The exine ultrastructure of the Permian pollen genus Plicatipollenites Lele 1964

The fine morphology of Plicatipollenites malabarensis (Potonié and Sah) Foster, 1975 from the Early Permian Al Khlata Formation, Oman was studied using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A ‘crochet-like’ sculpture is visible on both sides of the corpus in SEM. On ultramicrographs, this sculpture is distinguishable as a thin undulating ectexinal layer. The darkened area around the proximal trilete scar visible in transmitted light reflects a slight endexinal thickening in that area. The reticulate ornament of the saccus seen in LM is a result of superimposed superficial folds and inner ectexinal partitions. The saccus is filled with ectexinal partitions, many of which are radially orientated; its protosaccate appearance might be due to compression. The endexine is prominent and homogeneous. However, the presence of several indistinct lamellae in a less compressed region implies the originally lamellate form of the endexine. Morphological data on Plicatipollenites gondwanensis (Balme and Hennelly) Lele 1964 from the same deposits and Cordaitina Samoilovich, 1953 from the Permian of Russia (Kungurian of Cis-Urals and Kazanian of Siberia) are used for comparison. These taxa are similar in the corpus sculpture, thick, apparently homogenous but ontogenetically lamellate endexine. Differences between Plicatipollenites and Cordaitina include the presence of an endexinal fold encircling the corpus in the former genus and certain dissimilarity in the ultrastructure of the proximal scar. Nonetheless, both genera show a complicated ultrastructure of the proximal scar region implying that the scars might have served as apertures.