Bauhcis moranii gen. et sp nov (Cercideae, Caesalpinieae), an Oligocene plant from Tepexi de Rodriguez, Puebla, Mex., with leaf architecture similar to Bauhinia and Cercis

The Oligocene Coatzingo Formation (approximate toPie de Vaca Formation), Puebla, Mexico, has yielded a diverse assemblage of plants among which Leguminosae are represented by wood, fruits and leaves or leaflets. Leaf impressions from two specimens have characteristics found in extant members of Cercideae (Caesalpinieae). Morphological observations were corroborated through a phenetic analysis suggesting that morphological differences between the fossil and extant plants correspond to natural variation within the tribe. Although the fossil material closely resembles both Bauhinia and Cercis, its set of characters support the recognition of a new taxon, Bauhcis moranii Calvillo-Canadell and Cevallos-Ferriz. The cladistic analysis further supports that the fossil represents a moment in the history of the tribe, previous to the differentiation of the two extant genera. This new plant adds to the poorly known low-latitude fossil vegetation of Central Mexico and strengthens the idea of a long and complex phytogeography history to explain the extant biodiversity of the area, in which Leguminosae is among the most important component of the flora. (C) 2002 Elsevier Science B.V. All rights reserved.