Platyrhina sinensis ( Bloch and Schneider 1801 )

Iwatsuki, Yukio, Miyamoto, Kei, Nakaya, Kazuhiro & Zhang, Jie, 2011, A review of the genus Platyrhina (Chondrichthys: Platyrhinidae) from the northwestern Pacific, with descriptions of two new species, Zootaxa 2738, pp. 26-40 : 27-30

Platyrhina sinensis ( Bloch and Schneider 1801)

New English name: Amoy Fanray

Figs. 1 A–C, 4, 5; Table 1

Rhina sinensis Bloch and Schneider, 1801: 352 (type locality: China; drawing of Lacepède, 1801: 157, fig. 2, no type known, see Fig. 1 A).

Platyrhina sinensis Müller and Henle, 1841: 125 (type locality: Japan and China, latter locality erroneous, correctly Vietnam [R. Causse, personal communication]; in part [MNHN 0000-1307; 1 of 3 specimens]; see Remarks; redescription). Séret and McEachran, 1986: 37 (Tourane [current Da Nang], Vietnam).

Platyrhina limboonkengi Tang, 1933: 561 , pl. 42, figs. 1–2 (type locality: Amoy, China); Fowler, 1941: 330 ( China); Chu, 1960: 136, fig. 125, 129 ( China); Chu and Wu, 1984: 64, fig. 36 (South China Sea, Taiwan Strait and southern East China Sea); Compagno, 1999: 486 ( China and Vietnam); Carvalho, 2004: 77, fig. 9C (South and East China Sea, western Pacific Ocean). New Synonymy.

Neotype. ASIZB 47094, 204 mm TL, male, off Guangdong, China, 5 Jan. 1965.

Other specimens (206−505 mm TL, n =6). ASIZB 31954, female, 505 mm TL, off Guangdong, China, Nov. 1954; ASIZB 48972, male, 430 mm TL, off Guangdong, China, 2 Feb. 1956; ASIZB 50280, female, 206 mm TL, off Foochow, China, Oct. 1956; ASIZB 182251 (only used for photographs), male, 350 mm TL, off Amoy, China, coll. J. Zhang, 26 july 2009; ASIZB 182256 (only used for photographs), female, 455 mm TL, off Amoy, China, coll. J. Zhang, 26 july 2009; MNHN 0000-1307 (1 of 3 specimens), male, 421 mm TL, Vietnam, coll. Eydoux and Souleyet.

Data from Tang (1933), used in Fig. 4 and Table 1, were taken from the following: ZMUA 280 (holotype of Platyrhina limboonkengi ), male, 447 mm TL, Amoy, China; ZMUA 281 (3 paratypes of P. limboonkengi ), males, 406–456 mm TL, Amoy, China, 6 Aug. 1933; ZMUA 281 (paratype of P. limboonkengi ), female, 517 mm TL, Amoy, China, 6 Aug. 1933.

The following provided extra distributional data: Do Son Marine Museum of Vietnam Academy for Science and Technology, Institute of Marine Environment and Resources 16019-104, female, male and unknown sex (damaged), 3 specimens, ca. 250–500 mm TL, Ky xuan, Ha Tinh Province, north of Danan, Vietnam, 16 Mar. 1976.

Diagnosis. Distinguished from congeners in having the following combination of characters: two rows of thorns (strongly hooked and gradually becoming somewhat embedded toward first dorsal fin origin) on mid-dorsum of tail; thorns absent from anterior part of scapular region ( Fig. 1 B); thorns on the orbital, nape and scapular regions not encircled by light yellow or white pigment ( Fig. 1 B); dorsal surface covered with minute dermal denticles of uniform size and shape, no obvious larger dermal denticles (smooth to touch).

Description. Counts and proportional measurements of the neotype, four non-type specimens of Platyrhina sinensis and five type specimens of P. limboonkengi ( Tang 1933) are shown in Table 1. Data for the neotype are presented first, followed by those of other specimens in parentheses.

Disk broadly wedge-shaped, snout tip slightly angular, outer margins broadly rounded, free rear tip reaching or slightly beyond level of cloaca; preorbital and preoral snout lengths 15% (15–16%) of TL and 17% (15–19%) of TL, respectively (Fig. 4); pelvic fins rounded (free rear tips angled), originating from abdominal surface at end of pectoral fins; tail shark-like, length greater than disc length, 57% (52–60%) of TL, abruptly narrower than disc width, lacking a caudal spine, abdominal surface flat with shallow groove along mid-abdominal axis; one row of thorns on mid-dorsum of nape to tail origin; two rows of thorns on mid-dorsum of tail origin to second dorsal fin origin; dermal-lateral folds on tail, originating well anterior to free rear tip of pelvic fin, reaching just behind caudal fin origin; two widely separated dorsal fins on tail, similar in size and shape, moderately large, anterior margins slightly convex with convex hind margin; first dorsal fin originating 1.3 (1.2–1.4) times maximum disc width from snout tip, well behind free rear tips of pelvic fins but anterior to mid-length of tail; second dorsal fin originating 1.5 (1.3–1.5) times maximum disc width from snout tip; interdorsal space equal to (1.0–1.2 times) first dorsal fin base length, 6 (5–7) thorns on mid-dorsum; caudal fin relatively small, flat, oval, sometimes forming small lobe posterodorsally, dorsal margin length 1.1 (1.1–1.2) times abdominal margin length; head moderately elongate; snout moderately long, soft, flexible; eyes moderately large, not elevated or protruding; spiracles broadly leaf-shaped, 0.7 (0.8–1.0) times eye length, originating beside eyes; nostrils moderately large, nasal flap skirt-shaped; anterior aperture circular, lower part surrounded by short folds; mouth width moderate, upper and lower jaws arched, skin grooves around mouth; oral teeth small, rhomboid, slightly pointed in males, over 56 (58–80) regular rows on lower jaw (increasing with growth), upper and lower jaw teeth similar in shape and size; five pairs of gill openings, two anteriormost widely separated, distance between second to fifth gradually becoming narrower posteriorly; 4 (4–5) thorns (strongly hooked) around on orbits; two pairs of two (total eight, Fig. 1 B) symmetrical thorns on scapular region; thorns absent anteriorly on scapular region ( Fig. 1 B); thorns on orbital, nape and scapular regions not encircled by light yellow or white pigment ( Fig. 1 B); claspers of mature males greatly elongated; entire body and fins covered with minute dermal denticles of uniform size and shape, no obvious larger dermal denticles on dorsal surface (smooth to touch); irregular small thorns aggregated on anterodorsal margin of disk from snout tip to maximum disc width.

