Floral biology and pollination of two sympatric species of Galipeinae (Galipeeae, Rutaceae) endemic to the Brazilian Atlantic Forest

•The floral biology and pollination of two species of Galipeinae are studied.•Angostura bracteata have day- and night-active pollinators, notably lepidopterans.•Conchocarpus macrophyllus is most frequently pollinated by butterflies.•Despite pollinator sharing among species, heterospecific pollen transfer is unlikely.•Pollen-presenting staminodes are reported for the first time in Rutaceae. Galipeinae is the most diversified group of neotropical Rutaceae, presenting a wide floral diversity. However, the floral features in the species of the group have rarely been studied, hindering the understanding of functional aspects of particular floral attributes in relation to the biology. In this study, we investigate the floral biology and pollination of Angostura bracteata and Conchocarpus macrophyllus (Galipeinae), which are co-flowering and sympatric species occurring in the Atlantic forest of southeastern Brazil. Both species have tubular, nectar-rewarding, monosymmetric flowers, with two fertile stamens on the posterior side of the flower and five anterior staminodes. C. macrophyllus is most frequently pollinated by butterflies and less frequently pollinated by medium-sized bees. A. bracteata is also frequently pollinated by butterflies, shared, in part with C. macrophyllus, and less frequently pollinated by settling moths and by hummingbirds. Since we found that butterflies transfer the pollen grains of C. macrophyllus and A. bracteata through different body parts, it is unlikely that interspecific pollen mixture occurs, despite pollinator sharing. Although functionally generalized, most floral features indicate specialization for pollination by lepidopterans in both species. So, the related floral attributes consist of a long and narrow floral tube, as well as delicate landing platforms, and nectaries that produce minute quantities of dilute nectar, among others. Functional staminodes presenting pollen secondarily in the ventral region of the flower in A. bracteata are herein reported for the first time for Rutaceae, which results in a wider spatial presentation of pollen and may also increase the accuracy of sternotribic pollination. In C. macrophyllus, the staminodes bear pollen-collecting hairs, which may avoid spontaneous self-pollination or serve to scrape pollen from the tongues of pollinators. Our results indicate that the function of staminodes in the biology of the species may have influenced their maintenance throughout the floral evolution of Gali