This paper describes a new species of Sphenophyllum (S. paranaensis n. sp.) from the Rio do Rasto Formation, Serrinha Facies, cropping out along the Dorizon-Paulo Frontin road (State of Paraná, Brazil), 1.5 km south of the main church of Dorizon. The new species is based on isolated leaves, verticils and articulated stems. A few lascinated leaves which occur dispersed at the same outcrop may be interpreted as a polymorphic variation of the new species, but until further data become available they are here called Sphenovhyllum cf. S. thonii, In fact, both forms of this genus from Dorizon are similar to specimens assigned to S. thonii in África but smaller than type material of this species
