Rubiacearum Americanarum Magna Hama Pars XLVIII: A New View of Palicourea sect. Axillares and Description of Some New Species (Palicoureeae)
Many of the species classified in Psychotria L. subg. Heteropsychotria Steyerm. (Rubiaceae), including the species of Psychotria ser. Axillares (Hook. f.) Steyerm., have been shown to belong to Palicourea Aubl. based on morphological and molecular characters. This section is now treated as Palicourea sect. Axillares (Hook. f.) Borhidi, and includes 14 species found from southern Central America through the Andes of northwestern and western South America with a center of diversity in eastern Colombia and western Venezuela. This section is characterized by the combination of laminar, well-developed, bilobed stipules and mostly capitate, pseudoaxillary or sometimes terminal, mostly sessile inflorescences with numerous well-developed bracts that enclose the flowers but without enlarged involucral bracts. It is circumscribed differently here than it is by Borhidi. The nomenclatural summary, key, and diagnostic discussions that separate the species included here are based on several new taxonomic circumscriptions. No infraspecific taxa are recognized in Pal. axillaris (Sw.) Borhidi, but one of its varieties from Venezuela is raised to species status as Pal. villipila (Steyerm.) C. M. Taylor. The circumscription of Pal. rosacea (Steyerm.) Borhidi is expanded, and four species are newly described here: Pal. aristata C. M. Taylor from the Andes of southern Ecuador, Pal. quibdoana C. M. Taylor from northwestern Colombia, Pal. santanderiana C. M. Taylor from the Andes of eastern Colombia, and Pal. winfriedii C. M. Taylor from northern Venezuela.