中文摘要：

以文蛤如东群体（RD）和北海群体（BH）为对照群,利用线粒体COⅠ基因序列分析技术对苍南文蛤（CN）和北海白壳文蛤（BW）进行了分子鉴定。结果表明,苍南文蛤和斧文蛤的碱基组成非常相似,通过文蛤属贝类基因序列同源性比对和分子系统聚类分析发现,苍南文蛤CN1、CN2与斧文蛤的同源性分别达到100.0%、99.2%,在依据遗传距离构建的系统进化树上,2个苍南文蛤也与斧文蛤单独聚为一支,据此将苍南文蛤确定为斧文蛤,此结果将斧文蛤的分布区域向北扩展到了浙江南部沿海,修正了现有文献中记载的仅在我国南海诸省分布的说法;而白壳文蛤与其它6种文蛤的基因序列同源性都不高（79.6%～85.3%）,在系统进化树上单独分出一支,明显是独立于这些文蛤之外的新种。斧文蛤、白壳文蛤与文蛤群体COⅠ基因的遗传多样性分析显示,文蛤BH群体的变异位点数、单倍型数和核苷酸多样性指数均最大,斧文蛤其次,而白壳文蛤10条基因序列完全相同,未发生任何核苷酸位点变异,说明其遗传多样性很低。应用方差分析和Tukey多重比较,分析了斧文蛤、白壳文蛤与文蛤群体的形态差异,发现斧文蛤的壳长明显大于壳高,且SMW/TW、IW/TW 2个参数与文蛤、白壳文蛤群体差异显著（P〈0.05）;而白壳文蛤的壳宽指数大、壳型相对膨胀,SW/SL和SW/SH值均最大,与文蛤和斧文蛤群体差异显著（P〈0.05）。本研究结果可为文蛤属贝类种间鉴别、种质资源保护及系统进化研究提供基础资料。

英文摘要：

Although many species of the genus Meretrix are commercially-important cultured bivalves,the taxonomy of Meretrix is still in argument over several discrepancies among scientists in the world.Compared with the groups of Meretrix meretrix（RD BH）,two groups of Meretrix clam（CN BW）,collected from Cangnan and Beihai,were phylogenetically analyzed and molecularly classified based on partial sequences of the mitochondrial COⅠ gene.The results indicated that the base sequence of CN group and M.lamarckii with similar composition was the highest in homology of 100.0% and 99.2%,respectively.Phylogenetic NJ and UPGMA tree of Meretrix based on genetic distance also showed that CN1 and CN2 were clustered together with M.lamarckii firstly.Therefore we classified CN group as M.lamarckii,which extended the geographic distribution of M.lamarckii from Taiwan to the southern coast of Zhejiang and corrected the existing document claims.But,the BW group shared low sequence homology（79.6%-85.3%）with other six species of Meretrix and formed much independently cluster beyond among groups.Number of polymorphic sites,indexes of haplotype diversity and nucleotide diversity revealed that the level of genetic diversity from high to low was BHM.lamarckiiRDBW.The COⅠ gene sequences of BW group showed very low genetic diversity and no nucleotide variation among 10 individuals.The morphological characters of M.lamarckii,BW and M.meretrix were analyzed using statistical analysis of AMOVA and Tukey＇s multiple comparisons for seven morphological traits.Three morphological parameters,including SH/SL,SMW/TW and IW/TW,of M.lamarckii differed significantly with M.meretrix and BW（P0.05）.BW with relatively expanded shell shape differed significantly with M.meretrix and M.lamarckii in parameters of SW/SL and SW/SH（P0.05）.These results can be expected to provide basic data for the studies of species identification,germplasm conservation and phylogeny.