Occurrence of the genus Galeacornea (elaterate pollen) at the Cretaceous of central-western Argentina

MEGO, N.; PRÁMPARO, M.B.; NARVÁEZ, P.L

Salvador

Congreso; XIV International Palynological Congress - X International Organisation of Palaeobotany Conference; 2016

Universidade Estadual de Feira Santana

Elater-bearing taxa are characteristic of the Albian-Cenomanian Elaterate Province corresponding to northern South America, Central and North Africa and the Arabian Peninsula. Species of the elaterate complex occur in high abundances and diversity only in the circum-Atlantic basins. A new elaterate species named Galeacornea guayaguensis Prámparo, Narváez and Mego, has been recently described from sediments of the Lagarcito Formation (San Luis Basin) at the ?La Yesera Sur? section, Sierra de Guayaguás ranges, San Juan Province, central-western Argentina. The psamopelitic-evaporitic sequence with gypsum and anhydrite intercalations yields a rich palynoflora of continental origin (fluvio-lacustrine). G. guayaguensis shares with other Galeacornea species the shape of the grain, the presence of an annular rim and the distal appendages. The ridge-like appendages are similar to those of G. stoveri and G. tarimensis, although they never fuse with the annular rim or with each other at their ends as it respectively occurs in other species. The new species from Argentina provides further evidence on the morphological variation of elaterate grains and extends the geographical distribution of the genus Galeacornea to South America midlatitudes, far beyond the palaeophytogeographic Albian?Cenomanian Elaterates Province of the equatorial region. However, it is important to note, that elaterates in Argentina are less diverse and abundant than at lower latitudes. Several studies suggest that elaterates and polyplicate pollen are botanically related. At the Lagarcito Formation Galeacornea guayaguensis was found within an association dominated by gymnospermous elements, mainly represented by polyplicate (diverse and abundant Ephedripites, Gnetaceaepollenites, Steevesipollenites) and rimulate grains (Classopollis). An Aptian-Albian range was estimated for the palynologic association recovered in the studied area, based on the occurrence and biostratigraphical value of different verrucate spores. It is remarkable the presence of Reyrea polymorphus Herngreen, a significant marker taxon from the early?middle Albian of Brazil, associated with the new elaterate species in central-western Argentina.