Morphological variability of Poa resinulosa species complex (Poaceae) and relationships with sect. Dioicopoa species

Abstract

The Poa resinulosa complex includes a group of disjunct but morphologically similar species: P. calchaquiensis, P. pedersenii, and P. resinulosa. To evaluate and analyze the species of the Poa resinulosa complex and related species, we measured 40 morphological and anatomical characters in specimens of Poa calchaquiensis, P. lanigera, P. pilcomayensis, and P. resinulosa. This data set was analysed together with a previous matrix of  Poa section Dioicopoa (Giussani, 2000), also including  P. nubensis, a new species similar to P. calchaquiensis. By means of the principal components analysis and statistical tests, the species of the P. resinulosa complex were circumscribed. Poa resinulosa is described as a new variety of P. ligularis, distinguished by its shorter ligule, shorter leaves and culms, broader blades and minor stomata. A key for the identification of Poa ligularis var. resinulosa and related taxa is presented together with a map representing the geographical distribution of both varieties of P. ligularis