Abstract. Croton balsensis (Euphorbiaceae), a new species endemic to the Balsas Depression of southern Mexico, is described and illustrated. It occurs in the states of Guerrero, Morelos, and Puebla, growing in tropical deciduous forest at elevations from 450 to 1850 m. It is best accommodated in Croton sect. Cascarilla. The Mexican species of this section are often quite similar, but C. balsensis is readily separated from related species by the possession of echinate ovaries and fruits.
Resumen. Se describe e ilustra Croton balsensis. Es endémica de la cuenca del río Balsas en el sur de México. Crece en los estados de Guerrero, Morelos y Puebla a altitudes de 450 a 1850 m en bosque tropical caducifolio. Pertenece a Croton sect. Cascarilla. Las especies mexicanas de esta sección por lo general son parecidas y C. balsensis se distingue por tener ovarios y frutos equinados.