我国Hirnantian期dalmanitid类三叶虫分类问题的初步探讨——从聚类分析角度分析分类中所存在的问题

PRELIMINARY DISCUSSION ON THE TAXONOMIC PROBLEM OF THE DALMANITID TRILOBITE IN THE HIRNANTIAN AGE , CHINA ——CAREFUL OBSERVATION SHOWS PROBLEMS IN THE TAXONOMY RETRIEVED FROM CLUSTER ANALYSIS OF VIEW

我国己发现产达尔曼虫类(dalmanitid)三叶虫的地区遍及全国14个省(市),32个产地,包含3个属22个种(含4个未定种),其不仅是组成Hirnantian期动物群中的重要分子,而且是我国华南地区奥陶系与志留系之间分界的重要标志性化石,并成为我国与外国相关地层进行划分和对比的主要依据之一。因而得到国内、外学者高度重视和关注,但对该类三叶虫的分类,仍然存在一些问题,如出现异地定名、同物异名等现象,至今还没有人做过较全面的整理和修订工作。文中根据前人己发表的16个属种,采用多变量的比值数据,通过聚类分析方法,对我国Hirnantian期中达尔曼虫类三叶虫做初步整理和修订,将16个种合并成5个种,分别归属予两个属——Songxites wuningensis Lin,1981,Songxites ovata(Qu),Mucronaspis nanchengensis(Lu),Mucronaspis yichangensis(Lin)和Mucronaspis mucronata(Brongniart)。

In the present paper, the method of ＂Q-mode cluster analysis＂ is used in a taxonomic study of 16 cephala belonging to dalmanitid species （subspe- cies） of the Hirnantian Age in China. The statistical measurement of similarity is the incremental sum of error squares （AE）. Here, author uses the variables in ratio form. The transformative method of standardization is adopted in the process of original data. The resemblance relation matrices of all specimens are formed through calculation of the increments of sum of error squares between all speci- mens （see Table I ）. Finally the two-dimensional dendrogram is drawn by stepwise calculation （see text-fig. 1）.