Phylogeny and revised classification of New World Ruellia

Abstract

AbstractWith ca. 375 species worldwide, Ruellia is a morphologically diverse and geographically widespread lineage of flowering plants. The majority of these species (ca. 275 of 375) occur in the New World (NW), with most of these occurring in the tropics and only about 65 occurring in temperate regions. In the NW, the genus spans some 77° of latitude, ranging from the northern United States (Wisconsin) to northeastern Argentina (Córdoba) and southern Uruguay (Canelones). In this study, we generated ddRAD molecular sequence data for 187 of 275 species of NW Ruellia (ca. 68% of NW species) to reconstruct phylogenetic relationships within this lineage. Coupled with morphological and ecological information, we used this well‐resolved and strongly supported molecular phylogeny to delimit 15 sections of NW Ruellia. Representing the first comprehensive attempt in ca. 125 years, we present a revised classification for NW Ruellia, which places a total of 205 species in the following sections: Ruellia sect. Aphragmia, sect. Blechum, sect. Boreosilva, sect. Brasilia, sect. Cerradicola, sect. Chiropterophilae, sect. Chromatoruellia, sect. Eurychanes, sect. Gymnacanthus, sect. Mexicanae, sect. Physiruellia, sect. Ruellia, sect. Siphonacanthus, sect. Stephanophysum, and sect. Strobiliformes. Nomenclatural innovations in this study include the description of several new sections, new combinations, and new names proposed. Our study complements an earlier reclassification of Old World species to provide a globally unique perspective on the taxonomy and phylogeny of a geographically widespread lineage of flowering plants.