Loxopteroides weeksae gen. et sp. nov. (Anacardiaceae) samaras and associated foliage from the Eocene of western North America

An extinct kind of winged fruit found at several Eocene sites in California and Oregon, western USA, occurs in association with pinnately compound anacardiaceous leaves that have been called Rhus mixta. The samaras were previously treated along with isolated leaves from the Chalk Bluffs flora of California in an extinct sapindaceous genus, Thouiniopsis myricaefolia (Lesquereux) MacGinitie. However, the samaras are nonschizocarpic and hence readily distinguished from the mericarps of extant Sapindaceae such as Acer, Thouinia and Thouinidium. We reassign the fruits to Anacardiaceae and note similarity to the extant Neotropical genus Loxopterygium which differs, however, in the shape of the endocarp and placement of the style. Fruits of Loxopteroides weeksae gen. et sp. nov. co-occur with leaves of Rhus mixta at multiple localities in California and Oregon.