Epidendrum secundum complex as a multidisciplinary approach to specific delimitation

Author(s)

Paula Maldonado Rabelo

• Document type: Master's Dissertation
• Press: Rio Claro. 2016-06-16.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2016-06-10
• Advisor: Alessandra Ike Coan; Fábio Pinheiro

Abstract

The use of various data sources in an integrated manner has facilitated the understanding of interspecific group limits, mainly in the neotropical region whose great biodiversity is related to evolutionary diversification processes. Epidendrum L. is the largest genus of orchids in the Neotropics; E. secundum and E. xanthinum belong to the called "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. Although E. secundum and E. xanthinum present flowers with contrasting colors, they have been considered as belonging to a single one. This work aimed to answer the following questions: 1) Are there floral micromorphological and anatomical differences between samples from different populations of E. secundum and E. xanthinum? 2) Does individuals from E. secundum and E. xanthinum, from distinct populations, display a reciprocal monophyly pattern, with different and exclusive ancestors? 3) Based on different data sources, can individuals from E. secundum and E. xanthinum be considered as distinct species? Therefore, we assessed the floral micromorphology and anatomy of E. secundum and E. xanthinum based on usual light and scanning electron microscopies; molecular analyzes were also performed using the nuclear (ITS region) and chloroplast (clp-psb, ndhJ-tabE) DNA sequences previously tested in Epidendrum. In the present study, we found that most of floral micromorphological and anatomical characters are shared by both E. secundum and E. xanthinum samples from disjoint populations, including individuals of what are previously considered different species. Nevertheless, some differences were found, especially for the labellum of the samples analyzed, mainly for the presence of stomata at different regions, the cell shape in frontal view and the shape of outer periclinal. From 216 floral micromorphological and anatomical characters assessed, only 54 are variable and just five could be used to distinguish individuals at specific level. On the other hand, molecular analysis strongly supports the division of the selected individuals into two monophyletic clades, corroborating the previous division of E. secundum and E. xanthinum as two different species based on colour of the flowers. (AU)

• FAPESP's process: 14/01416-9 - Epidendrum secundum complex as a multidisciplinary approach to specific delimitation
• Grantee: Paula Maldonado Rabelo
• Support Opportunities: Scholarships in Brazil - Master