Systematics

Arremon castaneiceps is monotypic.

Olive Finch (Arremon castaneiceps) previously has been placed in two different genera. It was described as Buarremon castaneiceps (Sclater 1859). By the early 20th century, Olive Finch and Sooty-faced Finch (Arremon crassirostris) had been transferred to the genus Lysurus on the basis of similarities in plumage, voice, behavior, and microhabitat (Ridgway 1901). These two allopatric taxa of Lysurus always have been recognized as separate species, although Hellmayr (1938) mentioned that perhaps they should be considered conspecific.

Recent molecular phylogenetics work has supported the sister relationship between the Olive Finch and Sooty-faced Finch (Cadena et al. 2007, Klicka et al. 2014). Additionally, these phylogenetic studies showed that Buarremon was not monophyletic with respect to Arremon and Lysurus (Cadena et al. 2007, Klicka et al. 2014). Therefore the two species of Lysurus, Olive Finch and Sooty-faced Finch, have since been transferred to Arremon. Together, these two species are much more closely related to Chestnut-capped Brushfinch (Arremon brunneinucha) and Green-striped Brushfinch (Arremon virenticeps) than to other species of Arremon (Klicka et al. 2014).