A new species of Acanthaceae, Justicia guerrerensis, is described from a limited region of the state of Guerrero in southwestern Mexico. In several morphological characters, it resembles J. ixtlania, a widespread species that occurs in several states to the northwest of Guerrero. A key is presented to distinguish these two species. Images of the holotype and macromorphological features of J. guerrerensis are provided. Additional comparisons between J. guerrerensis and J. ixtlania via SEM images of pollen and a distribution map are also provided.
