Phylogeny and revised classification of New World Ruellia

Abstract

With 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.

A synopsis of Ruellia (Acanthaceae) in Angola, including two species new to science

“…Different pollen types are rare elsewhere in Ruellia although are notable in the sect. Blechum (P.Browne) E.Tripp & T.F.Daniel of the New World, where species have 3-syncolporate pollen grains (i.e., the apertures meet at the poles), often and with a finely to coarsely reticulate exine (Tripp et al, 2009;Manzitto-Tripp & Daniel, 2023), and so differing from the typical 3-(or 5-)porate spherical grains with coarse exine in Ruellia. Ruellia togoensis would otherwise fit well within sect.…”

“…Ruellia L. (Acanthaceae: Acanthoideae: Ruellieae: Ruelliinae) is the third most species-rich genus in the Acanthaceae, with c. 350 species globally (Tripp et al, 2013;Manzitto-Tripp et al, 2022;Manzitto-Tripp & Daniel, 2023). Although it extends into warm temperate regions, diversity in Ruellia is concentrated in the tropics with by far the most species in the neotropics (Tripp & Darbyshire, 2017;Manzitto-Tripp & Daniel, 2023).…”

“…Ruellia L. (Acanthaceae: Acanthoideae: Ruellieae: Ruelliinae) is the third most species-rich genus in the Acanthaceae, with c. 350 species globally (Tripp et al, 2013;Manzitto-Tripp et al, 2022;Manzitto-Tripp & Daniel, 2023). Although it extends into warm temperate regions, diversity in Ruellia is concentrated in the tropics with by far the most species in the neotropics (Tripp & Darbyshire, 2017;Manzitto-Tripp & Daniel, 2023). However, the palaeotropical taxa of the genus, whilst much less species-rich (Tripp & Darbyshire, 2017), comprise the earliest diverging lineages within the genus and so are critical for understanding its evolutionary and biogeographic history (Tripp, 2007;Tripp et al, 2013).…”

Can heterosis and inbreeding depression explain the maintenance of outcrossing in a cleistogamous perennial?

“…Ruellia humilis Nutt (Acanthaceae) is a short-lived herbaceous perennial native to prairies and sandy soils throughout the midwestern United States (Fernald, 1945). It is part of Section Boreosilva, a clade that includes the five species native to eastern North America (Manzitto-Tripp and Daniel, 2023). All species in this clade are cleistogamous, with individual plants producing both CH and CL flowers.…”

Notes on the identity and typification of Ruellia malabarica (Acanthaceae), a species reported as narrow endemic to the Malabar region of Kerala, India

“…Ruellia Plum. ex L. (Acanthaceae: Acanthoideae) is distributed chiefly in the tropical and subtropical regions to North America with c. 375 species globally (Manzitto-Tripp & Daniel, 2023). The genus is represented in India by 11 species (Arisdason et al, 2020), of which four species, including two species recognised under Dipteracanthus Nees, are recorded in Kerala (Nayar et al, 2006).…”