中国伊洛瓦底江和怒江褶鮡属鱼类的形态差异及分类地位

Morphologic Differentiation and Taxonomic Status of Pseudecheneis (Siluriformes: Sisoridae) from Irrawaddy and Salween Drainages, China

将采自中国伊洛瓦底江和怒江中115尾褶鮡属(Pseudecheneis)鱼类标本以采集地分为10组,对它们开展多变量形态度量学研究,共测量了25个框架性状和14个常规性状。经两次主成分分析,逐步提取分值散点聚在一起的标本,最终分离出5种不同的类型。第1类仅分布于伊洛瓦底江支流龙川江中下游,以其尾柄细长,区别于其他类型,确认为细尾褶鮡(P.stenura),其余4类均是未被描记的新种。第2类分布于伊洛瓦底江支流龙川江上游,体型极度纤细延长。第3类分布于怒江支流湾甸河,以胸鳍长为主要鉴别特征区别于其他类型,综合解剖学和分子生物学的系统发育研究结果,这类标本应是未被描记的一新种。第4类和第5类分别分布于怒江支流南汀河及伊洛瓦底江支流大盈江,它们以背部色斑的差异相互区分。此外,腾冲曲石部分标本的度量数据无法与大盈江的标本区分,外部形态特征亦无差异。它们是同一种类的不同地理种群,还是不同的种类,或者腾冲曲石的这些标本是另一新种?这些猜测均有待后续采用其他方法研究后进一步确认。

One hundred and fifteen specimens of Pseudecheneis from the Irrawaddy and Salween drainages were divided into ten groups according to localities. When analyzed by the methods of multivariate morphometrics, twenty-five frame and 14 general characteristics were measured. According to the results of principal components analyzed twice, specimens clustered together by scatter plots of scores were gradually picked up and could be divided into five types. The first type only occurred in the middle and lower Longchuan Jiang, a branch of Irrawaddy. It is distinguished from other types by its slender and elongated caudal peduncle and can be identified as P stenura. The other four types were un-described species. The second type was distributed in the upper Longchuan Jiang, a branch of the Irrawaddy and they had an extremely elongated body. The third type appears in the Wandian He, a branch of the Salween. And the length of its pectoral fin was longer than others which was the main distinguishing characteristic from the other types. Combined with the anatomical and phylogenic results and molecular biological studies, this type is considered an un-described species. The fourth and fifth types occur respectively in the Nanding He, a branch of the Salween and the Daying Jiang, a branch of the Irrawaddy. They differ from each other by the color pattern on the dorsal surface. Furthermore, some specimens from Qushi of Tengchong County and specimens from the Daying Jiang are not differentiated by morphometrics or external characteristics. They belong to a different geographic population of the same species. Different species, or specimens from Qushi of Tengchong County can be considered a new species. All suppositions should be confirmed by further studies in the future.