The monotypic brazilian genus Diacrodon is a synonym of Borreria (Spermacoceae, Rubiaceae) : morphological and molecular evidences

• Autores: Miguel, Laila Mabel; Sobrado, Sandra Virginia; Janssens, Steven; Dessein, Steven; Cabral, Elsa Leonor
• Año de publicación: 2018
• Idioma: español castellano
• Tipo de recurso: artículo
• Fuente: Anais da Academia Brasileira de Ciencias, 2018, vol. 90, no. 2, p. 1397-1415.
• Materia: Flower; Fruit; ITS-ETS dataset; Morphology; Pollen; Seed
• Institución: Universidad Nacional del Nordeste

Fil: Miguel, Laila Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina.
Fil: Miguel, Laila Mabel. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina.
Fil: Sobrado, Sandra Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina.
Fil: Sobrado, Sandra Virginia. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina.
Fil: Janssens, Steven. Jardín Botánico Meise; Bélgica.
Fil: Dessein, Steven. Jardín Botánico Meise; Bélgica.
Fil: Cabral, Elsa Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina.
Fil: Cabral, Elsa Leonor. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina.
Diacrodon is a monotypic genus of the tribe Spermacoceae (Rubiaceae), endemic to northeastern Brazil. Diacrodon compressus is frequently misidentified with a two lobed calyx species of Borreria, B. verticillata. Traditionally, in Spermacoceae the fruit type was considered a diagnostic character among the genera. In this sense, D. compressus presents a strongly compressed, one seeded and indehiscent fruit (vs. globose, two seeded and dehiscent fruit in B. verticillata). In this work, we address two objectives: evaluate the systematic position and determine the identity of Diacrodon in respect to other taxa. Molecular analyses using ITS and ETS indicate that D. compressus is strongly related to other species of Borreria. The morphological results revealed that D. compressus, despite of its type of fruit, is identical to Borreria in floral and palynological features. As conclusion, the new combination Borreria diacrodonta is made and a lectotype is designated. An updated description of the species and a key to the Borreria species with a two lobed calyx are provided. The distribution of B. diacrodonta is extended to Brazilian states Goiás and Minas Gerais, and Paraguay. By this taxonomical change it has become clear that the dehiscence of the fruits lack taxonomic value in the delimitation of Borreria.