Palynological assemblages present in Los Monos (Devonian) and Itacua (Lower Carboniferous) formations at Balapuca (Tarija basin), southern Bolivia. Part One. Los Monos Formation

Abstract

Two associations of palynomorphs recovered from eight samples from Los Monos Formation (late Eifelian-early Frasnian), cropping out at Balapuca, located at the Bolivian margin of the Bermejo River in the San Telmo range, are characterized. In the Tarija Basin, this unit overlies the Pescado (or Huamampampa) Formation (Emsian-Eifelian) and underlies the Iquiri Formation (Frasnian-Famennian), when it is preserved. The studied section is mainly composed of grey laminated or massive pelites and sandstones with current structures or bioturbation. Paleoinvertebrates and fossil plant debris were recovered from different levels, and some of them yielded palynomorphs. The whole microflora here presented is composed of 76 species, of which trilete spores are dominant and acritarchs, prasinophytes, cryptospores and chitinozoans are subordinately present. Two new species of spores, Leiotriletes balapucensis and Endoculeospora altobellii, both belonging to the youngest assemblage, are described. Two assemblages are recognized based on the stratigraphical distribution of diagnostic species, one attributed to the late Eifelian and the other to the late early Givetian to late Givetian. Both associations share several species with other coeval microfloras mainly from Argentina, Bolivia, Brazil, and beyond South America, from North America and western Europe.