The new species Castilleja eggeri (Orobanchaceae) is described, compared and illustrated. The species is distinguished by its reduced number of 1–5 flowers per inflorescence, decumbent stems and dissected leaves. It is distributed in a narrow and very humid area of cloud forest in the mountains of central Veracruz in eastern Mexico. It is compared with Castilleja moranensis, morphologically the most similar species. Conservation assessment classifies the species as critically endangered (CR). Also, a key and distribution map of Castilleja taxa in the state of Veracruz are provided. This species is added to the endemisms of Castilleja in Mexico, where one third of the total diversity of the genus in the Americas is found.

Keywords: Castillejinae, hemiparasitism, parasitic species, Scrophulariaceae