An isopod from the Codó Formation (Aptian of the Parnaíba Basin), Northeastern Brazil

Abstract

The Codo Formation is a lithostratigraphic unit with predominant carbonate sedimentation of the Aptian age situated in the intracratonic Parnaiba Basin. In this formation, the only known crustaceans were conchostracans and ostracods. Systematic collections conducted in the Brejo city, in the Maranhao State, have provided new taxa for the cited lithostratigraphic unit. A new genus and species of isopod is described with the following set of features: cephalon elliptical deeply inserted in the first pereionite; eyes located dorsolaterally; body oblong oval; and isomorphic pereionites and pleonites, which indicate an affinity with the family Archaeoniscidae. The presence of this taxon in the limestone deposits from the Codo Formation reinforces prior inference of a lacustrine/marine paleoenvironments, and indicates a greater diversity of aquatic arthropods during the opening of the South Atlantic in the Early Cretaceous.