Garcinia-Like Reproductive Parts from the Early Eocene of India: Systematics, Paleoecology, and Biogeography

Premise of study. Although Garcinia (Garcinieae: Clusiaceae) is well represented through vegetative parts (leaves and wood) in the fossil record, no fossil flower that could provide new information on the reproductive structures of this genus had been discovered until now. Here, for the first time, we report and describe fossil flowers in appreciable numbers with affinity to Garcinia L. from the Early Eocene (ca. 55-52 Ma) of Rajasthan, western India. In addition, we introduce a Garcinia-like fossil flower bud and a fruit from the same stratigraphic level. Methodology. We determine their taxonomic position based on detailed comparative morphology and phylogenetic analysis that resulted from a Bayesian combined analysis of molecular and morphological characters of the modern members of Clusiaceae. Pivotal results. The Eocene flower specimens are characterized by a long pedicellate with a perianth of four preserved petals, a superior and stipitate ovary, and the presence of numerous long staminal filaments arising from the base of the ovary, and a single style is recognized as a new genus and species named Eogarcinia longistaminata A. Ali, R. F. Almeida & M. A. Khan gen. et sp. nov. Conclusions. This finding constitutes the oldest reliably identified reproductive structures of Garcinia from the Cenozoic strata elsewhere. This discovery provides support for the hypothesis of Gondwanan origin and early diversification of Garcinia within the Indian subcontinent during its northward tectonic drift. It also offers new insights into the floral evolutionary trajectory, paleoclimate, and paleobiogeography of Garcinia.