Morphometric analysis of the Habenaria parviflora complex (Orchidaceae)

Abstract

We analyzed patterns of morphological differentiation of the Habenaria parviflora complex (Orchidaceae), through morphometric analyses of populations and morphotypes, aiming at evaluating current taxonomic proposals and at identifying discriminative characters for the delimitation of taxa. We performed multivariate and univariate morphometric analyses using 18 morphological characters of 675 individuals from 65 populations distributed throughout Brazil, Argentina and Uruguay, representing 12 morphotypes that comprise nearly all the morphological diversity and geographic distribution of the complex. The group presents morphological patterns difficult to understand which suggest that the complex does not correspond to a single species, nor does each morphotype correspond to a taxon. It was possible to clearly differentiate only two taxa, apart from H. parviflora, by a combination of characters: H. paulensis and H. ulei. Characters associated with flower size, leaf width and opening angle of the sepals were the most discriminatory for both species. The relationships between the populations of the remaining morphotypes exhibited high overlap in the analyses, making it impossible to define morphological groups with the characters used. The number of flowers, ovary length and angles between floral structures, not previously used in the taxonomy of this complex, are important characters for the recognition of taxa and can be further explored by future taxonomic studies of both the group and the genus.