中国鲟科一新记录种——小体鲟

First Record of Sterlet Acipenser ruthenus(Acipenseriformes:Acipenseridae)in China

在中国,小体鲟(Acipenser ruthenus)被认为自然分布于额尔齐斯河,但至今尚无发现该种的文献报道,在额尔齐斯河是否确有分布还存疑问。2019年9月,在中国额尔斯斯河下游(185团)采集到鲟类标本1尾,全长91.5 cm,体重5520 g。标本背骨板11,侧骨板64,腹骨板12;口腹位,较小,口下唇中间断裂;鳃耙数17,符合小体鲟的形态特征。利用线粒体DNA Cyt b基因序列(1141 bp),对鲟属10个物种的亲缘关系及系统发育进行分析,该种与分布于鄂毕河、多瑙河的小体鲟遗传距离最近(序列分歧为0~0.0002),并在进化树中聚为一支,应属于种内关系。基于以上研究结果,可以确定该标本即为小体鲟,在额尔齐斯河首次被发现,为中国鲟科分布新记录种,标本保存于中国水产科学研究院黑龙江水产研究所鱼类标本馆(标本号80092871)。

In China,Acipenser ruthenus is considered to be naturally distributed in the Irtysh River,but there is no report on them,and whether it is distributed in the Irtysh River.We collected a sturgeon specimen in the lower reach of the Irtysh River(185 Corps)in northwest of China in September,2019(Fig.1).The Body length of the specimen is 91.5 cm,the weight is 5520 g;11 dorsal scutes,64 lateral scutes and 12 ventral scutes.Mouth ventrally situated and small,middle of the lower lip clearly slit and 17 gill rakers,which conforms to the morphological characteristics of A.ruthenus(Fig.2).According to the phylogenetic and genetic distance analysis of 10 species of the genus Acipenser based on the mitochondrial Cyt b gene sequence(1141 bp,Table 1),the results showed that the genetic distance of this specimen is the closest with A.ruthenus in Danube and Ob River(sequence divergence was 0-0.002),and they have gathered on one branch of the evolutionary tree,which should be intraspecific(Fig.3).In summary,determined that this specimen is A.ruthenus,and the species was the first time discovered in the Irtysh River,and also a new record species of Acipenseriformes distributed in China.The specimen was preserved in the herbarium of fisheries in the Heilongjiang River Fisheries Research Institute,Chinese Academy of Fishery Sciences(Specimen No.80092871).