Deviacer pidemarmanii sp. nov. (Polygalaceae) from the Late Eocene–Early Oligocene Badger’s Nose Paleoflora, Modoc County, California

Abstract

Premise of research. Fossils of asymmetrically winged samaras, informally referred to as Acer negundoides MacGinitie (Sapindaceae), from the late Eocene–early Oligocene Badger’s Nose flora (∼34 Ma) of northern California, are described as Deviacer pidemarmanii Myers and Erwin sp. nov. The genus Deviacer Manchester is emended and attributed to the family Polygalaceae. Methodology. The morphological features of more than 40 samaras exquisitely preserved as compressions in lacustrine siltstone of the Badger’s Nose member of the Steamboat Formation were compared to similar extant and fossil-winged fruits. Pivotal results. Deviacer includes compressions of nonschizocarpic asymmetrical samaras with a small dorsal projection. Similar projections characterize the fruits of extant Securidaca (Polygalaceae) and the extinct genus Paleosecuridaca Pigg, Devore, and Wojciechowski, but Acer L. (Sapindaceae) fruits lack these structures. Morphologically, Deviacer is indistinguishable from the anatomically preserved fruits of Paleosecuridaca. Deviacer pidemarmanii sp. nov. is described based on overall fruit size; nutlet shape, size, and orientation to the wing; and wing size, form, and venation. Anatomical features such as locule and seed number in D. pidemarmanii are not preserved, but one specimen appears to be two-seeded, as in Paleosecuridaca. Conclusions. Deviacer is emended and assigned to the Polygalaceae. Paleosecuridaca may be congeneric with Deviacer, but Deviacer fruits are compressions and lack the nutlet anatomy described by Pigg, Devore, and Wojciechowski. Deviacer pidemarmanii records Securidaca-like plants in warm temperate regions of the Pacific Northwest (North America) at least until the latest Eocene–early Oligocene climatic and biotic transition, whereas today extant Securidaca and most other members of the Polygaleae are pantropical. Deviacer pidemarmanii closely resembles the liana Securidaca paniculata Rich. var. lasiocarpa Oort., today a native of northern South America. Recognizing asymmetrically winged samaras from well-dated Cenozoic sediments as related to Securidaca will advance our understanding of the evolutionary relationships and biogeographic history of Polygalaceae and the ecology of Securidaca-like plants in Paleogene vegetation at north temperate latitudes.