A Taxonomic Revision of Passiflora sect. Xerogona (Passifloraceae) Using Principal Component Analysis

In subgenus Decaloba (DC.) Rchb. of Passiflora L., the section Xerogona (Raf.) Killip (Passifloraceae) is a group of herbaceous vines found in subtropical and tropical regions of the Americas. Primarily distributed in Central America, with a few also found in the West Indies and South America, the species of Passiflora sect. Xerogona are recognized by their unusual dehiscent capsular fruit, the absence of bracts and laminar nectaries, and their transversely grooved seeds. Passiflora tenella Killip is the only species included in Passiflora sect. Xerogona with a fruit that does not appear to be a capsule, but the shape of the leaves and the absence of floral bracts and laminar nectaries suggest affiliation with this section. Fifteen species, including two subspecies, are recognized within Passiflora sect. Xerogona. Passiflora cobanensis Killip is distinguished as two subspecies, P. cobanensis subsp. cobanensis and P. cobanensis subsp. brevipes (Killip) T. Boza, with the latter subspecies transferred from P. brevipes Killip. From previous species circumscriptions, this section contains two problematic species complexes for P. capsularis L. and P. rubra L. The morphological variation between and within these two species complexes was examined in this study, using Principal Component Analysis and correlation matrices of morphological characters, and this variation was studied throughout their distributional ranges. Passiflora capsularis is recognized as a single variable species. Two species are recognized within the P. rubra complex, based primarily on floral characters, as P. cisnana Harms and P. rubra. Passiflora cisnana is lectotypified.