When Hybrids Are Not Hybrids: A Case Study Of A Putative Hybrid Zone Between Cattleya Coccinea And C. brevipedunculata (orchidaceae)

Cattleya coccinea and C. brevipedunculata (Orchidaceae) are closely related species distinguished primarily by geographical distribution, vegetative morphology and flowering period. Both species inhabit high-elevation regions in south-eastern Brazil, but are traditionally associated with different habitats, located in cloudy forests and campos rupestres (rocky fields), respectively. We used morphometrics and genetic variation of microsatellite markers to test the occurrence of a hybrid zone between these species located in Parque Estadual do Ibitipoca (PEI), Brazil. Morphological data reveal a continuum of variation between the putative taxa, influenced mainly by characters of leaf, pseudobulb and peduncle. However, genetic data do not support the occurrence of hybridization and introgression in PEI, showing that it is a pure population of C. brevipedunculata. Differences in vegetative characters among individuals from cloudy forests and campos rupestres suggest that morphological variation may be related to phenotypic plasticity in response to environmental light fluctuations, an unknown situation for this species. These results highlight the inconsistency of morphology for the identification of hybrids and the role of vegetative characters as a possible complicating factor for the taxonomy of these species, as they are subject to environmental influence. © 2016 The Linnean Society of London181462163