Upper Cretaceous Araucarian Cones from Hokkaido and Saghalien: Araucaria nipponensis Sp. Nov.

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  • Six ovulate, permineralized cones, four cone-scale complexes, and one isolated seed are described from the Upper Cretaceous Upper Yezo and Miho Groups from Hokkaido, Japan, and Saghalien, Russia. Cones are spherical, 3.5-6.0 cm in diameter, with prominent thick bracts. Thick ovuliferous scales are almost completely united with the bracts and are not readily distinguishable on all scales. Cone-scale tissues consist of prominent abaxial and adaxial sclerenchyma bands with a central zone of thin-walled cells filled with dark contents that are often missing in abraded cones. Cone-scale vasculature is located in the thin-walled cells of this central zone. There is one large ovule per cone-scale complex with a thick sclerotesta showing a zigzag sclereid pattern. The nucellus is free from the integument except at the chalaza and shows a prominent wavy apex. Megagametophytes and embryos with two cotyledons are poorly preserved but are present in a few seeds. The presence of pollen tubes in the nucellar tissues of a fossil araucarian is demonstrated for the first time in these cones. Cones can be distinguished from those of Araucaria nihongii by a larger overall size at maturity, the structure of the cone-scale and its tissue composition, the lack of a bract abscission layer, and a thicker ovuliferous scale without a prominent \"ligular sulcus.\" These cones show similarities to the South American section Araucaria (= Columbea) species and are known to have shed their scales at maturity.

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    Copyright 1994 by The University of Chicago
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    • Stockey, R.A., Nishida, H., and Nishida, M. (1994). Upper Cretaceous Araucarian Cones from Hokkaido and Saghalien: Araucaria nipponensis Sp. Nov. International Journal of Plant Sciences , Vol. 155, No. 6, 806-815