Polyphyly of the genus Micromeria (Lamiaceae) - evidence from cpDNA sequence data

Publication Type:Journal Article
Year of Publication:2005
Authors:C. Brauchler, Meimberg, H., Abele, T., Heubl, G.
Date Published:Jan
Keywords:Clinopodium, Dna-Sequences, Genera, Labiatae, Lamiaceae, Micromeria, Molecular phylogeny, Polyphyly, Trnk, trnL-F

Micromeria Benth. (Lamiaceae, Nepetoideac) is a very common genus in the Mediterranean region. To test the monophyly of the genus and to elucidate its phylogenetic placement within subtribe Menthinae (Dumort) Endl, of tribe Mentheae Dumort we performed parsimony analysis of trnK intron sequence data of 51 accessions representing 15 genera of Nepetoideae and two genera of subfamily Ajugoideae. Tree topology reveals a well-supported "core group" indicating four distinct lineages. The first one comprises three species of Satureja L. s.str., the second one includes taxa of the genus Clinopodium L. from both the Old and the New World, paraphyletic with respect to Monarda L. and two species of Micromeria section Pseudomelissa Benth. A third group contains all samples of the remaining Micromeria species. Within this monophyly, a western lineage including taxa, from NW Africa, the Balearic, and the Canary Islands, is sister to an eastern lineage with species distributed from SE Asia to the western Mediterranean. In a further clade the genera Thymbra L., Thymus L., and Origanum L. are grouped together. Combined analysis using a reduced dataset of trnK/trnL-F sequences increased support for the infrageneric resolution within Micromeria. Based on the phylogenetic reconstructions there is evidence that the genus as currently circumscribed is polyphyletic. Results are discussed in the context of morphology, karyology, and biogeography, outlining the necessity of removing section Pseudomelissa from Micromeria.

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