Myliobatis tobijei Bleeker, 1854

White, William T., Kawauchi, Junro, Corrigan, Shannon, Rochel, Elisabeth & Naylor, Gavin J. P., 2015, Redescription of the eagle rays Myliobatis hamlyni Ogilby, 1911 and M. tobijei Bleeker, 1854 (Myliobatiformes: Myliobatidae) from the East Indo-West Pacific, Zootaxa 3948 (3), pp. 521-548 : 532-542

Myliobatis tobijei Bleeker, 1854

( Figs. 8–15 , 17 b; Table 2 )

Myliobates aquila (not Linnaeus): Temminck & Schlegel, 1850: 310, pl. 142 ( Japan); Boeseman, 1947: 228 ( Japan); Tokida & Kobayashi, 1967: 180 ( Japan).

Myliobatis aquila (not Linnaeus): Bleeker, 1853: 22 ( Japan); Günther, 1880: 63 (Yokohama, Japan); Pietschmann, 1908: 638 ( Japan).

Myliobatis tobijei Bleeker, 1854: 425 (Nagasaki, Japan): Bleeker, 1855: 130 ( Japan); Bleeker, 1859: 270 (Nagasaki, Japan); Bleeker, 1860: 10 (Nagasaki, Japan); Martens, 1876: 410 (Yokohama, Japan); Jordan & Snyder, 1900: 338 (Tokyo, Japan); Jordan & Snyder, 1901: 43 (Yokohama and Nagasaki, Japan); Jordan & Fowler, 1903: 663 (Tokyo, Japan); Jordan, 1905: 557 ( Japan); Garman, 1913: 433 ( Japan); Jordan & Metz, 1913: 6 (Fusan[=Busan]); Fowler, 1929: 507 ( Japan); Fowler (1930): 186 ( China); Schmidt, 1931: 15 (Nagasaki, Japan);? Fang & Wang, 1932: 277, fig. 27 (Chefoo [=Yantai], China);? Wang, 1933: 113 (Ningpo[=Ningbo], China); Masuda et al., 1984: 16, pl. 19-D ( Japan); Amaoka et al., 1989: 257 (Hokkaido, Japan); Nishida, 1990: 4, figs 9C, 16A, 19D, 28A, 38H, 40B, 57B ( Japan); Miya et al., 1994a: 111 (Central Japan); Miya et al., 1994b: 120 (Chitose, Japan); Miya et al., 1995: 198 (Choshi, Japan); Kitamura et al., 1996: 340 (Tokyo, Japan); Shinohara et al., 1998: 108 (Nagasaki, Japan); Compagno & Last, 1999: 1513, 1519, fig. (northwestern Pacific); Nakabo, 2002: 185, figs (Honshu, Shikoku and Kyushu, Japan); Yamaguchi, 2002: 29 (Ariake Bay, Japan); Senou et al., 2006: 404 (Sagami Bay, Japan); Matsuura et al., 2009: 15 (Aomori, Iwate, Miyagi and Fukushima, Japan); Abe et al., 2012: 190 ( Japan); Grigorov & Orlov, 2013: 928 (Sea of Okhotsk); Nakabo, 2013: 229, figs ( Japan).

Myliobatis cornuta Günther, 1870: 490 ( Japan) : Ishikawa & Matsuura, 1897: 60 (Matsushima, Japan); Philippi, 1892: 8 ( Japan); Tokida & Kobayashi, 1967: 180 ( Japan).

Myliobatis cornutus Jordan & Snyder, 1901: 43 (Nagasaki, Japan).

Myliobatis tobijaei: Luther, 1909: 152 (Yokohama, Japan).

Aetobatis tobijei : Jordan et al., 1913: 30 (Hakodate to Nagasaki).

Holorhinus hamlyni: Fowler, 1941: 460 ( Japan) .

Holorhinus tobijei: Fowler, 1941: 463 ( Japan, Korea,? China); Okada, 1955: 34, fig. (southern Japan); Okada & Mori, 1958: 35, fig. 33 (Mie Prefecture, Japan); Katayama & Fujioka, 1958: 1149 (Yamaguchi Prefecture, Japan); Dotsu & Tomiyama, 1967: 6 (Nagasaki, Japan); Ueno, 1971: 70 (southern Shakotan Peninsula, western Cape Erimo, coast of Soya and Kitami districts, and near Sendai Bay, Japan); Shiogaki & Dotsu, 1973: 15 (Nomozaki, Japan).

