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

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 transmissionelectron microscope. The exine ultrastructure of Classopollis corresponds to its complex external morphology. The exine canbe defined as regularly alveolate exine (on some regions as columellate exine). It consists of the following layers: the upperhomogenous layer, with uneven external and internal surfaces, the intermediate homogenous layer, the alveolate layer, and thelower homogenous one. Columellae and alveolae between them are more distinct at equatorial regions. This structure correspondsto striate ring that is visible through light microscope. A rimula (subequatorial canal) is presented by a sudden narrow thinningof exine between this columellate area and the distal side. Alveolae of the proximal exine are smaller and less regular in formthan those at equatorial region. Distal side of exine is thinner than proximal one. In the area of cryptopore the distal exine isdeprived of alveolae. The comparison of the present ultrastructural data and the data on fine morphology obtained by otherpalynologists affirms the similarity between the pollen under investigation and pollen of Cheirolepidiaceae.

Project Supported:

Clc Number:

Q913.84