中国沿海鯻科鱼类DNA条形码研究及新记录种三线鯻分类地位探讨

鯻科鱼类是广泛分布于印度-西太平洋常见经济鱼类,由于不同物种间外部形态较为相似,且种内有一定变化,物种鉴定存在一定困难。为明确中国鯻科鱼类的分类地位,对中国鯻科鱼类进行了详细的形态计测,并测定了3属共62 ind鱼类COI基因5’端652 bp COI序列,结合Gen Bank中三线鯻3个地点9条序列,发现我国除已报道的3属4种鯻科外,新发现目前仅见于广东的三线鯻,是中国鯻科鱼类的新纪录。在基于Kimura-2-paramter的邻接树上,5种鯻科鱼类均独立成支。种间遗传距离18.34%(15.9%~20.1%)约为种内遗传距离0.72%(0.1%~2.7%)的24.93倍,形成较为明显的条码间隙。三线鯻可按地理来源分为西太平洋和印度洋-地中海2个谱系,具有明显的谱系结构和地理结构;谱系间遗传距离为5%(0.2%~5.6%)为谱系内遗传距离0.85%谱系A为0.6%(0~1.7%),谱系B为1.1%(0.2%~5.6%)]的5.88倍,谱系间与谱系内遗传距离倍数略低于大多数物种(种间是种内遗传距离10倍),但远高于其种内遗传距离一般小于2%的范围。同时,鯻科内种间在形态上存在诸如侧面体型细长扁平或肥厚、臀鳍是否带隐约散点斑纹、背鳍硬棘的Ⅲ–VI或Ⅶ-Ⅷ间是否有黑色斑点、头部至背鳍前端略带蓝灰或黄绿光泽、身体背部浅灰或浅棕色等区别。分子和形态差异表明,印度-西太平洋分布的三线鯻可能是2个亚种乃至2个种。由于本文分析的三线鯻的数量和地理范围有限,其准确的分类地位仍需要更多的形态计测和核基因数据等研究加以确定。

DNA barcoding of Terapontidae and taxonomic status of a new record of Terapon puta in costal waters of China

Terapontidae is a common economic fish,widely distributed in Indo-western Pacific.Due to the low interspecific variability and a degree of intraspecific differences,the accurate identification of Terapontidae is hardly achieved only by the external morphological charaters.To clarify the classification of Terapontid found in the coastal waters of China,all the putative species were subjected to the morphometric and molecular analysis.The 5'end of COI sequence (652 bp)from 62 terapontid individuals were sequenced,combined with 9 Terapon puta sequences from 3 sites in Indian Ocean and Mediterranean Sea downloaded from GenBank and BOLD as references.The results suggested that T.puta was a new record in China,and the specimen was kept in the department of Ecology,Jinan University.The interspecific genetic distances 18.34％ (15.9％-20.1％]) were 23.93 times greater than the intraspecific distances 0.72％ (0.1％-2.7％)],indicating a clear barcoding gap between them.5 terapontid species each could be independently divided into 5 monophyletic clades based on Kimura-2-parameters in the phylogenetic tree.Of which T.puta could be further divided into 2 independent geographically-defined lineages:Western Pacific,and IndianMediterranean.As interlineage genetic distances 5％ (0.2％-5.6％)] are 4.88 times greater than the intralineage distances {0.85％ lineage A was 0.6％ (0-1.7％)],lineage B was 1.1％ (0.2％-5.6％) } in T.puta,which was slightly lower than the interspecific/intraspecific ratios,but a much higher than the intraspecific genetic distances (2％) for most species.Moreover,there are some visible morphological differences between the lineages of T.puta such as:body elongate and flat or thickening lateral,anal fin with faint scattered spots or not,dorsal fin with the black spots located between the third to the sixth or seventh to eighth spines or not,upper head to the front part of dorsal fin with or without bluish grey or yellowish-green lustre and the backside of body colored with light gray or brown.Overall,summaries of morphological measurements and molecular analyses suggested that the 2 lineages of T.putamight belong to 2 subspecies or even 2 species.However,the insufficient sampling size,limited sampling area and the only maternal genetic data bring incomplete information in this study.So the species status identification work demands the further morphological and nuclear genetic studies based on more individual samplers from wider range of species.