Aetobatus tobijei: Kamohara, 1950: 19 (Tosa and Kishu, Japan); Kuroda, 1951: 317 (Hokkaido, Tokyo Bay, Suruga Bay, Kii Peninsula, Shikoku, Kyushu, Tsushima in Japan; Korea?); Kamohara, 1952: 11 ( Kochi, Mimase, Urado and Susaki, Japan); Mori, 1952: 27 (Fusan[=Busan] and Quelpart[=Jeju] Island, Korea).

Myliobatis tobiyei: Kamohara, 1958: 8 (Hokkaido to southern Japan).

Myriobatis tobijei : Kamohara, 1964: 10 ( Kochi Prefecture, Japan); Yamaguchi, 2004: 44, fig. 3 (Ariake Bay, Japan).

Holotype. RMNH 7461 (largest of 2; holotype of Myliobatis tobijei ), juvenile female 236 mm DW (405 mm TL), Nagasaki, Japan.

Other specimens. (53 specimens): BMNH 1862.11.1.74 (holotype of Myliobatis cornuta ), adult male 429 mm DW, Japan; BMNH 1878.4.54.86, 2 specimens, Japan; BMNH 1879.5.14.423, subadult male, Japan; BMNH 1925.3.13.2, 2 juvenile males 272 mm DW and 276 mm DW, China; BMNH 1937.7.17.18 and 19, 2 embryos, male 159 mm DW, female 158 mm DW, Japan; FNU unregistered, dried jaws only from adult specimen, Ariake Bay, Japan; HUMZ 74436, adult male 619 mm DW (1257 mm TL), Japan; HUMZ 105905, juvenile male 266 mm DW, HUMZ 105906, juvenile male 277 mm DW, off Itado, Shimoda, Shizuoka Prefecture, Japan, 19 Nov. 1985; HUMZ 105937, juvenile male 304 mm DW, Shimoda Bay, Shimoda City, Shizuoka Prefecture, Japan, 18 Nov. 1985; HUMZ 105969, juvenile male 286 mm DW, HUMZ 105983, juvenile male 268 mm DW (480 mm TL), off Tatado, Shimoda City, Shizuoka Prefecture, Japan, 20 Nov. 1985; HUMZ 107419, female 342 mm DW, HUMZ 107420, female 396 mm DW (592 mm TL), HUMZ 107421, female 304 mm DW, HUMZ 107422, juvenile male 323 mm DW (536 mm TL), HUMZ 107423, female 356 mm DW, Shimoda Bay, Shimoda City, Shizuoka Prefecture, Japan, Sep. 1985; HUMZ 107437, female 295 mm DW (493 mm TL), Japan; HUMZ 107438, juvenile male 278 mm DW, HUMZ 107439, adult male 472 mm DW (~ 715 mm TL), Japan; HUMZ 107440, female 324 mm DW, Shimoda Bay, Shimoda City, Shizuoka Prefecture, 24 Nov. 1985; HUMZ 107454, juvenile male 296 mm DW, off Shirahama, Shimoda City, Shizuoka Prefecture, Japan, 1986; HUMZ 107455, juvenile male 254 mm DW (476 mm TL), HUMZ 107456, juvenile male 245 mm DW, off Shirahama, Shimoda City, Shizuoka Prefecture, Japan, 27 Jan. 1986; HUMZ 107457, female 404 mm DW (666 mm TL), off Shirahama, Shimoda City, Shizuoka Prefecture, Japan, 30 Jan. 1986; HUMZ 107458, female 299 mm DW, presumably Japan; HUMZ 109718, adult male 480 mm DW, Japan; HUMZ 109719, juvenile male 323 mm DW, HUMZ 109720, 308 mm DW (548 mm TL), HUMZ 109721, female 348 mm DW, HUMZ 109722, female 296 mm DW, HUMZ 109723, female 317 mm DW, HUMZ 109724, female 214 mm DW, Japan; HUMZ 109725, juvenile male 248 mm DW (469 mm TL), HUMZ 109726, juvenile male 303 mm DW, HUMZ 109727, juvenile male 317 mm DW, HUMZ 109728, subadult male 410 mm DW (742 mm TL), HUMZ 109729, female 312 mm DW, Japan; HUMZ 111032, female 257 mm DW, off Shirahama, Izu Peninsula, Shizuoka Prefecture, Japan, 3 Mar. 1986; HUMZ 114481, female 266 mm DW, presumably Japan; NSMT-P 53341, juvenile female 243.5 mm DW (462 mm TL), Tachibana Bay, Japan, 32°35.64′ N, 129°55.37′ E, 60 m depth, 9 Sep. 1996; NSMT-P 61770, juvenile male 248 mm DW (464 mm TL), Miho Peninsula, Honshu, Japan, 24 Apr. 1978; NSMT-P 65303, female 301 mm DW (534 mm TL), Totoro fishing port, Nobeoka City, Japan; NSMT-P 74603, juvenile female 264 mm DW (478.5 mm TL), Onahama, Iwaki City, Fukushima Prefecture, Honshu, Japan, 1931–1935; NSMT-P 75070, juvenile male 289 mm DW (561 mm TL), off Miyako, Shimohei County, Iwate Prefecture, Honshu, Japan, 6 or 7 Jan. 1938; NSMT-P 92524, female 261 mm DW (510 mm TL), Honshu, Japan; NSMT-P SK 871, juvenile female 287 mm DW (510 mm TL), eastern Honshu, Japan, 15 Oct. 1957; NAG002 (not retained), juvenile female 324 mm DW (605 mm TL), NAG003 (not retained), juvenile female 441 mm DW, NAG004 (not retained), pregnant female 656 mm DW, Nagasaki, Japan, June 2013.

