Preliminary Molecular Phylogenetic Studies in Pachyanthus (Miconieae, Melastomataceae)

• Published in: The Botanical review 2008-05, Vol.74 (1), p.37-52
• Main Authors: Bécquer-Granados, Eldis R, Neubig, Kurt M, Judd, Walter S, Michelangeli, Fabian A, Abbott, J. Richard, Penneys, Darin S
• Format: Article
• Language: English
• Subjects: Anthers; Biological taxonomies; Biomedical and Life Sciences; Botany; Calyx; Evolution; Flowering; flowers; Flowers & plants; fruits (plant anatomy); Genera; genes; Genetics; indigenous species; Inflorescences; internal transcribed spacers; Life Sciences; literature reviews; Melastomataceae; molecular sequence data; molecular systematics; Natural history; Ovaries; Pachyanthus; Petals; Phylogenetics; phylogeny; Phylogeny (Botany); Plant Anatomy/Development; Plant Ecology; plant morphology; Plant phylogeny; Plant Physiology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; plant taxonomy; ribosomal DNA; Rosidae; shrubs; Taxa; wild plants
• ISSN: 0006-8101; 1874-9372
• DOI: 10.1007/s12229-008-9010-z

Pachyanthus (Melastomataceae: Miconieae) is traditionally circumscribed as a group of 20 species of Caribbean shrubs, mostly local Cuban endemics. However, the exact number of species is unknown because generic delimitations are still unclear for most genera of Miconieae. To test the monophyly of Pachyanthus, we produced a molecular phylogeny using nrITS and plastid trnS-G sequence data for 38 taxa of Miconieae in the genera Pachyanthus, Calycogonium, Tetrazygia, and Miconia. A species of Graffenrieda, a member of the sister group, Merianieae, was used as an outgroup. In the single-gene and combined analyses Pachyanthus is never recovered as a monophyletic group in any of its traditional circumscriptions. However, it is possible to distinguish a clade, Pachyanthus s.s., which is characterized by ovate to obovate petals that are conspicuously unguiculate; calyx lobes connate before anthesis, that separate into sepal-like segments; straight, ovate to oblong, yellow anthers without connective appendages or, if present, then inconspicuous, anthers dehiscing by small apical pores, and fruits with numerous seeds, 1-2 mm long, obpyramidal, with a smooth testa. The remaining species traditionally included in Pachyanthus do not have any of these features. They do not form a single monophyletic group, but instead are scattered across several clades, which also contain species of Calycogonium, Miconia, and Tetrazygia. Additional detailed molecular and morphological studies are needed in the Miconieae to ascertain whether these clades should be treated as new genera or recircumscribed as part of currently recognized genera in the Caribbean region, such as Calycogonium and Tetrazygia. /// Pachyanthus (Melastomataceae: Miconieae) ha sido reconocido tradicionalmente como un grupo de unas 20 especies de arbustos caribeños, mayormente endémicos locales de Cuba. Sin embargo, el número exacto de especies es aun desconocido porque las delimitaciones genéricas de la mayoría de los géneros en Miconieae son aun dudosas. Para probar la monofilia de Pachyanthus, se realizó un análisis filogenético molecular con las secuencias de nrITS y de trnS-G del cloroplasto de 38 taxones de Miconieae pertenecientes a los géneros Pachyanthus, Calycogonium, Tetrazygia y Miconia. Como grupo externo se utilizó una especie de Graffenrieda, perteneciente a la tribu hermana Merianeae. En ninguno de los análisis de cada gen por separado, o en el análisis combinado se resuelve Pachyanthus como grupo m