 1997) includes only H. gerrardi and H. bleekeri (a junior synonym of H. uarnacoides which has not been recorded from the western Indian Ocean). H. uarnacoides is also plain coloured which may have led to confusion between this species and H. randalli. Manjaji (2004) listed two southern African taxa in the synonymy of H. randalli (as H. sp. B) – Dasyatis jenkinsii (not Annandale): Wallace, 1967, 47, fig. 23 (description, illustration of a 437 mm disc width immature male) and Himantura gerrardi (not Gray): Compagno 1986, 139, fig. 30.9 (brief description, illustration of a 190 mm disc width female). However, inspection of new material from South Africa and the results of molecular barcoding, indicate that these forms are not conspecific with H. randalli (PL unpublished data) or H. gerrardi morphs (Naylor et al., in press).
Further investigation is needed to determine the actual distributions of H. randalli and H. gerrardi forms in the western Indian Ocean. In recent surveys of fish markets along the western and southern Persian Gulf, over 900 batoid specimens were recorded, but none was referable to H. gerrardi (Moore et al., in press). However, off the northern coastline of the Persian Gulf in Iranian waters, Assadi and Dehghani (1997, 211–212) presented photographs of a specimen (27 cm DW) consistent with H. randalli sp. nov. (identified as Dasyatis bennetti? from the northwestern Persian Gulf, near Bushehr), as well as a 43 cm DW specimen identified as H. gerrardi (with a reported distribution of both the Persian Gulf and the Gulf of Oman). Plain coloured Himantura were collected during recent elasmobranch surveys off Oman, but none of these is referable to H. randalli based on the results of unpublished CO1 analysis (A. Henderson, Sultan Qaboos University, pers. comm.). The distribution of H. randalli is of special biogeographic and conservation interest given that current data suggests it is limited to the Persian Gulf. This basin was nearly entirely drained and only re-flooded during the Holocene, indicating that H. randalli may be a recently speciated endemic.
description: Published as part of Last, Peter R., Manjaji-Matsumoto, Mabel & Moore, Alec B. M., 2012, Himantura randalli sp. nov., a new whipray (Myliobatoidea: Dasyatidae) from the Persian Gulf, pp. 20-32 in Zootaxa 3327 on pages 21-31, DOI: 10.5281/zenodo.212521