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Int. J. Plant Sci. 172(7):915–934. 2011. Ó 2011 by The University of Chicago. All rightsreserved. 1058-5893/2011/17207-0008$15.00 DOI: 10.1086/660913
PHYLOGENETICS, MORPHOLOGY, AND EVOLUTION OF THE LARGE GENUS MYRCIA S.L. (MYRTACEAE)
Eve J. Lucas,1 ,*,y Kazue Matsumoto,z Stephen A. Harris,§ Eimear M. Nic Lughadha,* Benedetta Benardini,* and Mark W. Chasey
*Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom; yJodrell Laboratory, Royal Botanic Gardens, ˆKew, Richmond, Surrey TW9 3DS, United Kingdom; zDepartamento de Botanica, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, Campinas, 13083-970 Sao Paulo, Brazil; and §Department of Plant Sciences, ˜ University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom
Phylogenetic relationships of Myrcia s.l., the most species-rich tree genus in the Brazilian cerradoand Atlantic forests, are reconstructed by analysis, with parsimony and Bayesian inference, of four plastid regions (psbA-trnH intergenic spacer, trnL intron, trnL-F intergenic spacer, and matK exon) and the external and internal transcribed spacer regions of nuclear ribosomal DNA. The resulting phylogenetic hypothesis is evaluated in conjunction with key morphological characters and abioticfactors suggested to have inﬂuenced the group’s current distribution. Some lineages identiﬁed by previous classiﬁcations are supported; others with morphological and/or ecological correspondence are recognized for the ﬁrst time. Sequence divergence levels provide good resolution of relationships within but not between the main clades of Myrcia s.l. The previously recognized genera Calyptranthes andGomidesia are shown to be monophyletic, whereas Marlierea is shown not to be; all are nested within paraphyletic Myrcia. A new subgeneric classiﬁcation is required. An interpretation of the origins of Myrcia s.l. and potential causes of speciation in the group is made on the basis of recently published data and accepted geological events. Keywords: biogeography, Brazil, cerrado, Mata Atla ˆntica,South America.
All Neotropical Myrtaceae except the monospeciﬁc genus Tepualia belong to the exclusively ﬂeshy-fruited tribe Myrteae (sensu Wilson et al. 2005). Myrteae can be divided into nine informal groups based on well-supported clades (Lucas et al. 2007). One of these groups, the ‘‘Myrcia group’’ or Myrcia s.l., is deﬁned by its foliaceous cotyledons and soft seed coat,combined with bi- or trilocular ovaries containing two ovules and inﬂorescences usually in panicles. This group equates to the ‘‘principal group’’ referred to by de Candolle (1828) and later published by Berg (1855–1856, 1857–1859) as subtribe Myrcioideae, which was modiﬁed by nomenclatural rules to Myrciinae. The number of genera commonly assigned to Myrcia s.l. has ﬂuctuated over time (table 1),...