Epidendrum secundum complex as a multidisciplinary approach to specific delimitation

Abstract

The use of various data sources in an integrated manner has facilitated the understanding of interspecific group limits, mainly in the Neotropical region with its great biodiversity and related evolutionary diversification processes. Epidendrum L. is the largest genus of orchids in the Neotropics; E. secundum and E. xanthinum, belong to the entitled "E. secundum complex" with disjoint distribution in the Espinhaço Range (State of Minas Gerais, Brazil) and Serra do Mar (State of Rio de Janeiro, Brazil). The taxonomic delimitation problems in the complex are due to the large polymorphism as the size and shape of flowers, resulting in discussion about the existence of more than one species. This work aims to answer the following questions: 1) Are there floral micromorphological and anatomical differences between sampled populations of E. secundum and E. xanthinum? 2) Are there different genetic lineages among populations? 3) Based on different data sources, can individuals of these locations be considered as distinct species? Therefore, we will study the floral morphology and anatomy of E. secundum and E. xanthinum from usual light microscopy and scanning electron techniques; molecular analyzes will also be performed using the nuclear DNA sequences (ITS region) and chloroplast (rpl32-trnL) previously tested in Epidendrum. The existence of more than one species will be discussed following the principles of integrative taxonomy. It is believed that the combination and integration of morphology and anatomy to molecular data and reproductive biology may help to clarify these evolutionary aspects and also the relationship between groups of species with taxonomic uncertainties. (AU)