论克拉梭粉外壁的超微结构：西伯利亚侏罗纪的一个孢体

ON THE ULTRASTRUCTURE OF CLASSOPOLLIS EXINE: A TETRAD FROM THE JURASSIC OF SIBERIA

通过对西西伯利亚西南部某钻孔中侏罗统上部(Callovian，Tyumen组)所获得的一个Classopollis的四孢体光学显微镜和切片的透射电镜观察研究后认识到，Classopollis的外壁超微结构与它复杂的外部形态一致。外壁由几层组成：上部均质层，具不平的外、内表面，中间均质层，穴状层和下部均质层。在它们之间的柱状体和穴在赤道区更明显。这种结构与光学显微镜下所见的条纹圈相当。环沟(亚赤道沟)是由柱状区和远极面之间的外壁突然变薄形成的。近极区的穴较之赤道区的要小且形状较不规则。外壁远极面较近极面为簿。远极面隐孔区无穴。比较表明此种花粉与掌鳞杉科花粉形态相似。

A tetrad of Classopollis sp. from the southwestern region of Western Siberia (borehole Yarskaya 3, near city Tyumen) in the upper Middle Jurassic (Callovian Tyumen’ Formation) was investigated using light microscope and transmission electron microscope. The exine ultrastructure of Classopollis corresponds to its complex external morphology. The exine can be defined as regularly alveolate exine (on some regions as columellate exine). It consists of the following layers: the upper homogenous layer, with uneven external and internal surfaces, the intermediate homogenous layer, the alveolate layer, and the lower homogenous one. Columellae and alveolae between them are more distinct at equatorial regions. This structure corresponds to striate ring that is visible through light microscope. A rimula (subequatorial canal) is presented by a sudden narrow thinning of exine between this columellate area and the distal side. Alveolae of the proximal exine are smaller and less regular in form than those at equatorial region. Distal side of exine is thinner than proximal one. In the area of cryptopore the distal exine is deprived of alveolae. The comparison of the present ultrastructural data and the data on fine morphology obtained by other palynologists affirms the similarity between the pollen under investigation and pollen of Cheirolepidiaceae.