Leaf Cuticle Microstructure of Machilus maomingensis sp. nov. (Lauraceae) from the Eocene of the Maoming Basin, South China.

Machilus maomingensis Jin et Tang, sp. nov. from the Eocene Youganwo Formation of the Maoming Basin, South China, is studied in detail from the perspective of the leaf architecture and the excellently preserved cuticle. The leaf margin is entire, the primary venation is pinnate; 6 to 8 secondary veins are present and the major secondary venation is eucamptodromous. Stomata are paracytic and occur on the lower epidermis. Trichome bases are unicellular. Oil cells are present in the upper epidermis. The new fossil species described has features of the Lauraceae, particularly of the extant genus Machilus Rumphius ex Nees, and it is most similar to Machilus chinensis (Bentham) Hemsley, an extant species distributed in southern China and Vietnam. Hence, Machilus maomingensis sp. nov. is inferred to live in a warm and humid climate. The discovery of the present fossil indicates that Machilus has existed in South China from at least the Eocene. [ABSTRACT FROM AUTHOR]