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Systematics of Eugenia (Myrtaceae, Myrteae): flower and inflorescence evolution, and taxonomic implications.

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Augusto Giaretta de Oliveira
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Biociências
Defense date:
Examining board members:
Paulo Takeo Sano; Ariane Luna Peixoto; André Olmos Simões; Marcos Eduardo Guerra Sobral
Advisor: Paulo Takeo Sano; Evelyne Jill Lucas

Myrtaceae has about 4600-5800 species distributed in tropical and subtropical areas. Myrteae is one of the most species rich tribe in Myrtaceae with ca. 2500 species. Studies on Myrteae flower development and evolution have shown the homoplastic nature of characters previously considered diagnostic that are now culminating in much-improved taxonomic understanding. The hyper-diverse Eugenia with ca. 1050 species is nested in this tribe, and have been shown as morphologically homogeneous. However, genera previously segregated from Eugenia by the degree of calyx fusion are source of controversy. Molecular phylogeny based on five DNA regions reconstructed fused calyx as evolved several times independently in Eugenia. Morphological assessment of the calyx fusion revealed five development patterns besides the standard condition of the free lobes. Although the development patterns are homoplastic, phylogenetic signal indicates that they can be used in combination to complementary characters to support clades. Membranisepalous pattern is an exception, recovered as exclusive allowing to be used to diagnose an Amazonian clade. Traditionally six-petal species are newly interpreted as petaloid pattern, i.e. four petals are followed by two internal petal-like sepals, and two external fused sepals. Longohypanthium pattern is recognized as an extremely rare condition in Eugenia which hypanthium extends as the stamens whorl resulting in a display of curved stamens in the bud instead the standard straight. Nomenclatural changings and a taxonomic revision of Eugenia sect. Schizocalomyrtus newly circumscribed follow these results. Ten species are detailed described and commented under distribution, conservation, and taxonomy. The inflorescence of Eugenia was also analysed under an integrative approach that revealed arrangements previously ignored as relevant for systematic and taxonomy. Seven patterns were described but five are regarded to an evolutionary assessment. Auxotelic pattern was recovered in the early lineages. It suggests that a hypothetical ancestral is similar to the auxotelic pattern. Fasciculiform pattern is widely found in the most speciose Eugenia sect. Umbellatae, indicating that high rates of diversification may be related to the acquisition of this pattern. This study also provides insights in the evolution of inflorescence arrangement by indicating that flexibility in the racemose branching pattern is likely the innovative key that promoted the diversification of Eugenia in the Neotropics (AU)

FAPESP's process: 14/04043-9 - Phylogeny, biogeography and taxonomic revision of Calycorectes O. Berg (Myrtaceae)
Grantee:Augusto Giaretta de Oliveira
Support type: Scholarships in Brazil - Doctorate