Color of fresh specimens. Based on 2 non-type specimens ( ASIZB 182251 and 182256) photographed by J. Zhang: dorsal surface often dark brown, darker medially; dorsal and caudal fins brown; hooked thorns on dorsal surface whitish; abdominal surface whitish, posterior margins of pectoral and ventral fins broadly grayish-brown.

Color of preserved specimens. Based on neotype ( ASIZB 47094) and 4 non-type specimens ( ASIZB 31954, 48972 and 50280; MNHN 0000-1307) photographed by J. Zhang and Y. Iwatsuki, respectively: dorsal surface often dark brown, darker medially; abdominal surface light brown.

Distribution. Platyrhina sinensis is currently known from Amoy, from the Chinese coast of Taiwan Strait and in the South China Sea to northern Vietnamese waters (north of Danan, personal research). It has not been confirmed from Japanese, South Korean or Taiwanese waters, although it likely inhabits the last-mentioned ( Fig. 5 ).

Ecological note. The species has been captured in shallow coastal waters. However, nothing further is known of its ecology.

Remarks. Rhina sinensis Bloch and Schneider 1801 was based on a drawing by Lacepède (1801: 26, pl. 2, fig. 2, vernacular name “RAIE Chinoise”; see Fig. 1 A). Thus, there are no type specimens. The drawing appears to show two clear rows of thorns on the mid-dorsum of the tail ( Fig. 1 A, indicated by red arrows), a feature found in Platyrhina limboonkengi Tang 1933 , although the correct thorn pattern on the dorsal surface of the nape and scapular region is poorly represented, being illustrated as scattered thorns ( Fig. 1 A).

Subsequently, Müller and Henle (1841) redescribed Bloch and Schneider’s (1801) species as Platyrhina sinensis , utilizing three additional specimens: MNHN 0000-1307, male, 421 mm TL, Vietnam, collected by Eydoux and Souleyet and RMNH D (dried) 2696–2697 (females), 445–585 mm TL, Japan, collected by D. W. Bürger. However, RMNH D. 2696–2697 clearly have one row of thorns on the mid-dorsum of the tail, compared with two in MNHN 0000-1307. Because Plate 44 in Müller and Henle (1841) shows one row of such thorns, many subsequent researchers, including Richardson (1846), Temminck and Schlegel (1850), Bleeker (1853), Jordan and Hubbs (1925), Tang (1933), Fowler (1930), Matsubara (1955), Chu (1960), Compagno and Last (1999), Zhu and Meng (2001) and Hatooka (2002), have considered that character as diagnostic for P. s i n e n s i s. It is our contention that the specimens so (erroneously) diagnosed in fact represented an undescribed species of Platyrhina (described herein as P. tangi sp. nov.).

The original description of P. limboonkengi ( Tang 1933) was based on five type specimens (holotype and four paratypes, 406–517 mm TL; see Table 1) at ZMUA, all apparently now lost. Nevertheless, there being no features that sufficiently differentiate P. limboonkengi from P. sinensis , the former is here considered a junior synonym of the latter. ASIZB 47094 (204 mm TL) is here designated as the neotype of Rhina sinensis Bloch and Schneider 1801 in order to avoid further confusion caused by the absence of type specimens.

The combination Discoides sinensis , introduced by Temminck and Schlegel (1850), has no taxonomic value and has been adequately covered by Eschmeyer (1998, 2010 on-line version).

Figures

FIGURE 1. Drawing (A) by Lacepède (1801), the basis of Rhina sinensis Bloch and Schneider, 1801 and neotype (B – C) of Platyrhina sinensis. B) Dorsal view of ASIZB 47092, male, neotype, 204 mm TL, off Guangdong, China; C) Abdominal view of same specimen. Red arrows show 2 rows of hooked thorns on the mid-dorsum of the tail.

FIGURE 5. Distribution of Platyrhina sinensis, P. hyugaensis sp. nov. and P. t a n g i sp. nov. Black dots based on specimens examined during this study; white dots based on literature records (as P. s i n e n s i s).