Systematics of Vriesea (Bromeliaceae): phylogenetic relationships based on nuclear gene and partial plastome sequences

Vriesea is the second largest genus of the most diverse subfamily of the Bromeliaceae, the Tillandsioideae. Although recent studies focusing on Tillandsioideae have improved the systematics of Vriesea, no consensus has been reached regarding the circumscription of the genus. Here, we present a phylogenetic analysis of the core-Tillandsioideae using the nuclear gene phyC together with plastid data obtained from genome skimming. We investigate evolutionary relationships at the intergeneric level in the Vrieseeae tribe and at the intrageneric level within Vriesea s.s. We sampled a comprehensive dataset, including eleven genera of Tillandsioideae and nearly 50% of all known Vriesea species. We recovered 77,836 bp from the plastid genome that included 92 protein coding genes. Phylogenetic trees were reconstructed using maximum likelihood based on two datasets: 1) the partial plastome alignment; 2) the concatenation of 18 plastid genes and the nuclear gene phyC. Additionally, a bayesian inference was performed on the second dataset. These analyses revealed that Vriesea s.s. forms a well-supported clade encompassing most of the species of the genus. However, our results also identified several remaining issues in the systematics of Vriesea, including a few species nested within the genera Tillandsia and Stigmatodon. Finally, we recognize some putative groups within Vriesea s.s., which we discuss in the light of their morphological and ecological characteristics.