中国大陆近海新记录种——长冠羊舌鲆(Arnoglossus macrolophus)

A New Record Species Along the Coastal Waters of the Chinese Mainland—Arnoglossus macrolophus

历史记录我国大陆羊舌鲆属(Arnoglossus)有5个物种,它们是长鳍羊舌鲆(A.tapeinosoma)、纤羊舌鲆(A.tenuis)、多斑羊舌鲆(A.polyspilus)、大羊舌鲆(A.scapha)和日本羊舌鲆(A.japonicus)。1929年Weber等将长冠羊舌鲆(Arnoglossus macrolophus Alcock,1889)列为长鳍羊舌鲆[Platophrys(Arnoglossus)tapeinosoma Bleeker,1866;目前为A.tapeinosomus]的同物异名,并被国内外许多学者所采纳。Arai等1996年重新检视了长鳍羊舌鲆的模式标本和Weber等的长鳍羊舌鲆,发现了Weber等的标本应为长冠羊舌鲆,确认了长冠羊舌鲆种的有效性。作者2008至2021年间在中国大陆近海采集到了一批拟似长鳍羊舌鲆和长冠羊舌鲆的标本,为了正确鉴定这些标本,本研究对其形态和分子条形码进行了研究,将我们所采集标本的形态特征与两种模式种以及前人的研究数据进行了比较。结果表明,本研究标本的8个可数性状和20个性状比例值与长冠羊舌鲆的数值为相同、连续、包含或略有差异关系;特别是在作为鉴别特征的背鳍条延长、背鳍和臀鳍末端基部黑色斑点和犁骨发达这3个描述性状上为一致,但与长鳍羊舌鲆的特征存在较多差异,因此,本研究的标本确定为长冠羊舌鲆。计算本研究获得的COI序列(Gen Bank登录号:MZ086865)与Gen Bank上的1条采集地为中国台湾的长冠羊舌鲆的遗传距离为12%,与其他3条分别采自中国南海和越南的长鳍羊舌鲆序列的遗传距离为0。因此,这些采自中国南海和越南的标本应该是长冠羊舌鲆而不是长鳍羊舌鲆,因为没有采自中国台湾的长冠羊舌鲆标本的形态信息,无法判断其正确的种。本研究所采集长冠羊舌鲆为首次在中国大陆近海海域发现,故为新记录种。基于所采集标本的形态数据并整合模式种及前人研究的结果,本研究对该种类进行了再描述。主要鉴别特征为,雄鱼前1~6根背鳍条延长成丝状,侧线的弧形和直线的接合处有一个较大的深褐色斑,侧线的后部直线部分有两个小黑斑,有眼侧近胸鳍末端有一黑斑,背鳍和臀鳍末端基部分别有一个稍大的黑色斑点,体背缘和腹缘分别散布一行约5或6个和3或4个淡黑色斑点。

[Objectives]According to Li’s“Fauna Sinica,Osteichthyes,Pleuronectiformes”in 1995,the five species with specimen of genus Arnoglossus in Bothidae were records along the coastal waters of the Chinese mainland,including the Arnoglossus tapeinosoma,A.tenuis,A.polyspilus,A.Scapha and A.japonicus.Weber et al.listed Arnoglossus macrolophus Alcock,1889 as synonym of Platophrys(Arnoglossus)tapeinosoma Bleeker,1866(currently Arnoglossus tapeinosomus)in 1929,this opinion has been accepted by many authors at home and abroad.In 1996,Arai et al.re-examined the holotype of A.tapeinosoma,and checked the specimens of A.tapeinosoma supposedly conspecific by Weber et al.and other researchers.They pointed out that all these specimens misidentificated as A.tapeinosomus should be A.macrolophus;A.macrolophus was affirmed to be the valid name.During this study from 2008 to 2021,off the coast of China's Mainland,samples resembling A.macrolophus and A.tapeinosomus were found,in order to correctly identify the specimens,the morphology and molecular barcodes were studied in this study.[Methods]The morphological features of representative samples were compared with that of type specimen and related research data of A.tapeinosoma and A.macrolophus.[Results]The results showed that the eight meristic features and 20 proportional values in our samples were the same,continuous,inclusive or slightly differece with those of A.macrolophus(Table 1).In particular,all three distinguishing features of elongated dorsal fin rays,black spots on the end of dorsal and anal fins,and developed prevomer are consistent,but there are many differences with the characteristics of A.tapeinosomus.Thus,the samples in this study were identified as A.macrolophus.The genetic distance of the COI sequence obtained in this study(GenBank number:MZ086865)was 12%between one of A.macrolophus collected from Taiwan,China,and zero between three others of A.tapeinosomus collected from the South China Sea and Vietnam downloaded on GenBank.Therefore,these three samples from the South China Sea and Vietnam were misidentified as A.tapeinosomus and should be A.macrolophus,but the species of A.macrolophus from Taiwan,China cannot be determined without specific morphological information of specimen.[Conclusion]This species of A.macrolophus was found for the first time along the coastal waters of Chinese mainland,thus a new record species.Accordingly,A.macrolophus is redescribed herein based on the morphological data of type specimen,the results of ours and previous studies.The main diagnostic characters of this species are:the first 1-6 dorsal fin rays of the male prolonged into long filaments,a large dark brown spot at the junction of the straight and curved lateral line,a large dark spot on distal part of pectoral,two small black spots on the straight of the lateral line,a slightly larger black spot on the of the posterior dorsal and anal fin bases,and a row of about 5-6 and 3-4 pale black spots scattered near the margins of dorsal and ventral fins,respectively.