FIRST RECORD OF THE CHINESE FANRAY , PLATYRHINA SINENSIS ( ELASMOBRANCHII : MYLIOBATIFORMES : PLATYRHINIDAE ) , IN THE SEAWATERS OF ZHUJIAJIAN , ZHOUSHAN , CHINA

There are several studies of the ichthyofauna of the East China Sea, however, the knowledge of fishes from this region still remains incomplete. This report confirms the occurrence of Chinese fanray, Platyrhina sinensis (Bloch et Schneider, 1801), in the seawaters of Zhoushan by analysing nine specimens of the Chinese fanray obtained in Zhujiajian from May 2017 to December 2017. The morphometric measurements and meristic counts were taken. The principal characters that are conclusive for the species were consistent with P. sinensis and were sufficient for separation of the examined specimens from other Platyrhina species. In addition, the fragment of 12S rRNA was also sequenced for the purpose of classification. The mean genetic distance within P. sinensis group was 0.71%, group mean distance between P. sinensis and other Platyrhina species ranged from 6.01% to 7.71%. Species were also separated from each other at the genetic level. Given the Chinese fanray has not been reported to exist in this region, our findings represent the first record from Zhoushan and extend the distribution range of this species into the north of the East China Sea. The reason behind the observed northward migration of some P. sinensis individuals from their southern habitat might be global warming. Collection of many additional specimens is needed to better define the geographic limits of the Chinese fanray.


INTRODUCTION
The marine fish fauna of the East China Sea is characterized by considerable species richness and diversity (Zhao et al. 2012(Zhao et al. , 2016)), and have a significant place in Chinese ichthyology due to the presence of numerous endemic species with restricted distribution ranges.The fish fauna checklist of Zhu and Meng (2001) on the East China Sea includes 647 species, but now the marine fish species of the area lists contains as many as 732 species (Zhao et al. 2016).The increased number of species is a consequence of several factors, such as the introduction of exotic species, range extension of the species, and identification of new species (Zhao et al. 2012(Zhao et al. , 2016)).
It is difficult, however, to make new findings for rare and economically insignificant species such as rays, which have always been overlooked.The Chinese fanray, Platyrhina sinensis (Bloch et Schneider, 1801), is a benthic ray (Bloch and Schneider 1801) occurring from the south of China to Vietnam (Zhang et al. 1955, Chu 1960, Chen et al. 1997, Chu and Wu 1984, Iwatsuki et al. 2011).The knowledge of the distribution of Chinese fanray is still insufficient to define their potential distributional range.In particular, data on their distribution in the East China Sea are still lacking, even though this sea is closest to the south of China.Apart from the Taiwan Strait and the South China Sea, specimens of "P.sinensis" has been recorded in other areas including the East China Sea, however, these records in China were the misidentification of Platyrhina tangi Iwatsuki, Zhang et Nakaya, 2011as P. sinensis (see Tang 1933, Compagno et al. 1999, 2005, Nakabo 2002, Iwatsuki et al. 2011, Zhao et al. 2012, 2016).

MATERIAL AND METHODS
From May 2017 to December 2017, nine samples of Platyrhina sinensis were collected in the seawaters of Zhujiajian (122°25.109′E,29°52.551′N),Zhoushan.Therefore, this paper is the first reliable report from this area and extends the distribution range of the Chinese fanray into the north of the East China Sea.
In order to better preserve the original morphology of the presently reported P. sinensis samples, we kept specimens in a freezer prior to examination.The body colour and pigmentation of specimens were pictured, together with all counts and measurements handled.All collected specimens were identified based on morphological characteristics used by Tang (1933), Last et al. (2006), Iwatsuki et al. (2011), andWhite andLast (2016).The majority of the measurements followed the existing convention for rays and sharks and were taken directly (point to point) unless otherwise stated.Detailed guidance of counts and measurements was listed as follows: total length (TL); snout length (defined as direct length from the snout tip to the firm nasal capsule adjacent the orbit-forward of eye socket); spiracle length (greatest length of the main cavity); pre-oral length (direct length from the snout to the posterior edge of upper jaw at its symphysis); mouth width (taken across the exposed width); pelvic fin insertion to dorsal fin origin-horizontal distance from the pelvic insertion to the origin of the first dorsal fin.

RESULTS
The general morphological features of Platyrhina sinensis are shown in Fig. 1 and Table 1.The most significant character distinguishing this species from others was there were two rows of hooked thorns on middorsum of tail (vs.only one row of hooked thorns on middorsum of tail in P. tangi and P. hyugaensis) (Iwatsuki et al. 2011).Thorns on orbital, nape and scapular regions were not encircled by light yellow or white pigment, which was also different in P. tangi.The detailed counts and measurements of P. sinensis were listed in Table 1, which verified the identification of this species in the north of East China Sea.
The neighbor-joining phylogenetic tree is shown in Fig. 2. Specimens of P. sinensis in the presently reported study clustered in a group, and those of P. tangi and P. hyugaensis clustered in another two groups, respectively.Groups of all species including A. cuspidata were well defined based on the distance of the 12S rRNA sequence.The genetic distance of the 12S rRNA sequence within P. sinensis group was only 0.71%, and the mean distance between P. sinensis and other two Platyrhina species (P.tangi and P. hyugaensis) was up to 6.01% and 7.71%, respectively.The interspecific distance was about 8.5-10.6 times larger than intraspecific distance.Together, both the morphological and genetic analysis strongly supported the validity of P. sinensis as a new record in Zhoushan.

DISCUSSION
Although Platyrhina sinensis has little economic value, it shows significance from the aspect of ichthyofaunal conservation and overall fish diversity.The globe is heating up now with warmer lands and oceans than when record keeping began in 1880, and temperatures are still ticking upward (Brander et al. 2003).In response to climate change, long-term trends and variations in abundances and distribution of many marine fish have been observed over the past few years, such as cod, flatfish, salmonids, and so on (Drinkwater 2005, Farrell 2009, Hermant et al. 2010).The previous report showed that P. sinensis mainly existed in the Taiwan Strait and the South China Sea (Iwatsuki et al. 2011) and no P. sinensis has ever been collected from other sea areas in China (Iwatsuki et al. 2011).In this study, nine P. sinensis individuals were collected from Zhoushan.This paper extends the distribution range of this species into the north of East China Sea and represents the northernmost record of P. sinensis in China.Our findings indicate that global warming might prompt some P. sinensis individuals to migrate northward from its southern habitat like other fishes mentioned above.Attention should be paid to the new region fish species including P. sinensis expanded to because their appearance might indicate climatic change, which may make a big difference for local fishery production and fish diversity.

ACKNOWLEDGEMENTS
Mr Minguang He contributed much to the specimen collection.This work was supported by the National Natural Science Foundation of China ( 41776171