Diagnosis. A small Myliobatis (attaining about 665 mm DW) with the following combination of characters: dorsal surfaces yellowish brown, usually with variable, irregular dark blotches; tail with a very weak ventral skin fold; stinging spine(s) relatively long (longest spine 10.3–18.6% DW); interorbital space shallowly concave in adult males; anterior margins of pectoral fins moderately convex; cranial fontanelle (visible in dorsal view without dissection) relatively narrow with mostly straight lateral margins; claspers of adult males 6.6–10.2% DW; predorsal length 66.6–78.8% DW; teeth in 7 rows in each jaw, with a broad median row flanked by three smaller rows on each side; pectoral-fin radials 79–85 (excluding rostral propterygial radials anterior of eyes); total vertebral centra (including synarcual) 115–124; males mature by 429 mm DW.

Description. Disc diamond-shaped, broad, moderately long, width about 1.70 (1.53–1.71) times disc length; anterior projection 4.09 (3.61–4.32) in disc length; axis of greatest width of disc just posterior to scapular region, over anterior abdominal cavity, its horizontal distance from snout tip 1.48 (1.29–1.56) times in distance from tip of snout to pectoral-fin insertion; moderately deep, greatest thickness above scapular region and posterior head, thickness 8.62 (7.45–9.63) in disc width; without denticles or thorns; a short, bony ridge on midline above scapular region. Pectoral fins very large, wing-like, triangular, not or slightly falcate; anterior margin weakly to moderately convex, moderately convex distally; apex moderately rounded, pectoral angle 64 (58.5–67)°; posterior margin shallowly concave; free rear tip angular; inner margin moderately convex; length of anterior margin 47.7 (46.2– 51.2)% DW, 1.11 (1.05–1.20) times its base length, inner margin 5.06 (5.30–7.97) in its base; origin below and just posterior to margin of eye; apex located at about level with pectoral mid-base; insertion just posterior to pelvic-fin origin, well anterior to dorsal-fin origin; free rear tip partly overlapping pelvic-fin anterior margin.

Head pronounced, relatively low, short and broad; projecting well anterior to pectoral-fin origins; subquadrangular in cross-section at pectoral-fin origin; cranial region of head very broadly rounded to almost truncate in dorsoventral view; snout abruptly convex anterior of eyes, becoming deeply concave at origin of rostral lobe; moderately to slightly convex ventrally; ventral head length 27.3 (26.0–31.2)% DW, 1.58 (1.28–1.70) times width at pectoral-fin origins, 4.18 (3.38–5.30) times preorbital length (horizontal), 2.52 (2.32–3.30) times interorbital width; preoral snout length (1.00–1.41) times mouth width, 1.64 (1.35–1.84) times internarial width, 0.63 (0.55–0.84) times distance between first gill slits; head width at pectoral-fin origin 17.2 (17.7–21.9)% DW, 1.81 (1.63–2.21) times its height. Rostral lobe fleshy, broad, short (slightly longer in adult males); broadly rounded in dorsoventral view with a broadly rounded apex; narrowly rounded in lateral view; dorsal surface with a roughly T-shaped patch of pores medially; its length 5.2 (3.8–7.8)% DW, 5.22 (4.02–7.38) in head length, its width 1.14 (1.14–1.35) in head width at pectoral-fin origin.

