Abstract
Deamia montalvoae sp. nov. (Cactaceae) from the Mesoamerican region (El Salvador, Guatemala, and Mexico) is described and illustrated based on morphological and molecular evidences. The new species is morphologically characterized by stems up to 2 cm in diameter, 7−8-ribbed, flowers (23−)27−30 cm long, with pericarpel covered by bristles and trichomes, but without spines; fruit 5−6 cm long and pale-red, covered by bristles and trichomes, with white flesh; seeds 3.1−3.5 mm long, dark brown, with a smooth microrelief. The phylogenetic analysis using two introns, rpl16 and trnL-trnF, and a spacer, psbA-trnH, shows that D. testudo is the sister species of D. montalvoae and D. chontalensis.