In the Caribbean region, the Melastomataceae are represented by about 450 species (from 28 genera), close to 400 of them endemic. The majority of these endemic species (approximately 330) belong to the tribe Miconieae, a monophyletic group characterized by flowers with inferior or partly inferior ovaries that develop into baccate fruits, stamens with no or only poorly developed connective appendages, and the absence of megastyloids and imbricate bracts at the base of the flowers. A phylogenetic analysis of 460 accessions from 450 species of the tribe Miconieae, including 139 present in the Antilles (103 of these endemic), was performed based on nuclear (nrITS) and plastid (ndhF) DNA sequence data. This analysis shows that most of the Caribbean endemics are the product of five radiation events: (1) a clade containing the Caribbean endemic (or near-endemic) genera Pachyanthus, Calycogonium, Tetrazygia and Charianthus, as well as a few representatives of Miconia and Leandra.(2) The genus Mecranium.(3) The Caribbean species of Miconia section Chaenopleura (which are probably not the sister group of Andean Chaenopleura). (4) The Greater Antillean species of Clidemia and Ossaea (including Sagraea). (5) The Lesser Antillean representatives of Clidemia. Caribbean endemics that are more closely related to mainland species, rather than other Caribbean species are rare, and these often are segregates of widespread continental species. Because of a lack of resolution at the base of several clades, it is currently not possible to determine which mainland groups are the closest relatives of these Caribbean endemics, thus preventing us from establishing unequivocally the geographical origins of these species.Resumen En la región del Caribe la familia Melastomataceae está representada por cerca de 450 especies (de 28°géneros), 400 de ellas endémicas. La mayoría de estas especies (approximately 330) pertenecen a la tribu Miconieae, un grupo monofilético caracterizado por flores con ovario parcial o totalmente ínfero que se desarrollan en frutos bayados, estambres con apéndices ausentes o poco desarrollados, ausencia de mega estiloides, y la ausencia de brácteas imbricadas en la base del as flores. Se realizó un análisis filogenético basado en secuencias nucleares (nrITS) de cloroplasto (ndhF) para la tribu Miconieae. El análisis incluyó 460 individuos, representando 450 especies de la tribu, de las cuales 139 están presentes en el Caribe (103 de estas endémicas). El análisis muestra que la mayoría de las especies endémicas del Caribe son producto de cinco eventos de radiación: (1) Un clado que contiene los géneros endémicos (o casi endémicos) Pachyanthus, Calycogonium, Tetrazygia y Charianthus, así como representantes de Miconia y Leandra. (2) El género Mecranium. (3) las especies Antillanas de Miconia sección Chaenopleura. (4) Las especies de las Antillas mayores de Clidemia y Ossaea (incluyendo Sagraea). (5) Las especies de las Antillas menores de Clidemia. Especies endémicas del Caribe que son hermanas o que están cercanamente...

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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.Resumen 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 monofilético como tradicionalmente se ha definido. Sin embargo es posible distinguir un grupo, Pachyanthus s.s., que se caracteriza por poseer pétalos ovados a obovados, conspicuamente unguiculados, lóbulos del cáliz fusionados antes de la antesis, pero que se separan en segmentos a manera de sépalos, anteras ovadas a oblongas, rectas, amarillas, sin apéndices en el conectivo o, si presentes, inconspicuos, dehiscencia de las anteras por un poro apical pequeño, y numerosas semillas de solo 1-2 mm de longitud, obpiramidales, con una testa lisa. Las restantes esp...

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