The First Permineralized Microsporophyll of the Glossopteridales: Eretmonia macloughlinii sp. nov.

Abstract

Eretmonia du Toit is a microsporophyll genus attributed to the Permian Glossopteridales. Microsporophylls are scale leaves (smaller leaves with morphology similar to that of Glossopteris leaves) that bear clusters of sporangia at the end of stalks attached to the petiole of the sporophyll. Late Permian permineralized specimens of Eretmonia from the central Transantarctic Mountains in Antarctica reveal the first anatomical information of the genus. Numerous veins run the length of the petiole and alternate with large canals/air spaces; the veins and canals are separated by increasing amounts of parenchyma. The ground tissue of the leaves is composed of isodiametric parenchyma of varying diameters. Beneath the epidermis is a hypodermis two to three layers thick. Pollen sac walls are a single layer thick with a tapered apex and bulbous base. The simplicity of the bisaccate pollen grains does not suggest a specialized form of pollination but rather that the glossopterids were wind pollinated.