Palynological studies in central Amazonia are scarce, especially those concerned with resolving the age of sedimentary deposits. A recent opportunity allowed the stratigraphical and palynological study of a sedimentary unit below the Negro River's current channel. Age was constrained by the basal occurrence of Alnipollenites verus, and the top occurrence of Grimsdalea magnaclavata and Paleosantalaceaepites cingulatus, as late Pliocene to early Pleistocene. Here, we provide additional details on the palynostratigraphy and biodiversity of this deposit. Samples yielded 95 palynomorphs that included 58 pollen and 26 spore species, of which we identified botanical affinities with 26 angiosperm, one gymnosperm and four pteridophyte families. Twenty-five new taxa are erected, from which we recognise five angiosperm genera, namely Pacourina/Vernonia (Asteraceae), Myrsine? (Myrsinaceae), Symmeria (Polygonaceae), Faramea (Rubiaceae) and Schefflera (Araliaceae), plus a possible Marcgraviaceae pollen. These taxa, along with the majority of the recovered assemblage, are indicative of Amazonian lowland floras.