Systematics and biogeography of the genus Teucrium (Lamiaceae)

Abstract

Teucrium L. is the second-largest genus of subfamily Ajugoideae with a subcosmopolitan distribution and 434 taxa (Govaerts RA, Paton A, Harvey Y, Navarro T, Del Rosario Garcia Pena M, World checklist of Lamiaceae. The Board of Trustees of the Royal Botanic Gardens Kew, Kew. www.kew.org/wcsp/, 2013). The Mediterranean region and surrounding floristic areas are the main center of diversity with around 90% of the total Teucrium species in the world. We describe the systematic of Teucrium following Bentham (Labiatarum genera et species. Ridgeway Sons, London, 1833), Boissier (Flora Orientalis IV. H. Georg, Geneva/ Basel, 1879) and Kästner (Übersicht zur systematischen gliederung der gattung Teucrium L. Biocosme Mésogéen 6:63-78, 1989) with the recognition of the independent status of the section Montana Lazaro Ibiza (Navarro, Teucrium L. In: Castroviejo S et al (eds) Flora Iberica, VerbenaceaeLabiataeCallitrichaceae, vol 7. Real Jardín Botánico, CSIC, Madrid, pp 30-166, 2010). 341 herbarium specimens of 97 Teucrium taxa from throughout the world were studied, three taxa of its phy-logenetic related genera Spartothamnella Briq., Oncinocalyx F. Muell., and Teucridium F. Hook, and two taxa of its segregated genera Rubiteucris Kudô and Leucosceptrum Smith. Based on the species biogeographical distribution and the main discriminant systematic characters, almost five major biogeographic and taxo-nomic species groups can differentiate. The group of species with 2-lipped corolla and zygomorphic calyx (sections Pycnobotrys Benth., Stachyobotrys Benth., Scorodonia (Hill) Schreb. and Teucriopsis Benth.) which provide a clear example of the Eurasian pattern of radiation from C Asia and China. The group of species with 1-lipped corolla and subactinomorphic calyx (sections Polium (Mill.) Schreb., Chamaedrys (Mill.) Schreb., Montana Lazaro Ibiza, Isotriodon Boiss., Scordium (Mill.) Schreb., and subsection Pumila), which represent the Mediterranean pattern of radiation, with a high degree of recent diversification. The typical Mediterranean species with 1-lipped corolla and actinomorphic calyx, consistent with the bulk of species of section Teucrium (Kästner, Übersicht zur systematischen gliederung der gattung Teucrium L. Biocosme Mésogéen 6:63-78, 1989). The Australian and S America 1-lipped corolla species with actinomorphic calyx, (Teucrium subsection Crética (pro part)) (Kästner, Übersicht zur systematischen gliederung der gattung Teucrium L. Biocosme Mésogéen 6:63-78, 1989). Finally, the species with unclear 1-lipped corolla and actinomorphic calyx (Australian and Cape Region species belong to section Teucrium). The section Teucrium is the most heterogeneous and distinctive group within Teucrium with three different geographical distribution in Australian, N America and Mexico Teucrium while as other Ajugoideae genera closed to Teucrium such as Schnabelia Hand.-Mazz. All the sections occurs in the Mediterranean area, NW Africa, N Sahara Desert (Morocco, Algeria, Tunisia and Libya), N Egypt to the Ethiopia mountains, SW Arabian mountains, the Sinai Peninsula and through the arid regions up through W Asia and Europe. Section Teucriopsis is exclusive of Canary and Madeira islands, section Pycnobotrys distributed only in SE Asia and section Leucosceptrum Smith., exclusive from India.