A new taxonomic and systematic approach on the Gondwana genus Portalites Hemer and Nygreen 1967

Abstract

Portalites is a Gondwanan organic-walled microfossil, especially found in Carboniferous and Lower Permian coal beds and associated strata. The genus is represented by three species: Portalites confertus (type species), Portalites gondwanensis and Portalites baculus, described from Saudi Arabia, Brazil and Argentina, respectively. In this paper we present a detailed morphological analysis of the main features of this genus, including (i) spore diameter, (ii) wall structure and thickness, (iii) ornamentation pattern, and (iv) presence, quantity and size of pores (functional and non-functional ones). The material comprises well-preserved specimens, analysed with optical microscopy and scanning electron microscopy, derived from the Paraná (Rio Bonito Formation) and Amazonas (Monte Alegre and Itaituba formations) basins, Brazil, ranging from the Pennsylvanian to the Cisuralian. Although we have observed a very close resemblance with coeval genera Arabisphaera and Spongocystia, the presence of a main pore, from which a channel is developed beyond the spore wall, distinguishes Portalites from these taxa. Species of Portalites exhibit a clear variation in some morphological features, mainly in ornamentation pattern and, secondly, in overall diameter and wall thickness. A new diagnosis is given for Portalites, as well as amendments in the diagnosis of P. gondwanensis. We present the first reports of P. confertus and P. baculus in Brazil, as well as spores with presumed fungal morphological structures, confirming its biological affinity.