下奥陶统反称笔石属(Anisograptus)的形态分异与分类

Morphologic Differentiation and Taxonomy of Anisograptus from the Lower Ordovician

根据安徽省宁国县胡乐地区的反称笔石属(Anisograptus)标本,参照国内外Anisograptus的25种及亚种的资料,发现反称笔石类的形态变化具有原始枝末端分支推迟和笔石枝密度缩减的特点,其中,部分种及亚种的胞管密度较大,与其他种类区别明显。因此,笔者等选择原始枝长度、分支密度、胞管密度为分类依据,将Anisograptus划分为如下5个种类:A.matanensis Ruedemann,A.ruedemanni Bulman,A.tetragraptoides Bulman,A.compactus Cooper和A.delicatulusCooper。

The specimens from the Hule area of Ningguo County, Anhui Province and the data of all known 25 species and subspecies in the world shows that Anisograptus has apparent morphologic differentiation in the length of primary stipes, the spacing of dichotomies and the density of thecae. Therefore, this paper selects these three morphologic characteristics as the principle for the taxonomy of Anisograptus. Accordingly, Anisograptus is here divided into 5 species, i.e. A. matanensis Ruedemann, A. ruedemanni Bulman, A. tetragraptoides Bulman, A. compactus Cooper, and A. delicatulus Cooper.