Interorbital space broad, shallowly convex (moderately convex in adult males) but with a broad medial depression over the cranial fontanelle, without ridges, denticles or thorns; interorbital width 10.8 (9.1–12.1)% DW, 1.56 (1.49–2.01) times orbit length, 0.66 (0.56–0.67) times head width at mid-eye; margins of cranial fontanelle narrowest posteriorly, gradually widening anteriorly, without a rapid change in degree of widening. Eyes moderately large, oval, lateral on head (eyes not visible in dorsal view), angling very slightly inwards anteriorly, diameter 2.04 (1.63–2.75) in spiracle length, 5.35 (4.98–7.47) in head width at pectoral-fin origin; orbits pronounced (very pronounced in adult males) and visible above upper margin of head; a small bony horn present above anterior quarter of each orbit in adult males. Spiracles moderately large, elliptical to slit-like, situated almost entirely laterally on head (not or only slightly visible in dorsal view), just posterior to orbit and above pectoral-fin origin, length 6.6 (6.1–7.5)% DW, 4.87 (2.80–5.70) times width; upper margins with a fleshy fold which is mostly nearly straight but angled inwards near posterior margin of spiracle.

Nostrils narrowly oval with a narrow, fleshy oronasal groove; anterior nasal fold thin, membranous, internal; posterior nasal fold larger, fleshy, extending about two thirds of nostril width from its lateral margin; internarial space 0.98 (0.77–1.07) in prenasal length, 1.44 (1.30–1.84) times nostril length. Nasal curtain large, broad, elongate, width (1.58–1.98) times length; lateral margin weakly concave with a small lateral protuberance at widest point; posterior margin weakly concave, not divided by a medial notch, bordered by a long, curtain-like fringe which follows contour of lower jaw; apices subangular to moderately rounded; a patch of minute pores present near central posterior margin; apex and posterolateral margin recessible within oronasal groove; a small, low fleshy protuberance present on mid ventrolateral margin.

Mouth moderately large, broad, transverse, located ventrally, width (8.2–10.3)% DW, (0.71–1.00) times preoral length, (1.89–2.30) in head width at pectoral-fin origin; margin of lower jaw slightly concave laterally and moderately convex medially, not indented at symphysis; not strongly protrusible, one series of anterior teeth of lower jaw sometimes visible when mouth closed; skin on chin and at margin of lower jaw fleshy, strongly furrowed, papillate. Teeth in 7 rows in each jaw, coalesced to form plates; middle series of teeth in both jaws broad and hexagonal, flanked by three rows of much smaller, similarly-sized, diamond-shaped teeth on each side arranged in a pavement-like fashion; median tooth row about 5 times width of outer tooth rows; upper tooth plate length slightly wider than long (based on FFNU unregistered, see Fig. 15a ); lower jaw tooth plate length about 1.4 times its width, its width about two thirds mouth width, in 11 series (based on FFNU unregistered, see Fig. 15 b).

Gill openings small, elongated S-shaped, forming a weakly fringed lobe laterally; length of first gill slit 1.15 (1.19–1.73) times length of fifth gill slit, (3.45–5.42) in mouth width; distance between first gill slits 2.62 (2.01– 2.55) times internarial space, 0.59 (0.49–0.64) times ventral head length; distance between fifth gill slits 1.42 (1.03–1.41) times internarial distance, 0.32 (0.25–0.35) times ventral head length.

Pelvic fins relatively large, moderately broad, subquadrangular, anterior margin slightly concave, apex subangular, posterior margin slightly convex with scalloped edge, free rear tip very broadly rounded to subangular, inner margin slightly convex; extending well beyond pectoral-fin free tips; pelvic-fin length 16.9 (14.5–19.6)% DW, 1.23 (0.91–1.23) times width across fin bases, inner margin 6.2 (6.2–9.0)% DW. Claspers of adult males (n=4) moderately long, moderately broad, not tapering distally except near tip, apex bluntly pointed, outer length (6.5– 10.2)% DW.

