Myrmecophilic food body production in the understorey tree, Ryparosa kurrangii (Achariaceae), a rare Australian rainforest taxon.

Plant food bodies are rarely observed in the field, because of continual harvesting, and are often first documented on isolated glasshouse plants. Little is known about the genus Ryparosa (Achariaceae), and the appearance of outgrowths on leaves and stems of glasshouse-raised R. kurrangii seedlings suggested that the species may produce food bodies. Detailed macroimaging and histological techniques were used to characterize chemomorphological variation in food body material gathered from glasshouse plants. Two distinct types of food body were observed. Multicellular pearl bodies derived from epidermal and mesophyll tissue were produced on young leaves and stems, and contained lipids and glycogen-like carbohydrates. A unique form of lipid-rich multicellular food body that 'opens' during development was found exclusively on mature plant tissue. A filament network was associated with food body lipid droplets. This is the first detailed documentation of food body production in an understorey genus adapted to low light conditions. We suggest that the distinctive spatial deployment of Ryparosa food rewards, and the ants attracted to them, may be invaluable for keeping long-lived leaves free from epiphyllous communities.