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 Teritary of Europe, Asia, and North America are interpreted as detached valves of readily dehiscing tricarpellate, three-winger 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. [Koelreuteria oregonensis] (North America), which differ in fruit size and length of terminal projections. Ptelecarpum 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 appearance and spread of Pteleaecarpum across the Northern Hemisphere coincidences in timing with that of other sapindalean genera with winged fruits such as Koelreuteria and Acer.