Major part of micropaleontological knowledge of the Pelotas Basin is related to calcareous microfossils, justifying a systematic survey on the palynological data. This paper presents the taxonomic results from the study of 535 stratigraphic samples of two wells drilled in the offshore portion of the Pelotas Basin, enclosing Cretaceous to Neogene deposits. Palynological assemblages analized are diverse and abundant, consisting of spores (mosses and ferns), pollen grains (gymnosperms and angiosperms), dinoflagellate cysts, palynoforaminifers, scolecodonts and fungal spores. As a result of the large volume of generated data, it was necessary, for effect of publication, the compartimentation of the information. In this first part, dinoflagellate cysts Peridiniales Order are presented, with descriptions and photomicro-graphs. Among the 220 taxa identified of dinoflagellate cyst, 76 belong to the Peridiniales Order, attributable to 31 genera, 72 species, a subspecie, beyond two taxa described without specific determination. A considerable number of 24 species reported for the first time for Brazilian basins is highlighted. Biostratigraphic and paleobiogeographic considerations are synthetically discussed, based on the associations recognized for Late Cretaceous and Neogene in American Atlantic margin and regions close to the Antartic Polar Circle.

Universidade Federal do Rio Grande do Sul