Dorsal fin small, slightly raked back, almost semicircular, its origin well posterior to pelvic-fin free rear tips by about an eye diameter or more; anterior margin moderately convex; apex broadly rounded, just anterior to or opposite insertion of fin; posterior margin moderately convex; free rear tip subangular, inner margin short, straight; predorsal length 1.42 (1.27–1.50) in disc width, fin length 6.6 (5.5–8.2)% DW, height 0.40 (0.37–0.52) times its length, inner margin 16.93 (4.75–12.73) in fin length.

Tail very long, slender, whip-like, its length (from cloaca origin) 1.18 (0.94–1.48) times disc width; tapering gradually at base to stinging spine, and gradually becoming more whip-like beyond sting; base moderately compressed, suboval in cross section at pelvic-fin insertion, tail width at pelvic insertion 1.29 (1.29–1.85) times height; almost quadrangular in cross section near origin of stinging spine, width 0.97 (1.02–1.44) times height at first spine origin; a very weak, low dorsal skin fold present beyond sting; a distinct, low ventral skin fold present; a lateral skin fold present on either side from about level of mid-pelvic inner margin to below base of first stinging spine; a weak groove on dorsal surface of tail immediately posterior to base of stinging-spine(s), partially housing spines. Stinging spines 1–2, very elongate, slender, moderately broad-based, strongly tapered, mostly serrated laterally except for basal portion; distance from sting base to pectoral-fin insertion 25.7 (20.9–28.7)% DW; longest stinging spine 14.6 (10.3–18.6)% DW, 2.21 (1.59–2.90) times dorsal-fin length.

Vertebral centra total (including synarcual) 115–124 (n=7); total (excluding synarcual) 110–117 (n=7); monospondylous (including synarcual) 36–37 (n=9); monospondylous (excluding synarcual) 29–31 (n=9); predorsal diplospondylous 34–44 (n=9); post-dorsal diplospondylous 41–ca. 47 (n=7). Total pectoral-fin radials (excluding rostral propterygial radials anterior of eyes) 79–85 (n=12); propterygium (posterior of eyes) 20–22 (n=7), mesopterygium 16–21 (n=7), metapterygium 42–45 (n=6). Pelvic-fin radials: 1 (2–3 fused elements) + 17– 18 (n= 5 males); 1 (2 fused elements) + 24 (n= 1 female).

Holotype Other specimens (n=25)

Min. Max. Mean ......continued on the next page Holotype Other specimens (n=25)

Min. Max. Mean Width of fifth gill slit 1.4 1.3 2.1 1.5 Distance from edge of disc to first gill slit 8.3 7.0 8.2 7.6 Distance between first gill slits 16.0 14.9 17.8 16.4 Distance between fifth gill slits 8.7 7.6 9.9 8.7 Tail at axil of pelvic fins (width) 5.4 5.2 6.5 5.9 Tail at axil of pelvic fins (height) 4.2 3.4 4.7 3.9 Tail at origin of stinging spine(s) (width) 1.9 2.0 3.0 2.5 Tail at origin of stinging spine(s) (height) 1.9 1.6 2.5 2.1 Pectoral-fin insertion to spine origin (horiz.) 25.7 20.9 28.7 24.0 Length of first stinging spine 14.6 4.4 18.6 12.6 Length of second stinging spine – 10.3 12.7 11.8 Pectoral-fin insertion to dorsal-fin origin (horiz.) 16.6 14.4 20.7 16.7 Dorsal-fin length 6.6 5.5 8.2 6.7 Dorsal-fin anterior margin 5.7 4.6 6.3 5.3 Dorsal-fin height 2.6 2.3 3.3 2.9 Dorsal-fin posterior margin 2.6 1.9 3.3 2.8 Dorsal-fin inner margin 0.4 0.4 1.4 1.0 Snout to anterior cloaca 53.8 51.0 62.8 54.7 Lower jaw to anterior cloaca 44.2 41.2 51.8 44.6 Cloaca anterior to tail tip 117.8 93.6 147.7 124.8 Cloaca anterior to stinging spine 27.3 20.3 26.5 23.7 Width across pelvic fin bases 13.8 14.1 17.9 16.1 Greatest span of pelvic fins 24.7 16.5 34.2 27.8 Pelvic-fin length 16.9 14.5 19.6 17.1 Pelvic-fin anterior margin 15.0 12.6 16.6 14.5 Pelvic-fin base 12.2 10.4 14.3 11.9 Pelvic-fin posterior margin 10.4 8.8 15.3 12.0 Pelvic-fin inner margin 6.2 6.2 9.0 7.3 Clasper outer length – 5.2 10.2 7.9 Clasper base width – 1.9 3.4 2.9 Colour. When fresh: Dorsal surface yellowish brown; irregular shaped and sized dark brown blotches variably present on dorsal surface of disc; blotches vary from completely absent ( Fig. 9 ), to only several present, to densely covering dorsal surface ( Fig. 11 a, b); dark (dorsal) and pale (ventral) surfaces well demarcated (waterline) along edge of pectoral fins and rostral lobe; paler laterally below eye. Tail dark dorsally; anterior third slightly paler ventrally with a mottled, diffuse waterline on mid-lateral margin; paler ventral coloration often just visible in dorsal view at base of tail; uniformly dark posteriorly. Ventral surface mostly whitish; pectoral fin apices, and anterior and posterior margins darkish brown, with junction between brown areas and whitish ventral colour strongly mottled; distal quarter of pelvic fins brownish; rostral lobe and nasal curtain white.

