Early Oligocene Itea (Iteaceae) leaves from East Asia and their biogeographic implications

Compressed materials of fossil foliage described here as Itea polyneura sp. nov. (Iteaceae) were collected from the Oligocene of Wenshan, Yunnan Province, southwestern China. The identification is based on the following characters: eucamptodromous secondary veins, strict scalariform tertiary veins, irregular tooth with setaceous apex. The leaf morphology of all modern and fossil species was compared with the new species from Wenshan and show that I. polyneura is most similar to the extant East Asian species Itea omeiensis, which inhabits subtropical forests of southern China. This discovery represents the first unambiguous leaf fossil record of Itea in East Asia. Together with other species in the Wenshan flora and evidence from several other flora in southern China, these findings demonstrate that Itea from East Asia arose with the Paleogene modernization.