Cantua is a small but complex genus in the Polemoniaceae subfamily Cobaeoideae. The species have Andean distributions, and are characterized by their shrubby or diminutively arborescent habits, dimorphic shoots, and pantoporate pollen. Comparative gene sequencing of the species has been undertaken for three regions of the chloroplast genome (trnT - trnL 5' and trnL 3' - trnF spacer regions, and partial ndhF coding region) and the internal transcribed spacer region of nuclear ribosomal DNA to help elucidate relationships within the genus and among members of the subfamily Cobaeoideae. In a recent classification, the genus Huthia was subsumed in Cantua, but no phylogenetic data have been applied to this problem. Our phylogeny suggests that Cantua is paraphyletic to the former genus Huthia, and that C. (Huthia) coerulea is sister to C. quercifolia. This result is consistent with the recent nomenclatural changes. A preliminary study of the pollen morphology using scanning electron and light microscopy corroborate the molecular results. Among Cantua species, C. quercifolia and C. coerulea share the pollen synapomorphy of irregularly spaced verrucae on their areolate semitectate sexine.

Key words: Cantua, Huthia, Polemoniaceae