Leaves of Cercocarpus mixteca n. sp (Rosaceae) from Oligocene sediments, near Tepexi de Rodriguez, Puebla

A new species of Cercocarpus, Cercocarpus mixteca Velasco de Leon & Cevallo s-Ferriz, is described based on leaf impressions from the Los Ahuehuetes lo cality, near Tepexi de Rodriguez, Puebla, Mexico. The lamina is obovate, 1. 3 cm in length by 0.5 cm in width, has a serrate margin in its distal fourt h, craspedodromous venation with a single straight mid-vein and two to four pairs of secondary ones, and areols that tend to be quadrangular in shape. A phenetic analysis of the agglomerative, non-hierarchical type, with mean linkage, is applied using 22 OTUs and 34 character states. The morphologic al characters observed on the leaves of the new fossil plants support the r ecognition of a new taxon closely related to the extant Cercocarpus paucide ntatus growing naturally in northern Mexico. Its microphyll size correspond s with the temperate to xeric climate postulated for the Los Ahuehuetes loc ality; this further suggests that some taxa, like Cercocarpus, have a long history in low latitude North America. In this particular case, the extant Cercocarpus fothergilloides and Cercocarpus macrophyllus could, as they wer e able to colonise new humid and xeric areas, represent descendants of C. m ixteca. (C) 2000 Elsevier Science B.V. All rights reserved.