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| Author(s): |
Juliana Santos Silva
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2013-07-18 |
| Examining board members: |
Ana Maria Goulart de Azevedo Tozzi;
Jose Rubens Pirani;
Luciano Paganucci de Queiroz;
Gerson Oliveira Romão;
Luiza Sumiko Kinoshita
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| Advisor: | Marcelo Fragomeni Simon; Ana Maria Goulart de Azevedo Tozzi |
| Abstract | |
Mimosa L. is a pantropical genus with more than 500 species, making it the second largest genus of subfamily Mimosoideae. Of the five currently recognized sections of the genus, Mimosa sect. Batocaulon DC. is one of the largest and morphologically most diverse, comprising ca. 190 species. Among the 25 currently recognized series within sect. Batocaulon, Mimosa ser. Leiocarpae Benth. is the largest, comprising 31 species mainly distributed in xeric habitats of South America. It is characterized by the presence of specialized trichomes and by the spikes of tetramerous, diplostemonous flowers. Many of its species are poorly defined, and this was exacerbated by the lack of illustrations for the majority of the species and by the scarcity of collections of some taxa. Molecular phylogenetic studies have supported the monophyly of Mimosa, but they have demonstrated that its infrageneric groups are para- or polyphyletic. The objective of the present work was to conduct a phylogenetic, micromorphologic studies and taxonomic revision of M. ser. Leiocarpae, as a contribution towards its taxonomy and delimitation. The phylogenetic study was based on molecular markers obtained from nuclear (ITS) and chloroplast DNA (matK/trnK, trnD-trnT and trnL-trnF) DNA, analyzed using parsimony and Bayesian methods; the taxonomic and micromorphologic studies were based on traditional methods. In Chapter 1, concerning the phylogeny of M. ser. Leiocarpae, the analyses showed that the group is polyphyletic, and is represented by three distinct lineages. These results demanded a revised circumscription of M. ser. Leiocarpae that recognizes five of the 31 species traditionally included in the group and three more species from Mimosa ser. Bimucronatae Barneby and M. ser. Farinosae Barneby. Chapter 2 is a micromorphological study of the trichome types observed in Mimosa, with emphasis on the species of ser. Leiocarpae, which exhibits notable diversity of trichomes. The leaf trichomes of 35 species were examined using optical and scanning electron microscopes, with the objective of clarifying the traditional terminology for describing these trichome types and for testing hypotheses regarding their evolution. Two basic types of trichomes were recognized, glandular and non-glandular. The glandular trichomes can be sessile or stipitate, while the non-glandular trichomes can be branched (barbate, stellate, lepidote-stellate, lepidote, plumose, and verruciform) or unbranched. Glandular and non-glandular trichomes evolved independently in different lineages of Mimosa, essentially corroborating current hypotheses on trichome evolution by Barneby (1991). Chapter 3 is a palynological study of the species of M. ser. Leiocarpae and of the implications for the taxonomy of the group (Santos-Silva, 2013a). Pollen grains are arranged in tetrads of ditetrads, the latter decussate, isopolar or heteropolar, compressed or not, the outline elliptic or ellipsoid. The results of the pollen morphology do not support the monophyly of M. ser. Leiocarpae s.l., corroborating evidences from molecular phylogenetic studies. Chapter 4 is a revision of M. ser. Leiocarpae s.l.. In this chapter proposed eleven new synonymies, one lectotypification, and one new status. Three species descriptions are emended, and four new geographic records are reported for South America. Annex consist of already published article that describe one new species in Mimosa (Santos-Silva et al. 2013b) (AU) | |