Phylogenetic conservation and shifts of pollination niche in generalist epiphytic cacti

•The main pollinator of Rhipsalis were bees.•Pollination systems in Rhipsalis combine a phenotypic floral generalization and functional pollinator group specialization.•Rhipsalis shows in a positive phylogenetic signal for pollinating niches.•The ancestral pollination niche for Rhipsalis is defined by short-tongued small bees.