Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia.

The morphology and structure of megaspores assigned to Lagenoisporites magnus from the Toregua Formation, Retama Group, mid-upper Tournaisian of Bolivia were studied. The analysis was performed with light, fluorescence and scanning electron microscopy. Megaspores were laterally compressed and presented a spherical body with a proximal gula, of the hologula type.

Isoetes pedersenii, a new species from Southern South America.

The name Isoetes pedersenii H.P. Fuchs (Lycophyta), a species known only from the Mburucuyá National Park, Corrientes, Argentina, is validated.

Morphology and ultrastructure of megaspores and microspores of Isoetes sehnemii Fuchs (Lycophyta).

The morphology and wall ultrastructure of megaspores and microspores of Isoetes sehnemii that grows in Brazil were analyzed as part of the study of the Isoetaceae present in Southern South America. The observations were performed with light, scanning and transmission electron microscopes. The megaspores are trilete, 350-450microm in equatorial diameter.