A molecular phylogeny and classification of Verbenaceae.

MARX, HANNAH; O'LEARY NATALY; YUAN, YAOW; LU-IRVING, PATRICIA; TANK, DAVID; MULGURA, MARIA EMA; OLMSTEAD, RICHARD

La Plata

Congreso; IX Reunión Argentina de Cladística y Biogeografía; 2010

Willi Henning Society

Verbenaceae consist of trees, shrubs, lianas, and herbs distributed primarily in Latin America where they occur in a wide array of ecosystems.  Seven chloroplast DNA regions were analysed for 121 samples representing 109 species of Verbenaceae and 18 outgroup species from other families in Lamiales.  The 109 ingroup taxa represent 33 genera, including all but one (Verbenoxylum) genera.  Sampling within genera attempted to reflect generic and tribal diversity in the family, resulting in relatively less sampling of species-rich genera such as Lippia, Lantana, Glandularia, Citharexylum, and Stachytarpheta. Overall this study presents the most extensive phylogenetic study in terms of both taxa and geographic distribution of the Verbenaceae. Three datasets were compiled and analyzed to accommodate the two sampling strategies: 1) all 139 accessions for two regions (ndhF, trnLF), 2) 33 accessions for all seven regions, and 3) all 139 accessions for all seven regions (with missing data scored for the taxa unsampled for the other five regions).  Sequence lengths ranged from 903 nucleotides (nt) in Pitraea cuneato-ovata to 941 nt in Priva lappulacea, and yielded an aligned length of 1232 bp, of which 287 positions were parsimony informative.  This study provides the first phylogeny of Verbenaceae with comprehensive, genus-level sampling.  By including sufficient outgroup sampling, this study confirms the monophyly of Verbenaceae (ML bs = 98%; MP bs = 92%; pp = 1.0; also a unique 6 nt deletion in trnLF). These analyses identify eigth well-supported clades, recognized as tribes (Casselieae, Citharexyleae, Duranteae, Lantaneae, Neospartoneae trib. nov., Petreeae, Priveae, Verbeneae), some of which correspond to tribal level groups in recent classifications, but with many differences relative to those treatments. The main stem of the tree also is moderately to well-supported and resolution is weak or missing only among terminal clades of closely related species (e.g., within tribe Lantaneae and Citharexylum). The small group Petreeae, consisting of Neotropical lianas, is sister to the rest of the family, with Duranteae forming the second branch.  Casselieae and Citharexyleae together form a well-supported clade, which is sister to a large clade comprising Priveae, Neospartoneae trib. nov., Verbeneae, Lantaneae, and the two small genera, Dipyrena and Rhaphithamnus, which remain unplaced in these larger clades. Priveae, Rhaphithamnus, and then Neospartoneae diverge in sequence, leaving a clade comprised of the two most species rich clades, Verbeneae and Lantaneae. One new tribe, Neospartoneae trib. nov., is recognized to accommodate three small genera of Argentine species (Diostea, Neosparton, Lampaya).  A secondary distribution in Verbenaceae occurs mostly in Africa, with a few species in Europe and Asia.  Phylogenetic inference suggests a South American origin for Verbenaceae, with approximately six colonization events giving rise to the Old World species.