An Early Malpighiaceous Plant-Pollinator Relationship: Evidence by a Gland-Bearing Petal (Osmophores) from the Eocene of India

Premise of research. Flowering plants have coevolved with their pollinator partners over millions of years, producing a fascinating and interesting diversity of floral tactics and pollinator adaptations. A fossilized malpighiaceous gland-bearing petal recovered from the Gurha lignite mine in Rajasthan, western India, from the early Eocene (~55–52 mya) helps to underscore the evolutionary significance of this angiosperm lineage in the Cenozoic history of India. Methodology. We determine the fossilized gland-bearing petal’s taxonomic position based on detailed macromorphological traits and thoroughly compare them with the modern genera of the tribe Mcvaughieae. Pivotal results. The Eocene specimen is an obovate to orbicular and symmetrical glabrous petal with four short and obovate glandular extensions or osmophores at the limb margin of the basal portion. The specimen is closely similar to the modern gland-bearing petal of the tropical South American genus Mcvaughia W.R. Anderson (Malpighiaceae). Conclusions. As osmophores are oil-producing volatile glands used to signal pollinators (particularly anthophorid bees) the availability of floral resources, we suggest that such specific malpighiaceous plant–anthophorid bee relationships may have existed in the area during the time of deposition (early Eocene).