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

Abstract

Tribe 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.

Nutlet micromorphology of the genus Marrubium L. and allies and its systematic implication (Lamiaceae: tribe Marrubieae)

“…Marrubieae Vis., with five genera and ca. 91 species, is one of the 10 Lamioideae tribes distributed mainly in southern Europe and North Africa (Siadati et al, 2018). They are mostly nonaromatic herbs or subshrubs with campanulate to rotate calyx and often with secondary calyx lobes, zygomorphic and 2-lipped corolla and stamens included or shortly exerted from the corolla (Siadati et al, 2018;Harley et al, 2004).…”

“…Spach and Moluccella L., the second one comprising species of Ballota L., the third clade containing Pseudodictamnus Fabr. and related species and the fourth one including Marrubium L. species (Siadati et al, 2018). Acanthoprasium, with two species, is a European genus with a woody habit, spiny bracteoles and upper lip of corolla totally hairy.…”

“…According to Bendiksby et al (2011), the annual or short-lived perennials Moluccella, contains eight species in southwestern Asia and the Mediterranean regions, are characterized by a zygomorphic calyx more or less expanded at the mouth, internally glabrous, and usually lobed with both primary and secondary indentations. The genus Ballota are subshrubs to perennial herbs with herbaceous bracteoles and shortly exerted stamens from the corolla and extend from Macaronesia, Europe to Mediterranean and Western Asia (Siadati et al, 2018). According to Bentham (1832Bentham ( -1836, the genus Ballota had traditionally been divided into three sections based on two main morphological characters, woody against herbaceous habit and the type of bracteoles (spinose against herbaceous): (1) sect.…”

“…Beringeria (Neck.) Benth., which is recently raised to generic rank by Siadati et al (2018) and (3) sect. Ballota Benth.…”

“…Moreover, members of sect. Beringeria recently raised to generic rank as Pseudodictamnus, which accommodates perennial herbs with herbaceous bracteoles, expanded calyx limb with 6-20 teeth and widely distributed from Eurasia to North Africa (Siadati et al, 2018). The genus Marrubium with about 50 species have usually toothed and petiolate leaves, 5-15 (-30) lobed calyx covered by dense stellate trichomes, corolla tube shorter than calyx and stamens included in the corolla tube (Harley et al, 2004).…”