A new species of Thoreauea J. K. Williams is proposed. This species differs from Thoreauea paneroi J. K. Williams in its corolline crown 10-lobulate at the apex and stamens as long as the crown. The species described in this paper was found in habitats of forests of Pinus L., Quercus L., and Abies Miller and in montane rain forest found in the highest region of the Sierra of Guerrero. The fruits and seeds are described for the first time for this genus.