厚蟹属种群形态量度分析

对天津厚蟹6个种群和侧足厚蟹4个种群的33项形态比例参数进行了多元分析和差异系数(CD)计算。聚类分析没有把天津厚蟹和侧足厚蟹作为2个种分开,而是除侧足厚蟹泉州种群外的9个种群聚类到一起,10个种群之间的欧氏遗传距离也表明它们之间有着较近的亲缘关系。判别分析结果显示,除侧足厚蟹泉州种群(88.9%)和天津厚蟹塘沽种群(75.0%)的判别准确率较高外,其余8个种群的判别准确率均较低,且综合判别准确率仅为63.4%,说明各种群之间的形态差异较小。主成分分析的结果表明,天津厚蟹和侧足厚蟹的10个种群基本重叠在一起,也说明它们之间的形态差异较小。差异系数值均小于亚种分类的阈值1.28。在宁波分布的天津厚蟹和侧足厚蟹种群中出现下眼缘隆脊(突起)介于二者之间的中间过渡类型,提示天津厚蟹和侧足厚蟹可能交配并产生后代。天津厚蟹和侧足厚蟹可能为同一个物种,建议将其作为亚种处理。

MORPHOMETRICAL STUDIES ON 10 POPULATIONS OF HELICE TIENTSINENSIS AND H. LATIMERA (CRUSTACEA, DECAPODA) FROM COASTS OF CHINA

Helice tientsinensis and H. latimera are among the most common crabs along the coast of China. They bur-row in muddy substrates of upper littoral and supralittoral zones, especially in habitats of deduced salinity such as salt marshes and estuaries. The identification of species mostly relied on the size, shape and number of infraorbital crest. However, the key morphological differences are variable within species and greatly differ between sexes, and the fe-males of both species could not be distinguished by the shape and number of infraorbital crest. Based on 33 proportional parameters of morphometric characters, three multivariation analysis methods were conducted to investigate the mor-phological variations among six populations (collected from Dandong and Panjin, Liaoning Province; Tanggu, Tianjin City; Rizhao and Weihai, Shandong Province; and Ningbo, Zhejiang Province) of Helice tientsinensis and four popula-tions (collected from Ningbo, Zhejiang Province; Quanzhou, Fujian Province; Beihai, Guangxi Province and Haikou, Hainan Province) of H. latimera. The results of cluster analysis could not make the two species separated. While the Quanzhou population of H. latimera was clustered into one group, the other nine populations were clustered into another group. Normalized Euclidean Distances of morphology of the ten populations indicated close relationship each other. Discriminant analysis demonstrated that there were no significant differences (total discriminant accuracy was only 63.4%) among the ten populations. The identification accuracies of discriminant functions of Quanzhou population and Tanggu population were 88.9% and 75.0% respectively, while those of the other populations were all low. Principle component analysis revealed that ten populations were almost overlapped to each other in scatter diagram of the first and the second principal components, indicating only small morphological variations among these populations. The coefficients of difference (CD) of proportional parameters of morphometric characters among the ten populations were always lower than 1.28, a well-known critical value of subspecies. Males with osculant infraorbital crest were found in Ningbo where had a mixed population of H. tientsinensis and H. latimera, suggesting that H. tientsinensis and H. latimera might cross in their sympatric populations. The conspecific status of H. tientsinensis and H. latimera was fur-ther supported by published and our unpublished molecular analyses. However, there do exist difference in the infraor-bital crest of male crabs. The infraorbital crest of populations north to Ningbo showed a pattern of H. tientsinensis, while those of southern populations showed a pattern of H. latimera. Therefore, we suggest to move both species down to subspecies level, i.e., Helice latimera latimera Parsis, 1918 and Helice latimera tientsinensis Rathbun, 1931.