Untangling the generic boundaries in tribe Marrubieae (Lamiaceae: Lamioideae) using nuclear and plastid DNA sequences

Abstract

AbstractTribe Marrubieae (Lamiaceae: Lamioideae) comprises about 91 species classified in four genera distributed from Europe to West and Central Asia and North Africa. Here, we present a phylogenetic analysis of cpDNA (rpl32–trnL, rps16, trnL intron, trnL–trnF spacer) and nuclear ribosomal (ITS) sequence data of 68 accessions representing all genera and most sections of Marrubieae. Our taxon sampling covers is dense for the genera Ballota and Marrubium, including a total of 60 of 85 currently recognized taxa (species and subspecies). Parsimony and Bayesian analyses of individual nrITS and cpDNA markers, as well as the combined plastid dataset, produced largely congruent trees. Our results confirm the monophyly of tribe Marrubieae. All analyses retrieved four well supported clades in the tribe. The phylogenetic position of the genera Acanthoprasium and Moluccella is consistent with previous studies and both are recovered as monophyletic. The most important result of the present study is the splitting of the genus Ballota, in its traditional concept, into two well–supported clades matching well with the genera Ballota and Pseudodictamnus. Moreover, Marrubium, in its current circumscription, is paraphyletic, but will become monophyletic by transferring Ballota deserti to this genus. In conclusion, we propose the recognition of five genera in tribe Marrubieae: Acanthoprasium, Ballota, Moluccella, Marrubium and the resurrected segregate Pseudodictamnus. The required new combinations are proposed.