The classification of the species of Old World species of Passiflora (subgenus Decaloba, supersection Disemma, Tetrapathaea, and Hollrungia) has been historically unresolved. Molecular and morphological data were used to examine the evolutionary relationships in this group. Two clades are supported: first, subgenus Decalobasupersection Disemma, and second, a clade representing a new subgenus with three species, Passiflora tetrandra, P. aurantioides, and P. kuranda.
Supersection Disemma is monophyletic, containing an Asian section, Octandranthus, and an Australian section, Disemma. Passiflora hollrungii (section Hollrungiella) from Papua New Guinea is resolved ambiguously. In section Octandranthus three species exhibit variation in stamen and carpel number. Passiflora tonkinensis (=Passiflora moluccana var. glaberrima) and P. siamica, were investigated to determine mode of development and the mechanism behind the anomalous growth. Passiflora siamica develops additional stamens through dédoublement of a single widened stamen primordium. Passiflora moluccana var. glaberrima exhibits congenital dédoublement where stamens arise from the floral apex already doubled.
The second lineage consists of P. tetrandra (= Tetrapathaea tetrandra) and P. aurantioides(= Hollrungia aurantioides). Additionally, a new species of Passiflora( P. kuranda) was identified. Tetrapathaea tetrandra, H. aurantioidesand P. kurandaform a monophyletic lineage sister to subgenus Decaloba. These species are recognized here as part of Passiflorasubgenus Tetrapathaea, raising the number of subgenera in Passiflora from four to five.
A revision of subgenus Decaloba supersection Disemma is also presented. A dichotomous key to the supersection and sections is provided along with detailed morphological descriptions of each species. Information about species distributions, ecology, pollination, and herbivory are provided.
Lastly, a preliminary analysis of nectary development and expression in Passiflora was completed. CRABS CLAW (CRC) was chosen as a candidate gene for an evolutionary developmental analysis of nectary evolution in Passiflora.Gene expression in both floral and extrafloral nectaries was examined in three species. CRC was expressed in all floral nectaries and none of the extrafloral nectaries. Genomic CRC was cloned and seven distinct copies are present in P. morifolia and P. tricuspis, while only two copies are present in P. perakensis.The cladograms of genomic and cDNA transcripts of CRC are congruent.