The lastreopsid ferns are a group of mostly terrestrial ferns within the Dryopteridaceae, found in parts of Africa, Madagascar, the Neotropics, southern Asia, Australasia, and some Pacific Islands. Within this group is the paraphyletic genus Lastreopsis s. l., which has been segregated into Lastreopsis s. s. and Parapolystichum. However, there remain several incertae sedis species of Lastreopsis s. l. awaiting phylogenetic analysis to determine their correct generic placement. This study examined six incertae sedis species, using new sequence data from a total of 14 species (18 specimens) of Lastreopsis s. l. The phylogenetic analyses revealed that two of the six incertae sedis species are members of Lastreopsis s. s., and four fall within the newly segregated genus Parapolystichum. Two of the species in Lastreopsis s. s. form a “vieillardii” group that is sister to Lastreopsis subg. Rhopalotricha. Given its phylogenetic position and the shared spore ornamentation, the taxa in the “vieillardii” group are assigned to Lastreopsis subg. Rhopalotricha. The new accessions derive from Australasia and the Pacific. Their inclusion does not alter existing relationships in Lastreopsis s. s. or Parapolystichum. The Bayesian search supported a monophyletic Lastreopsis s. s. (in contrast to previous studies that recovered the clade, but lacked support), and in Parapolystichum, all of the new accessions were nested in an Australasian group. New combinations are provided for Parapolystichum calanthum, P. grayi, P. kermadecense, and P. pacificum, and a revised description of Lastreopsis subg. Rhopalotricha is provided.