Phylogenetic analysis and evolution of morphological characters in Metrodorea and related species in Rutoideae (Rutaceae)

Abstract

The aim of the study is to compare distinct morphological characters of Metrodorea (Rutaceae) with those of related genera, under a phylogenetic approach. Morphoanatomy of leaves was analyzed, and data concerning reproductive structures were compiled from the literature. We used available molecular sequences to recover a maximum likelihood tree, and we present a reconstruction of ancestral morphological character states made with the maximum likelihood criterion. The topologies obtained retrieve as synapomorphic characters of Metrodorea: aborted leaflets, vascularized intrapetiolar stipules, sinuous cell walls contour in the surface view of the epidermis, glandular trichomes on the adaxial and proximal region of the petiole, good development of areoles, muricate fruits, and valvate estivation of the corolla. The specific relationships within Metrodorea and between Metrodorea and other genera of Rutoideae are supported by characters as the location of crystals, type of adherence at leaf bases, and presence/absence of trichomes on the blade. The close relationship of Metrodorea and Raulinoa is strongly supported by several synapomorphies. Our data are mostly consistent with recent phylogenies, showing that the monophyly of Esenbeckia cannot be confirmed and that the clade Helietta-Balfourodendron (formerly included in another subfamily) is closely related to Raulinoa and Metrodorea (both part of Pilocarpinae) than to Pilocarpus itself. Possible relationships between these genera are discussed based on the morphological states found, and most of them supporting the hypothesis that Metrodorea is the sister group of Raulinoa.