Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev Phylogeny and biogeography of Astraea with new insights into the evolutionary history of Crotoneae (Euphorbiaceae) Otávio Luis Marques Silva a, ⁎ , Ricarda Riina b,1 , Inês Cordeiro a,1 a Núcleo de Pesquisa Curadoria do Herbário SP, Instituto de Botânica, Avenida Miguel Stéfano 3687, São Paulo 04301-902, SP, Brazil b Real Jardín Botánico, RJB-CSIC, Plaza de Murillo 2, Madrid 28014, Spain ARTICLEINFO Keywords: Croton Crotonoideae Neotropics Brasiliocroton Sagotia Sandwithia ABSTRACT We investigated species relationships in Astraea, a primarily Neotropical genus of tribe Crotoneae centered in Brazil, using data from the nuclear ribosomal ITS, and the plastid trnL-trnF and psbA-trnH spacers. With all species of Astraea sampled, along with representatives from across Crotoneae, the evolutionary history of Astraea was interpreted in a broader framework, as well as divergence time estimates and reconstructions of ancestral areas and morphological character states for Crotoneae. Our results show that Astraea is monophyletic, con- sisting of three main clades, and that most of its diversifcation took place from the Oligocene to the Pliocene, coincident with the formation of the South American “dry diagonal”. As for Crotoneae, our data show incon- gruent phylogenetic positions between the nuclear and chloroplast data for most of its genera, and that the ancestor of the tribe was probably arborescent and might have occupied the Amazon Basin, most likely in moist forest, from which it spread throughout South America in the early Eocene. Ancestral state reconstruction re- covered deeply lobed leaves and staminate petals bearing moniliform trichomes as putative synapomorphies for Astraea, whereas the absence or strong reduction of pistillate petals is widespread in Crotoneae and may be a synapomorphy for the tribe. 1. Introduction Astraea Klotzsch comprises 13 species found throughout the Neotropics, especially in dry environments, with its center of diversity in eastern Brazil and only the three weedy species in the genus reaching the Old Tropics (Gaikwad et al., 2012; Caruzo et al., 2014; Das et al. 2016; Chao et al., 2017; Silva et al., 2019). Diagnostic features of the genus are usually deeply lobed leaves (Fig. 1A–C) with an agglomerate of colleters at the junction of petiole and leaf blade (Fig. 1D), spiciform thyrses (Fig. 1E), staminate fowers with petals bearing moniliform trichomes, and flaments infexed in bud (Fig. 1G), pistillate fowers with slender cylindrical multifd styles (Fig. 1F), and tetrangular or rounded seeds in cross section (Fig. 1I; Webster, 1993; Berry et al. 2005; De-Paula et al. 2011; Riina et al. 2014; Vitarelli et al., 2015; Silva et al., 2019). Previous molecular phylogenetic analyses (Berry et al., 2005; Wurdack et al., 2005; Riina et al., 2014) placed Astraea in tribe Cro- toneae, the most species-rich group of the megadiverse Euphorbiaceae in the Neotropics (Ulloa-Ulloa et al., 2017). In its current delimitation (Webster, 2014), Crotoneae includes fve additional genera: Sagotia Baill., Sandwithia Lanj., Acidocroton Griseb. (including Ophellantha Standl.), Brasiliocroton P.E. Berry & Cordeiro, and the giant genus Croton L., where most of the diversity of the tribe is concentrated (van Ee et al., 2011). According to the current phylogenetic hypothesis, Sagotia and Sandwithia are sister to the rest of the tribe, while the re- maining genera are grouped in two clades, one containing Croton and Brasiliocroton, and the other with Astraea and Acidocroton (Berry et al., 2005; Wurdack et al., 2005; Riina et al., 2014). The phylogenetic and morphological relationships among all Crotoneae genera have not been comprehensively addressed, and the close relationship of Astraea with Acidocroton is surprising, since the latter is unique within Crotoneae by its stipules transformed into spines and leaves that are usually arranged in short internodes (brachiblasts), and also because Acidocroton is found mainly in West Indies, with a few species in Central America and a single one reaching northern South America (Webster, 2014). Among the genera of Crotoneae, Astraea has been represented by just a few species in previous phylogenetic studies (Berry et al., 2005; Wurdack et al., 2005; van Ee et al., 2011; Riina et al., 2014), therefore its monophyly needs further investigation. Moreover, relationships among Astraea species remain unknown, especially after recent https://doi.org/10.1016/j.ympev.2020.106738 Received 31 October 2019; Received in revised form 3 January 2020; Accepted 23 January 2020 ⁎ Corresponding author. E-mail address: otaviolmarques@gmail.com (O.L.M. Silva). 1 Equal contributions. Molecular Phylogenetics and Evolution 145 (2020) 106738 Available online 27 January 2020 1055-7903/ © 2020 Elsevier Inc. All rights reserved. T