Size. Males and females examined in this study (excluding embryos which were 158 and 159 mm DW) ranged in size from 245–619 and 214–656 mm DW, respectively. Five males between 429 and 619 mm DW were mature and a 410 mm DW male was adolescent, while 18 males between 245 and 323 mm DW were immature. A female of 656 mm DW was pregnant. Yamaguchi (2004) reported on an abnormal female specimen which was 665 mm DW and weighed 5.5 kg. The largest male examined (619 mm DW) had a total length of 1257 mm.

Distribution. Found in the western North Pacific ( Fig. 8 ). In Russian waters, has been recorded in the Sea of Okhotsk ( Grigorov & Orlov, 2013). Widely distributed throughout mostly southern Japan: in Hokkaido, recorded from off Cape Erimo, the Shakotan Peninsula, Hakodate and Soya and Kitami districts (e.g. Jordan et al., 1913; Ueno, 1971; Amaoka et al., 1989); in the Tohoku region (northern Honshu), recorded off Sendai Bay, Aomori, Iwate, Miyagi, Matsushima, and Fukushima (e.g. Ueno, 1971; Matsuura et al., 2009); in Chubu region (central Honshu), specimens examined take from off Shizuoka and recorded from Suruga Bay (e.g. Kuroda, 1951); in Kanto region (central Honshu), recorded from Sagami Bay, Tokyo Bay and Chiba (e.g. Jordan & Snyder, 1900; Kuroda, 1951; Miya et al., 1995; Senou et al., 2006); in Kinki/Kansai region (southern Honshu), recorded from Mie Prefecture and Kii Peninsula (e.g. Kuroda, 1951; Okada & Mori, 1958); in Chugoku region, recorded off Yamaguchi (e.g. Katayama & Fujioka, 1958); in Shikoku region (southwestern Honshu), recorded off Tsushima, Mimase, Kochi, Susaki and Urado (e.g. Kuroda, 1951; Kamohara, 1952); in Kyushu, recorded from off Nagasaki, Nomozaki and Ariake Bay (e.g. Dotsu & Tomiyama, 1967; Shiogaki & Dotsu, 1973; Yamaguchi, 2004). Records from Ryukyu Islands and Okinawa Trough ( Okamura & Kitajima, 1984; Yano, 1999) probably refer to M. hamlyni but this requires validation to determine if both species may occur in this region. In South Korea, recorded from off Busan and Jeju Island ( Jordan & Metz, 1913; Mori, 1952). In China, recorded from off Ningbo (e.g. Wang, 1933) and Yantai ( Fang & Wang, 1932), but these and other records from off China need to be verified to confirm they are M. tobijei and not M. hamlyni . Occurs mostly in shallow coastal waters to depths of at least 60 m.

Molecular analyses. The molecular data indicate that M. hamlyni and M. tobijei are distinct lineages. Sequences derived from specimens of M. hamlyni and M. tobijei each form separate monophyletic groups that are distinct from each other and from all other Myliobatis species that were included in the analysis. Myliobatis tobijei is sister to M. aquila and these two groups cluster with the group containing sequences that were derived from specimens of M. hamlyni ( Fig. 16 ). We caution however that this inference is based on a single mitochondrial marker. Inclusion of multiple nuclear markers may affect inference of species interrelationships within Myliobatis .

Figures

FIGURE 8. Distribution of Myliobatis hamlyni (black star—holotype; black circle—other records); and M. tobijei (crossed square—holotype; black square—other records) in the East Indian and West Pacific.

