Pityostrobus yixianensis sp. nov., a pinaceous cone from the Lower Cretaceous of north-east China

Abstract

A silicified conifer cone was collected from Lower Cretaceous rocks in Yixian, Liaoning Province, north-east China. The cone is long and cylindrical, and its axis contains secondary xylem with resin canals. Vascular traces to the scale and its subtending bract are separate when they diverge from the vascular cylinder of the cone axis. Where the base of the scale is separate from the bract, resin canals are distributed adaxially and abaxially in the vascular traces. Bracts separate from the scales marginally, and the apex of each scale is flattened. Seeds are inverted and occur in pairs on the adaxial surface of fertile scale. Seed is winged and elliptical, lacking both resin cavities and vascular traces in its seed coat. The characters of the Chinese specimen have led to the description of a new species of the fossil genus Pityostrobus as P. yixianensis. When compared with other pinaceous genera, P. yixianensis shows greatest similarity to the extant generaPicea , Pseudotsuga and Larix. It differs from other species of Pityostrobus which have a close relationship with either the genus Pinus or Pseudoaraucaria. The evolutionary and phylogenetic position ofPityostrobus yixianensis is considered to represent an ancestral intermediate between extant conifer genera such asPicea , Pseudotsuga and Larix. Pityostrobus yixianensis represents the first record ofPityostrobus in China and is coeval with the earliest pinaceous cones from Europe and North America.