Marcelo Fernando Devecchi

Simaba arenaria (Simaroubaceae): A New Species from Sandy Coastal Plains in Northeastern Brazil, with Notes on Seedling Morphology

Abstract In this paper we describe and illustrate a new species of Simaba from the sandy coastal plains in northeastern Brazil, and discuss the controversial limits of the three sections proposed in the genus by Englerian classification. Simaba arenaria has a restricted distribution: it is known only from two small, somewhat disturbed areas, in restinga vegetation of Bahia and Sergipe states. The evaluation of its threatened status indicates that it is an endangered taxon, according to the IUCN Red List categories and criteria. We also provide novel data on the seedling of this species.

Flora das cangas da Serra dos Carajás, Pará, Brasil: Picramniaceae

Two species of Picramniaceae are found in Serra dos Carajas, Para, Brazil, both belonging to the genus Picramnia: P. ferrea and P. latifolia. Only the former one was recorded in the areas of cangas, being a species endemic to the cangas. This taxonomic study presents a morphological description, detailed illustrations and diagnostic comments of P. ferrea.

Testing the monophyly of Simaba (Simaroubaceae): Evidence from five molecular regions and morphology

Generic circumscriptions in the mostly pantropical family Simaroubaceae are somewhat controversial. Simaba is the largest genus, currently defined as exclusively neotropical, with around 25 species of trees and shrubs, but both its limits and infrageneric classification have been a matter of discussion and divergence. Traditionally, species of the genus have been treated in three sections: Simaba sect. Tenuiflorae, S. sect. Floribundae and S. sect. Grandiflorae, but a phylogenetic analysis suggested that the latter two may not be monophyletic. To test the monophyly of Simaba and its infrageneric classification, we used a molecular approach based on DNA sequence data from two nuclear ribosomal spacer regions (ITS and ETS) and three plastid regions (rps16 intron, and intergenic spacers psbA-trnH and trnL-trnF), including a comprehensive sampling of species from Simaba and closely related genera. We also performed ancestral character reconstructions to identify morphological characters that could serve as synapomorphies for major clades and to explore patterns of homoplasy in the morphological dataset. Our results show Simaba as traditionally circumscribed is not monophyletic, with taxa segregated into two strongly supported but distinct clades, one of which is more closely related to Simarouba. The three main clades that emerged in the phylogeny include a mostly Amazonian Simaba clade (which includes the type species of Simaba and the remaining species of S. sect. Tenuiflorae, here proposed to be recognized as Simaba sensu stricto), a mostly extra-Amazonian Simaba clade (a distinct lineage that will be recognized as Homalolepis, a genus currently treated in synonymy and equivalent to Simaba sections Grandiflorae and Floribundae), and the Simarouba clade (including all of its current species). These three clades are characterized by a combination of morphological characters, described in detail herein, some of which are novel features for Simaba not previously reported in the literature. Mapping character-states on the phylogenetic tree provides tests for evolutionary hypotheses. For example, our reconstruction of habit and geographic distribution suggests that the diversification of several shrubby species within the extra-Amazonian lineage in the South American cerrados probably occurred from ancestors inhabiting tropical forests, involving transitions in morphological and ecological traits.