Physaria is a species-rich genus native to the Americas that contains many locally endemic species of conservation concern. Physaria filiformis is a federally threatened annual species occupying glade ecosystems in Arkansas and Missouri. Previous genetic work in P. filiformis based on microsatellites identified a geographically isolated group of populations in the Ouachita Mountains that were strongly genetically divergent from the rest of the species despite apparent morphological similarity. This led to questions about whether the isolated populations were P. filiformis, populations of some other Physaria species, or an unrecognized new species. In this study, we conducted morphometrics and phylogenomic analyses based on 2b-RAD-seq data to understand: 1) which Physaria species is most morphologically similar to the Ouachita populations, 2) whether morphological characteristics distinguish the Ouachita populations from the most morphologically similar Physaria species, 3) the evolutionary relationships of the Ouachita populations with other geographically proximal Physaria and 4) whether phylogenomic data support the distinctiveness of the Ouachita populations. As previously hypothesized, we found that the Ouachita populations were most morphologically similar to P. filiformis. Morphological comparisons between the Ouachita populations and the rest of P. filiformis revealed that the Ouachita populations had smaller flowers, larger fruits, and distinct petal morphology. They also occupy a distinct substrate type and a different physiographic province. Phylogenomic analyses placed the Ouachita populations as sister to the morphologically divergent species P. globosa, with P. filiformis sister to P. globosa + the Ouachita populations. Including the Ouachita populations in P. filiformis would render the group non-monophyletic. This illustrates how the use of an approach combining both morphometrics and genetic data can resolve the taxonomy of a potentially distinct cryptic species, distinguishing it from close relatives. Based on this evidence, we determined that the Ouachita populations represent a distinct species, described here as Physaria ouachitensis . We discuss conservation implications for both P. ouachitensis and P. filiformis.
Abstract— The páramo ecoregion is known for its remarkable biodiversity and evolutionary histories shaped by complex biogeographical processes. To protect and conserve the ecological diversity and evolutionary lineages in this hotspot requires analyzing spatial patterns of phylogenetic diversity and endemism. This study uses spatial phylogenetic methods, combining georeferenced occurrence data with a genus-level phylogeny of the region’s entire vascular flora to investigate the spatial distributions of phylogenetic diversity and endemism. In this study, we assembled a comprehensive dataset of 361 equal-area grid cells covering the páramo biome and compiled occurrence records for 567 vascular plant genera. A phylogeny of vascular plants in the páramo was generated by combining publicly available genetic sequence data with novel genetic data from Colombian herbarium collections. This study examined the vascular plant diversity in the páramo ecosystem and identified distinct centers of neo- and paleoendemism, as well as a strong pattern of phylogenetic clustering across most páramo regions. The phylogenetic beta diversity analysis identified several phylogenetically distinct bioregions, characterized by both widespread, shared evolutionary histories and localized, distinct assemblages. This study provides a scope to prioritize certain areas for protection and to further identify and understand biogeographical patterns in the páramo ecoregion.
Abstract— The genus Hygrophila (Acanthaceae) comprises approximately 100 species with herbaceous habits that are widely distributed in tropical and subtropical regions. Several nomenclatural issues were resolved during this revision of its Brazilian species: lectotypifications for H. conferta , H. helodes , and H. longifolia are designated here, and H. hirsuta is treated as a synonym of H. costata . Our study resulted in the recognition of five species, of which we classify H. paraibana as Endangered (EN), H. costata and H. guianensis as of Least Concern (LC), and H. acutangula and H. nordestina as Data Deficient (DD). We include detailed descriptions of the species, comments on their habitats, reproductive phenologies, geographic distributions, and conservation statuses. Distribution maps, images, and illustrations of the diagnostic characters of each species are also presented.
Abstract— In North America, the tribe Vernonieae (Asteraceae) comprises 92 species distributed mainly in mountain ranges. Combining molecular data for 62 species and herbarium records (N = 5424), spatial phylogenetics was used to identify regions of high phylodiversity, centers of endemism, and patterns of phylogenetic turnover in North America. The study region was divided into 1° latitude and longitude grid cells; four molecular markers (ndhF, trnL, rpl32-trnL, and ITS) were used to construct a phylogram and alpha phylodiversity indices were calculated (phylogenetic diversity and relative phylogenetic diversity) along with categorical analysis of neo- and paleo-endemism (CANAPE). Beta phylodiversity was examined using the PhyloβSimpson and PhyloβRWTurnover indices to determine major phyloregions. A randomization test of phylogenetic diversity revealed phylogenetic clustering in the north and south of North America, while overdispersion was concentrated in the south. Relative phylogenetic diversity showed significant concentrations of long branches in the north and south, whereas central Mexico exhibited concentrations of short branches. The CANAPE analysis revealed centers of paleo-endemism in southeastern Mexico, with long-branching lineages in genera such as Cyrtocymura and Lepidonia . Neo-endemism centers with short-branching species, such as those in genera Eremosis and Vickianthus were also identified, as well as areas with mixed endemism in different regions of Mexico. Phylogenetic turnover patterns determined 16 phyloregions (PhyloβSimpson) and 17 phyloregions (PhyloβRWTurnover).
