Morphological and DNA analyses suggest the reinstatement of four synonymized Cecropia species

Abstract

The genus Cecropia contains 61 species of high ecological importance in the Neotropics. Cecropia pachystachya Trecul has a wide geographic distribution and high morphological variability. The last taxonomic review of C. pachystachya was performed in 2005 and incorporated seven other Cecropia species by synonymization. However, this synonymization was not fully accepted by experts in Urticaceae because of high morphological variations in the taxon. In this study, we aimed to evaluate whether the morphological variations observed in C. pachystachya morphotypes also occurred at the DNA level and to contribute to the understanding of the evolutionary relationship between species morphotypes. Morphological analysis of eight species descriptors in 28 accessions of C. pachystachya allowed the differentiation of all five morphotypes evaluated. The analysis of the trnL-trnF (plastid) and ITS (nuclear) regions from 24 accessions by maximum parsimony, maximum likelihood, and Bayesian inference methods showed a robust molecular differentiation between C. pachystachya morphotypes. Climate was the main factor that seemed to influence clade formation in the phylogenetic trees. The higher genetic relation among morphotypes from the Amazon, Caatinga, and Cerrado regions corroborated previous hypotheses of close relationships between these biomes in past ages. The morphotype group from the Atlantic Forest seemed to be related to the proposed Pleistocene refuges to this biome. The overall analysis of morphological and molecular data shows robust differences between C. pachystachya synonymized morphotypes, which indicates the need of a taxonomic revision of the C. pachystachya complex and subsequent reinstatement of at least four synonymized species.