Evolutionary Trends and Specialization in the Euglossine Bee–pollinated Orchid Genus<i>Gongora</i>^1,²

Abstract

The family Orchidaceae exhibits some of the most diverse and intricate modes of animal pollination across angiosperms. Highly specialized pollination by male euglossine bees (Apidae, Euglossini) occurs in more than 600 species of Neotropical orchids. Male euglossine bees acquire volatile compounds from both floral and nonfloral sources, which they store in their specialized hind tibiae and later expose during courtship display. Euglossine-pollinated Orchidaceae produce large quantities of floral scent, which serves as both the attractant and reward for male euglossine bees. Upon collecting floral volatiles and aided by the intricate orchid floral morphology, male bees remove and subsequently deposit orchid pollinaria, resulting in pollination. Among euglossine-pollinated Orchidaceae is the species-rich genus Gongora Ruiz & Pav., which provides exceptional opportunities to investigate the evolution of scent-mediated pollinator specialization. Here we review the taxonomy, systematics, and pollination biology of Gongora. We also describe a new physical mechanism of pollination observed for Gongora and discuss the significance of different modes of pollinaria attachment in an evolutionary framework. This work provides the foundation for future research on the evolution of specialized plant–pollinator mutualisms, including elucidating the evolutionary relationships of cryptic species, understanding the evolution of floral adaptations, and investigating the mechanisms of speciation.