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Paleocene occurrence of Pseudotorellia Florin (Ginkgoales) from Northeast Japan and the Meso–Cenozoic history of Pseudotorellia and Torellia

Horiuchi, Junji, Uemura, Kazuhiko
Review of palaeobotany and palynology 2017 v.246 pp. 146-160
Ginkgoales, Mesozoic era, Paleocene epoch, disease diagnosis, leaves, stomatal movement, Japan, Norway
Narrow lanceolate and oblanceolate ginkgoalean leaves collected from the Paleocene Minato Formation, Noda Group, Northeast Japan, are described as Pseudotorellia crista sp. nov. and P. kimurae sp. nov. These leaves are the latest and only Cenozoic record of the genus so far known. Accumulating information shows that some of the characters said to be diagnostic for Torellia Heer emend. Florin and Pseudotorellia Florin respectively are present in both genera which limits the diagnostic value of these characters. The only clear difference between Torellia and Pseudotorellia is the orientation of the stomatal aperture. The two genera are thus considered as being closely allied to each other. Based on the 58 records of Pseudotorellia and Torellia of which cuticles are described, changes in the distribution of these genera from the Rhaetian through to the Paleogene are discussed. Pseudotorellia species from the Paleocene of Japan and Torellia rigida Heer from the Paleogene of Spitsbergen are considered to be specialized forms of the ancestral Mesozoic Pseudotorellia and Torellia due to vicariance and the northward retreat of the genera through time and space.