Central Brazilian Cerrado is regarded as the center of origin and dispersion of Hypenia (Lamiaceae: subtribe Hyptidineae) in South America. The genus has either remained undivided or been divided into two or seven taxonomic sections, based almost exclusively on a limited range of floral features. Interspecific chemical delimitation to complement analyses of botanical traits is described. Multivariate analysis of essential oils of ten species in the vegetative stage supports the taxonomic division in two sections. Cluster I included four species belonging to section Laxiflorae in addition to H. irregularis, which were characterized by the highest percentages of spathulenol and caryophyllene oxide. Cluster II contained five species belonging to section Densiflorae with α-cadinol, α-muurolene and a-muurolol as major constituents. Cadinanes and germacranes/ aromadendranes seem to be chemotaxonomic markers of sections Densiflorae and Laxiflorae, respectively. Furthermore, redundancy analysis revealed no significant correlation between edaphic factors and oil chemovariations, suggesting that Hypenia oils consist of constitutive rather than induced compounds.
Hypenia; essential oil; chemical variability; chemotaxonomy; multivariate analysis
