Nocturnal mammals, diurnal lizards, and the pollination ecology of the cryptic flowering Acrotriche serrulata (Ericaceae)

Acrotriche serrulata exhibits a complex and uncommon form of flowering. It starts with a male-phase flower that shows secondary pollen presentation on the perianth and follows with a female phase after the corolla is removed or abscissed. We examined the potential for insects, lizards, and mammals to act as pollinators. Observations and experiments on breeding system, phenology, floral scent, flower visitors, and lizard feeding were undertaken in southern Australia. Acrotriche serrulata sets little fruit by autonomous selfing but readily sets fruit after facilitated geitonogamy and xenogamy. Flower anthesis is diurnal and nocturnal. The nectar profile includes acetaldehyde, ethanol, and ethyl acetate. The nocturnal mammals Trichosurus vulpecula and the introduced Rattus rattus were the only visitors observed to actively forage on the flowers. In contrast, the skinks Egernia whitii, Niveoscincus ocellatus, and Niveoscincus metallicus routinely passed flowers full of nectar and foraged only on those presented during feeding observations. Insects visited the flowers but did not behave as pollinators. Acrotriche serrulata is likely to be pollinated by nocturnal mammals attracted to its flowers by scent. Effective pollinators appear to be rare over some of its range. This may have implications for the long-term reproductive success and conservation of A. serrulata.