Molecular Phylogenetics and Trait Evolution in Stigmatodon (Bromeliaceae, Tillandsioideae), an Endemic Genus to Brazilian Rocky Outcrops

Abstract

Abstract The genus Stigmatodon occurs in vertical and bare granite slopes, typical of the inselbergs of the Brazilian Atlantic Forest. Here, we present the first broad phylogenetic analysis focused on Stigmatodon, sampling a total of 83 terminals, including 16 of the 20 species of the genus and the morphologically similar species of Vriesea. We conducted a phylogenetic analysis using two plastid markers (matK and rps16-trnK) and the nuclear gene PHYC to infer phylogenetic relationships and reconstruct ancestral states for ecological and morphological characters. Our results suggest the monophyly of Stigmatodon as originally circumscribed is only possible with the inclusion of morphologically and ecologically similar Vriesea species. In addition, the morphological and anatomical traits led us to propose a new circumscription for the genus, combining eight species of Vriesea to Stigmatodon as S. andaraiensis, S. freicanecanus, S. lancifolius, S. limae, S. oliganthus, S. pseudoliganthus, S. vellozicolus, and S. zonatus. The stomata positioned above the ordinary epidermal cells, the adaxial water-storage parenchyma with axially elongated cells, the stamens positioned in two groups of three on each side of the corolla, and the tubo-laciniate stigma are exclusive to Stigmatodon in its new circumscription. These new morphological and phylogenetic results constitute a relevant contribution to the taxonomy and evolution of Bromeliaceae, one of the most diverse and ecologically important families of flowering plants of the Neotropics.