Intercontinental distribution of Plagiochila corrugata (Plagiochilaceae, Hepaticae) inferred from nrDNA ITS sequences and morphology

Plagiochila sect. Vagae is a large pantropical clade that is characterized morphologically by frequent terminal branching, vegetative distribution by propagules on the ventral surface of the leaves and a capsule wall with thickenings in all layers. Plagiochila corrugata from Brazil is characterized by strongly undulate, toothed leaf margins and represents the only known neotropical species of sect. Vagae with unispiral elaters. Plagiochila cambuena from Madagascar is distinguished by the same features. Maximum likelihood and parsimony analyses of 38 nrDNA ITS sequences of Plagiochila reveal P. corrugata and P. cambuena in a weakly (ML) to well (MP) supported monophyletic lineage within R sect. Vagae. As an outcome of the morphological and molecular investigation, P cambuena is relegated to the synonymy of R corrugata. Plagiochila corrugata is placed in a Vagae-subclade with 11 further American species. The range of P. corrugata can be ascribed to long-range dispersal from the Neotropics rather than a Gondwanan distribution. Species from tropical Asia and Africa are placed at the base of the Vagae clade. Branch length within R sect. Vagae points to a sudden radiation. (C) 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146, 469-481.