"Arcytophyllum" is a monophyletic genus when "A. serpyllaceum" is excluded, as this species has been shown to be more closely related to "Bouvardia" but has not been formally transferred to another genus.The remaining species are most closely related to the North American and Caribbean genus "Houstonia" (including "Stenaria") and one species of the polyphyletic genus "Oldenlandia" ("Oldenlandia microtheca") distributed in Mexico and Central America, indicating that "Arcytophyllum" may be one of the few cases in the family Rubiaceae of a southward migration to reach the Andes.