The Margarornis assemblage includes four genera: Margarornis, Premnoplex, Premnornis, and Roraimia, all thought to be closely related. Differences in vocalizations and habitat use between Premnoplex brunnescens (Spotted Barbtail) and P. tatei (White-throated Barbtail) are consistent with their full species status. In light of the weak anatomical (hindlimb musculature) evidence supporting the inclusion of Premnornis in the Margarornis assemblage, the convergence-prone nature of characters associated with climbing habits, and the differences in their nests and foraging behavior, I propose that Premnornis is not a member of the Margarornis assemblage and that Premnoplex is closely related only to Margarornis. These results are supported by recent molecular phylogenetic analyses. Although Roraimia differs in plumage, tail shape, and song from other members of the Margarornis assemblage, it must be provisionally included in the assemblage until evidence clarifies its phylogenetic position.