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Abstract

Petunia littoralis is endemic on the Santa Catarina coast. This study evaluated the abundance and reproductive biology of P. littoralis on the Praia da Joaquina dunes. The species did not occur on the beach and was distributed from the frontal dune to the slacks, where the species was more abundant. The flowering period lasted ten months, with a peak in the spring. The reproductive branches were 33,94cm long (SD=25,75) on avarage and bore 5,87 flowers (SD=3,87). Rarely, there was more than one open flower/branch and each flower lasted one or two days. P littoralis is autoincompatible and did not form fruits by spontaneous autopollination (n=26), manual pollination in the same flower (n=20), or pollination between flowers in the same plant (n=5). The fruit set with manual cross-pollination was 85% (n=20) and the control was 87% (n=71). The S/O ratio was 71%. Among eight of the flower' visiting insects, the females of Hexantheda missionica (Hymenoptera: Colletidae) seemed to be the most effective pollinators. This bee species seems to visit Petunia spp. flowers, and allied genera exclusively, suggesting an oligolectic character. When transferring the pollen to the hind legs and to the abdomen, the bee makes contact with the stigma ventrally. The male bees collect nectar, rest in the flower, and patrol patches of P. littoralis. A mating in the flower was registered during this study.