Sapindaceous Affinities of the Pteleaecarpum Fruits from the Tertiary of Eurasia and North America

Abstract

Fruit remains of the extinct genus Pteleaecarpum Weyland from the Tertiary of Europe, Asia, and North America are interpreted as detached valves of readily dehiscing tricarpellate, three-winged capsules. These characters in combination with loculicidal dehiscence, reticulate venation joining into marginal veins on the valves, hypogynous flowers, axial serial placentation, and fasciculate trichomes indicate close affinities to the tribes Harpullieae and Koelreuterieae of the Sapindaceae. Two allopatric species are recognized, P. bronnii (Unger) Weyland (Eurasia) and P. oregonense (Arnold) Manchester comb. nov. (North America), which differ in fruit size and length of terminal projections. Pteleaecarpum first appears in the Eocene of Asia and western North America and is present by the Eocene-Oligocene in Arctic regions (Spitzbergen, Kamchatka). The genus extends from the Oligocene to Pliocene of Europe, Eocene to Oligocene of Kazakhstan, Upper Eocene to Upper Miocene of eastern Asia and Upper Eocene to Lower Oligocene of western North America. The Eocene appearance and spread of Pteleaecarpum across the Northern Hemisphere coincides in timing with that of other sapindalean genera with winged fruits such as Koelreuteria and Acer.