NEW SPECIES OF TAPIRIRA (ANACARDIACEAE) FROM EARLY MIOCENE SEDIMENTS OF THE EL CIEN FORMATION, BAJA CALIFORNIA SUR, MEXICO

Abstract

From the early Miocene El Cien Formation, Baja California Sur, Mexico, a new Tapirira species is described. Among the diagnostic features that relate T. peninsularis Martínez-Cabrera & Cevallos-Ferriz sp. nov. with extant species of the genus are libriform septate fibers, radial canals with 2–4 layers of epithelial cells, and scanty paratracheal to vasicentric axial parenchyma. In order to establish similarity between wood of T. peninsularis and fossil and extant species of the genus, cluster and principal component analyses were carried out. Numerical analyses support that Tapirira peninsularis is distinct from other extant and fossil species of the genus. Quantitative characters like frequency of radial canals, diameter of fibres, vessel element lumen, and height and width of the rays with radial canals are important in distinguishing between these taxa. Though these wood characters are quantitative, they also have been useful in the recognition of two subgenera within the genus. Recognition of this new species, along with the fossil record of the group, and a phytogeographic analysis suggest a low latitude North American origin for the genus, and a subsequent introduction to southern latitudes.