The genus Streblacanthus is currently recognized by four species with a distribution ranging from Southern Mexico to Northeastern Argentina. Previous molecular phylogenetic analyses support the monophyly of Streblacanthus and its position in the Tetramerium lineage. In this study, I infer species relationships within Streblacanthus using a combination of the trnL-F (chloroplast) and ITS (nuclear) genes. 15 taxa representing different populations of the 4 currently recognized species are sampled along with one additional taxon that is considered a new species. Additional notes on morphology, including pollen structure, are discussed and their phylogenetic utility is addressed.

Key words: Acanthaceae, ITS, molecular phylogeny, phylogeny, Streblacanthus, trnL-F