Sloanea ahuatoso n. sp., is described from material collected in the mountain range of Atoyac, Guerrero, and the Reserva de la Biosfera El Triunfo, Chiapas, Mexico. This species is characterized by its simple dichasial inflorescence, closed flower buds, fleshy sepals with dense tomentum abaxially, ellipsoidal capsules, and ellipsoidal seeds completely covered with an orange-colored aril. It is included in subgenus Quadrisepala for the inflorescence type and the closed flower buds. Its relationship with other species of the subgenus is discussed.
