A New Extrafloral Nectary-Bearing Plant Species in the Brazilian Savanna and its Associated Ant Community: Nectary Structure, Nectar Production and Ecological Interactions

Abstract

Brazilian Savanna stands out for the large number of species with extrafloral nectaries (EFNs) with high morphological diversity. In Smilax polyantha (Smilacaceae), the base of the petiole showed a slight secretion and great visitation by ants suggesting the presence of an EFN. In this way, we aimed to determine the ant community associated with this plant, as well as to identify and characterize this unsuspected structure and determine the phenology and liquid production of this tissue. The study was carried out in a Cerrado area, in Uberlândia, Brazil. Ten individuals were used for the anatomical analysis and histochemical tests and the EFNs secretory activity was monitored, being categorized into active and non-active EFN. In addition, the volume and sucrose concentration were determined from three nectaries of ten individuals, and individuals of ants found foraging on these nectary were collected, day and night. Results showed a large amount of extrafloral nectar secretion and the EFN tissue is composed of a few cell layers that showed positive reactions for proteins and reducing sugars. We recorded a significantly correlation between percentage of EFNs activity and abundance of ants. The secretory activity is concentrated in September and ten ant species, of five subfamilies, were identified foraging on the EFNs.