A preliminary phylogeny of Zapoteca (Fabaceae: Caesalpinioideae: Mimosoid clade)

The legume genus Zapoteca is separated from the genus Calliandra, i.e., by having pollen arranged in 16-grained polyads (compared to 8-grained polyads in Calliandra) and in chromosome number (13 vs. 8 or 11). As currently circumscribed, Zapoteca contains 22 species and 13 subspecies placed in five subgenera. This study included 20 species and 11 subspecies representing all subgenera. Representative species from the closely related genera Calliandra, Havardia, Pithecellobium and Viguieranthus were also included, as the more distantly related species Senegalia senegal and Vachellia farnesiana. The aims of this study were to test the monophyly of Zapoteca and investigate phylogenetic relationships within the genus. Total DNA was extracted from leaf material and the nuclear ETS and ITS, and plastid trnL-trnF regions were amplified. Additional sequence data were downloaded from GenBank, and the data sets were analyzed using Bayesian inference. Results show that Zapoteca is monophyletic and that the monospecific subgenera (subg. Nervosa and subg. Aculeata) are resolved as separate lineages within the genus, subg. Nervosa (containing Z. nervosa) as sister to all remaining taxa of Zapoteca. Subgenera containing more than one species (subg. Amazonica, subg. Zapoteca and subg. Ravenia) are shown to be non-monophyletic. Two subspecies of Z. caracasana, subsp. caracasana and subsp. weberbaueri, are found together in a clade. Furthermore, Zapoteca tehuana and Z. portoricensis subsp. portoricensis, Z. formosa subsp. gracilis and Z. formosa subsp. schottii are shown to be monophyletic. However, the other subspecific taxa of Z. formosa and of Z. portoricensis are not supported as monophyletic