A new fossil species of Cryptomeria (Cupressaceae) from the Rupelian of the Lühe Basin, Yunnan, East Asia: Implications for palaeobiogeography and palaeoecology

Cryptomeria (Cupressaceae) is a relic genus that was widely distributed throughout Eurasia during the Cenozoic. Interpretation of the biogeographic history of this genus is currently limited by lack of fossil records from the Paleogene of East Asia. Here, we report on a new fossil species of Cryptomeria, Cryptomeria yunnanensis W.N. Ding et Z.K. Zhou sp. nov., based on well-preserved compressions and impressions from the Rupelian (~ 32 Ma) of the Lühe Basin, Yunnan, Southwest China. Sterile shoots are assigned to Cryptomeria based on gross-morphological and cuticular (morphological) characters and are compared with extant and fossils species described so far. The shoots exhibit spirally arranged sessile subulate leaves, leaf cuticles show densely arranged and irregularly oriented monocyclic stomata, which are characteristic for the genus. Contemporary and historical distributions of Cryptomeria suggest that a decrease of precipitation in former distribution areas in East Asia may have been crucial in shaping the present relic distribution pattern of this ancient conifer.