FIGURE 9. Dorsal view of the holotype of Myliobatis tobijei (RMNH 7461 [largest of 2], juvenile female 236 mm DW, preserved) from Nagasaki, Japan.

FIGURE 10. Dorsal view of Myliobatis tobijei NAG 004 (pregnant female 656 mm DW, fresh) from Nagasaki, Japan.

FIGURE 11. Dorsal view of two specimens of the spotted form of Myliobatis tobijei: A) HUMZ 109728, subadult male 410 mm DW (preserved); B) HUMZ 107439, adult male 472 mm DW (preserved).

FIGURE 12. Ventral view of Myliobatis tobijei HUMZ 107439 (adult male 472 mm DW, preserved).

FIGURE 13. Ventral view of the head of Myliobatis tobijei HUMZ 107439 (adult male 472 mm DW).

FIGURE 14. Lateral view of head of Myliobatis tobijei HUMZ 107439 (adult male 472 mm DW).

FIGURE 15. A) Upper and B) lower tooth plates of Myliobatis tobijei FFNU unregistered (adult, dried jaws only).

FIGURE 16. Maximum Likelihood tree showing the relationships among Myliobatidae species. The tree was derived from an alignment of mitochondrial NADH 2 sequences (1044 sites) under a GTR + G + I model of molecular evolution.

FIGURE 17. Outline of cranial fontanelle (in dorsal view) of: A) Myliobatis hamlyni and B) Myliobatis tobijei.

Tables

TABLE 2. Proportional dimensions as percentages of disc width for the holotype of Myliobatis tobijei (RMNH 7461 - largest of 2), with ranges and means for 25 other specimens.

Disc width (mm)	236	244	656	358
Total length	171.6	149.5	203.1	179.0
Pre-dorsal length	70.3	66.6	78.8	70.7
Disc, length	58.9	58.5	65.3	60.9
Snout to pectoral-fin insertion	53.2	51.4	58.7	54.4
Disc thickness	11.6	10.4	13.4	12.1
Snout to pectoral-fin origin	14.4	13.8	17.6	15.5
Posterior orbit to pectoral-fin insertion	40.2	39.9	47.0	42.5
Snout to maximum width (horiz.)	36.0	34.5	41.7	38.2
Pectoral-fin anterior margin	47.7	46.2	51.2	48.4
Pectoral-fin posterior margin	49.2	42.5	50.5	46.8
Pectoral-fin base length	43.0	40.5	45.8	43.1
Pectoral-fin inner margin	8.5	5.5	8.2	6.7
Head length (ventral)	27.3	26.0	31.2	28.0
Preorbital length	9.7	9.0	12.3	10.1
Preorbital length (horiz.)	6.5	5.0	8.9	6.5
Head width at pectoral-fin origins	17.2	17.7	21.9	19.5
Head height at pectoral-fin origins	9.5	8.9	12.3	10.4
Head width at mid-eye	16.5	16.0	19.1	17.5
Head height at mid-eye	8.5	8.5	11.2	9.9
Interorbital width	10.8	9.1	12.1	10.7
Interspiracular width	13.6	13.5	15.4	14.5
Spiracle length (longest)	6.6	6.1	7.5	6.9
Spiracle width (narrowest)	1.4	1.1	2.4	1.7
Orbit diameter	7.0	5.2	7.0	6.1
Eye diameter	3.2	2.5	4.3	3.3
Orbit and spiracle length	12.7	11.5	13.4	12.3
Preoral length	10.0	9.1	13.8	10.5
Prenasal length	6.5	6.1	9.5	7.3
Prenasal length (horiz.)	6.0	5.3	8.1	6.1
Rostral lobe width	15.1	14.5	17.8	15.9
Rostral lobe length	5.2	3.8	7.8	4.8
Mouth width	–	8.2	10.3	9.2
Width of upper tooth plate	6.2	4.9	6.0	5.5
Width of lower tooth plate	5.8	4.0	5.5	4.7
Internarial width (external)	6.1	6.2	7.5	6.9
Nasal curtain length	4.2	4.3	5.8	5.0
Nasal curtain width	–	8.4	10.0	9.0
Nostril length (internal)	4.3	3.4	4.9	4.4
Width of first gill slit	1.7	1.7	2.8	2.1
Width of third gill slit	2.1	1.7	2.7	2.2