LAUSR

PREMISE Passiflora is a diverse genus of about 570 extant species primarily distributed in the Americas, from the eastern United States to Argentina and Chile. Nevertheless, the known fossil record of Passiflora is small. To date, only two fossil seed species have been unequivocally assigned to the genus. In this contribution, rare sulcate seeds from Gray Fossil Site are described as a third fossil seed species of Passiflora. METHODS Three partial seeds with sulcate sculpture from Gray Fossil Site, early Pliocene, Tennessee, U.S.A., were examined, photographed, and measured. They were compared to samples of sulcate seeds from six extant Passiflora species in supersection Decaloba. A broader survey of sulcate seeds produced by modern species in the subgenera Decaloba, Deidamioides, and Tryphostemmatoides was done using published illustrations and descriptions. RESULTS The Gray Fossil Site seeds are described as Passiflora sulcatasperma, sp. nov., and assigned to subgenus Decaloba, supersection Decaloba. They are characterized by their small size, elliptical shape, ridged-and-sulcate sculpture, rugulose ridges, and thin palisade seed coat. CONCLUSIONS The two largest subgenera of Passiflora can be identified from Neogene fossils. Subgenus Decaloba is represented by two fossil seed species, Passiflora bulgarica (Miocene, Bulgaria) and Passiflora sulcatasperma (Pliocene, U.S.A.). Subgenus Passiflora is represented by fossil pollen (Miocene, Argentina and Brazil) and Passiflora appalachiana seeds (Pliocene, U.S.A.). The distributions of fossil and modern species suggest that Passiflora may have used both North Atlantic and Antarctic routes to expand into Europe and the Asian-Oceanian paleotropics, respectively. This article is protected by copyright. All rights reserved.