ESTUDIOS SOBRE MEGASPORAS PERMICAS ARGENTINAS. II. SUBLAGENICULA NUDA Y S. BRASILIENSIS DE LA CUENCA CHACOPARANENSE, ARGENTINA

Abstract

Two species of Sublagenicula are described for the fist time in subsurface strata of the Chaco-Paraná Basin. S. nuda (Nowak et Zerndt) Dybová Jachowicz is characterized by a prominent subgula and unornamented surface while its wall organization shows three ultrastructural zones with different arrangements in the wall units of the sexine. Nexine appears electronically denser and composed by parallellaminae. S. brasiliensis (Dijkstra) Dybová Jachowicz has a subgula, an ornamented surface with granules and bacules, and possibly the same ultrastructural organization. Comparisons with similar permian and pennsylvanian megaspores from Patagonia and U.S.A. were made showing, in the first case, some differences in the fine wall ultrastructure due to diagenetic processes, while in the second case some similitudes were observed in the external morphology and wall stratification. Finally, interpretations on the reproductived biology and dispersal methods of putative parental plants are made in order to show equivalent strategies in Lycophytes from different phytogeographic regions.