Floral structure in Galipeinae (Rutaceae) and its implications in the evolution, systematics and biology of the group

Author(s)

Juliana Hanna Leite El Ottra

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2014-12-03

Examining board members

Jose Rubens Pirani; Maria do Carmo Estanislau do Amaral; Diego Demarco; Elza Maria Guimaraes Santos

• Advisor: Jose Rubens Pirani; Emerson Ricardo Pansarin

Abstract

Galipeinae (Galipeeae, Rutoideae) is the most diversified subtribe of Rutaceae in the Neotropical region. Recent molecular phylogenies support the monophyly of the group. Even though the circumscription of taxa in the subtribe is based mainly on floral traits, there are few detailed studies on the floral structure of the group, preventing an accurate use of floral features in systematic and evolutionary studies. Furthermore, the functional implications of the floral features to the biology of the species in the group still need support from ecological studies, since these are scarce. In this context, we analyzed comparatively the floral structure of several genera of Galipeinae and closely related american genera, presenting detailed descriptions and discussing the relevance of the findings to the systematics and evolution of the group. Additionally we investigated the functional implications of some floral features on an ecological approach, through floral biology and pollination studies of three species of the group (Almeidea rubra, Conchocarpus macrophyllus e Angostura bracteata), as well as based on literature data and field observations on other species. Here we found that floral features strongly support the Galipeinae clade without Adiscanthus, such as cochlear aestivation of petals (either ascending or oblique), filaments dorsiventrally flattened, and a short basal syncarpous zone of carpels, with usually less than half-length of the ovary. The close relationship of Adiscanthus and Hortia, indicated by current molecular phylogenies, is supported by structural features, such as the postgenital connection of petals formed through the interlocking of short epidermal cells and cuticle projections only in bud stage; anthers with the vascular bundle forked towards its apex and base; and petal tips inwardly bent in the centre of the bud. Floral features further support other phylogenetic relationships recently found at the generic or infrageneric levels. Regarding the functional role of floral features, the synorganization of organs of different floral whorls shows several patterns among the studied species, and the resulting floral architecture seems to influence on the nectar access to pollinators. These ecological issues are discussed at the familiar level, notably their relation to long-tongued and/or long-beaked nectarivorous pollinators, such as lepidopterans and birds. Also, we found evidence that herkogamy is a widespread feature in Galipeinae, and the functional role of the androecium monosymmetry is now reported for some species. Finally, floral features indicate in some species floral specialization toward the main groups of pollinators found (lepidopterans), such as nectar volume and concentration, floral tube features, scent and delicate landing platforms. In this study we have also identified a series of hypotheses to be explored in future integrative studies with floral structure, biology, pollination and evolution in Rutaceae (AU)

• FAPESP's process: 09/08764-4 - Floral evolution and systematics of Galipeinae (Rutaceae)
• Grantee: Juliana Hanna Leite El Ottra
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)