Banca de DEFESA: FÚVIO RUBENS OLIVEIRA DA SILVA

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STUDENT : FÚVIO RUBENS OLIVEIRA DA SILVA
DATE: 29/02/2024
TIME: 14:00
LOCAL: Auditório Paulo Cavalcante
TITLE:

Integrative taxonomic revision of neotropical species of Radulaceae (Marchantiophyta)

KEY WORDS:

Tropical America, Radula, Cladoradula, leafy liverworts, taxonomy

PAGES: 344
BIG AREA: Ciências Biológicas
AREA: Botânica
SUMMARY:

Radulaceae Müll. Frib. (Porellales Schljakov; Radulinae R.M.Schust.) is a diverse group with more than 300 species distributed worldwide and one of the most isolated lineages of the leafy liverworts (Marchantiophyta Stotl. & Crand.-Stotl.; Jungermanniidae Engl.). Distinctive morphological features of the family include rhizoids in tufts on the lobule surface, Radula-type branches, large, brown oilbodies, absence of underleaves, and perianth tubular, dorsiventrally flattened. The center of diversity of the species is in the humid tropical regions, although they are distributed on all continents except Antarctica. Most species grow as epiphytes in preserved tropical forests, from the lowlands to montane forests above 4000 m altitude. The family has three genera, but most species belong to the genus Radula Dumort., which is subdivided into five subgenera: Amentuloradula Devos et al., Metaradula R.M.Schust., Odontoradula K.Yamada, Radula e Volutoradula Devos et al. Morphological definitions of these subgenera are problematic and the subgeneric divisions, supported only by molecular data, are unclear, especially among neotropical species. The species of Radulaceae that occur in temperate and paleotropical regions of the world have been reviewed, but there is a gap for the species of the neotropical region, which is one of the main centers of diversity, with more than 140 names described and around 75 species currently accepted. A preliminary revision of the species of Radulaceae in Brazil showed that the number of these currently accepted species is probably excessive and that several of them may be synonyms, although new species may yet be discovered. The aim of this study is to carry out an integrative taxonomic revision of the neotropical species of Radulaceae, based on a comprehensive study of types, additional herbarium collections and field collections, using morphological, anatomical, ecological and palynological evidence. Early on in this study, it was possible to identify new taxa with striking features such as bordered leaves (Chapter I). In addition to the review of species from tropical America, a revision was made of Radulaceae species from tropical Africa, especially Madagascar, which resulted in the discovery of two new synonyms of neotropical species in one African (Chapter II). As part of the taxonomic revision, special attention was paid to little-studied characteristics that can be taxonomically informative, such as spores. In Chapter III, we carried out the first palynological assessment of sixteen species of Radulaceae. Palynological data, especially spore ornamentation, can be an important contribution to the taxonomy of Radulaceae in separating species or groups of species. These groups, however, do not fully correspond to the generic and infrageneric circumscriptions, as supported by molecular evidence. From the totality of the data and the greater understanding in the circumscription of the species, the taxonomy of Radulaceae was revised, in which detailed descriptions of the species, illustrations of selected taxa, identification keys for all species and comments on their relationships, geographical distribution (with maps) and habitat are presented (Chapter IV). The revision recognized 54 species and six varieties, starting from 75 species initially accepted for the Neotropics. Three new species were discovered and are described in this last chapter, as well as three taxa were reinstated as synonyms of other species; a new combination was proposed, as well as 27 new synonyms, 42 new lectotypes, and six species were placed as doubtful or excluded. The taxonomic revision of Radulaceae in tropical America has led to a better understanding of the circumscription and distribution of the taxa, creating a secure base that will help in future studies.

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