A new species of Pinus (Pinaceae) from the Miocene of Weichang, Hebei Province, China and its evolutionary significance

Abstract

ABSTRACT Pinus (Pinaceae) is the largest genus of the conifers, characterised by needle-leaves usually in fascicles of 2–5 and seed cones with highly specialised and diversified apophyses and umbos. Although a denticulatomucronate umbo is the most common umbo type in the subsection Pinus, genus Pinus, this type has not been well documented in the fossil record of East Asia. Here, we describe exquisitely preserved seed cones and associated needles as Pinus weichangensis sp. nov. from the early Miocene of Weichang County, Hebei Province of China. The new species is characterised by ovoid and symmetrical seed cones with flat to shortly pyramidal apophyses, avallate umbos, and predominantly denticulate and non-geniculate mucros, associated needles in fascicles of two, fascicles persistent, leaf stomata sunken and encircled by Florin rings of type B–C. The character combination of the new species supports the assignment of it to the subsection Pinus, section Pinus, subgenus Pinus, genus Pinus. Detailed comparisons with related extant and fossil species indicate that P. weichangensis has close resemblance with an extant denticulatomucronate species P. thunbergii Parl. Our study suggests that P. thunbergii, native to Japan and South Korea, may have diversified from a continental Asian species such as P. weichangensis.