The subgenus Decaloba (Passifloraceae) is poorly studied on reproductive aspects, which may help our understanding on phylogenetic relationships in the genus. The purpose of this work was to study the reproductive biology and pollination of Passiflora pohlii and P. capsularis, two species belonging to this subgenus with occurrence in Minas Gerais state. Stigma receptivity, pollen viability and nectar concentration were determined. Controlled pollination experiments were done to assess the breeding system. Floral visitors and pollen load were observed. In both species, the flowers start to open during the night. P. pohlii anthesis begins about 3:00 a.m. and its senescence about 11:00 a.m.; the flowers of P. capsularis opened about 3:00 a.m. and closed about 2:00 p.m. The concentration of the nectar and viability of the pollen had been, respectively, 34.88 ± 7.66% and 80 ± 0.15% in P. pohlii and 22.33 ± 5.82% and 92 ± 0.06% in P. capsularis. Passiflora pohlii was xenogamous and self-incompatible and P. capsularis autogamous and self-compatible. Passiflora pohlii had as pollinators three species of Ptiloglossa (Colletidae) and in P. capsularis all observed visitors were considered nectar and pollen thieves. The nocturnal anthesis showed by studied species of Passiflora suggests an evolutionary relationship among Passiflora subg. Decaloba and hymenoptera, especially Ptiloglossa bees.
bees; floral biology; nocturnal anthesis; pollination; Ptiloglossa
