Comparative floral structure and evolution in Galipeinae (Galipeeae: Rutaceae) and its implications at different systematic levels

Abstract

Galipeinae (Rutoideae) is the most species-rich subtribe of Rutaceae in the Neotropics. The taxonomy of Galipeinae is complex as molecular phylogenies demonstrate that rearrangements of genera are necessary to reach the monophyly of the subtribe. A few detailed studies have found variability in floral features, such as different patterns of organ fusion and symmetry, with potential systematic importance. However, this was shown for a limited number of taxa. This study aimed to provide a broader comparative account of the floral structure of Galipeinae and closely related taxa of Rutoideae. Some floral features, such as the cochlear aestivation of petals and a free zone of carpels, support the monophyly of Galipeinae without Adiscanthus. Other features, such as apocarpy, anacrostyly, antitropous ovules and zig-zag micropyles, also provide support for the affinity of Rutaceae in Sapindales. Furthermore, complex patterns of organ synorganization of Galipeinae are more diverse than previously shown, and are probably correlated to other features that are not found elsewhere in Sapindales. Finally, we identified homoplastic features that are also widespread in asterids, probably related to similar floral functions, such as variable patterns of monosymmetric tubular corollas, two fertile adaxial stamens with basal appendages of variable length and herkogamy.