Pollination of endangered Philodendron cipoense (Araceae): floral scent ensures the attraction of several specialized cyclocephaline beetle species (Melolonthidae, Cyclocephalini)

The remarkable species richness of the Neotropical aroid genus Philodendron (Araceae) is closely linked to its specialized nocturnal pollination system, where chemically distinct floral scents selectively attract night-active cyclocephaline beetles (Melolonthidae, Cyclocephalini). This study explores the floral biology and chemical ecology of Philodendron cipoense, an endangered, rupicolous species endemic to Brazil’s Espinhaço mountain range in the Campo Rupestre. Through qualitative and quantitative analyses of floral scent chemistry and field experiments, we assessed the role of key volatile organic compounds (VOCs) in pollinator attraction. P. cipoense relies heavily on pollinators and attracted a diverse assemblage of specialized beetles, including Cyclocephala atricapilla, C. variolosa, Chalepides dilatatus, and Erioscelis sp. Its floral scent is dominated by (Z)-jasmone, 4-vinylanisole, and isojasmol, collectively accounting for 97% of total emissions. Field experiments confirmed the attractiveness of (Z)-jasmone, successfully luring a male of C. atricapilla (pollinator) and C. celata (non-pollinator) individuals of both sexes. These findings underscore the pivotal role of floral scent as an olfactory cue in pollinator attraction, revealing asymmetrical mutualisms and interdependence between P. cipoense and its pollinators. Our results provide valuable insights for conservation strategies and targeted action plans to protect this threatened species.