Abstract—Stellaria (Caryophyllaceae, tribe Alsineae) is a cosmopolitan genus of herbaceous plants that heretofore has lacked a stable estimate of total number of species. Here, we attempted to sample all species currently recognized under the name Stellaria to determine which belong to a core Stellaria genus versus which are masquerading under this name and are instead more closely related to one of several outgroup lineages. Phylogenetic relationships inferred with RAD loci were recovered with generally high levels of support, regardless of age of specimens (here up to 98 yr) utilized for molecular work. Analyses resolved a monophyletic, core radiation of Stellaria that is sister to Cerastium and others. Within core Stellaria, of which we sampled ca. 87% of species, we recovered five primary lineages. However, current infrageneric hypotheses are incongruous with phylogenomic data, and most morphology-based infrageneric hypotheses break down in light of these results. Outside of core Stellaria we recovered numerous other species currently ascribed to Stellaria that are in need of revised generic placement. Based on current results, however, we propose several new taxonomic and nomenclatural renovations within core Stellaria and external to this group as contribution towards stabilization of generic boundaries in Alsineae. These modifications include description of a new genus of Caryophyllaceae from eastern Asia, Nubelaria, as well description of a new genus, Rabelera, to accommodate the lineage previously and more widely known as Stellaria holostea. Nine new combinations are proposed in the genera Adenonema, Cerastium, Mesostemma, Nubelaria, Rabelera, and core Stellaria. Additionally, one new status, one new synonymy, and lectotypes for four species are proposed. We estimate core Stellaria to consist of approximately 112 species, a decrease from many other published species counts. Our results lay a robust foundation for future evolutionary, phylogenetic, and morphological comparisons within Stellaria and among relatives.
Whereas the eastern North American-eastern Asian floristic connection represents one of the most widely studied biogeographical relationships in flowering plant evolution, connections between western North America and Asia have been comparatively rarely investigated, especially through genetic approaches. Stellaria irrigua is one of several plants that has been treated as an exceptionally dramatic example of a disjunction between floristically similar, high alpine biotas of the southern Rocky Mountains and south-central Siberia. We here employ numerous new field collections and ddRADseq data to test the hypothesis that S. irrigua-a species that has been known for over 180 years-represents a long-distance disjunction between the southern Rocky Mountains and central Asia. Extensive fieldwork, review and perusal of herbarium materials, and phylogenomic analyses indicate that S. irrigua is broadly distributed across an amphi-Beringian arc extending from southern and central Asia, east through Beringia, and south throughout mountainous regions of western North America. Sampled Asian populations formed two clades, and North American individuals all formed a clade embedded within this broader Asian lineage. Stellaria irrigua is, however, rendered non-monophyletic by a lineage that is embedded within the North American populations and is ecologically and morphologically distinctive from S. irrigua. The identity of this newly recognized lineage, which was in prior works attributed to S. irrigua, has been confused since plants of the former were first collected in the San Juan Mountains of Colorado in the late 1800s under Arenaria and Alsine. We provide a new name for this taxon, Stellaria sanjuanensis, a charismatic starwort of dry alpine scree slopes of the southern Rocky Mountains. Additionally, two lectotypes are designated, one holotype and one isotype are identified, and two new synonymies are proposed, to help stabilize the taxonomy and nomenclature of this long-confused species complex. A key to the starworts of the southern Rocky Mountains is also provided, and Stellaria alsine is reported as new to the region.
Abstract—Recent phylogenetic analysis circumscribes the bounds of a core genus of Stellaria comprising five major extant clades and around 112 species. Some finer scale phylogenetic relationships emerging from that study are interpreted here. The Larbreae and Petiolares clades are the main foci, as they comprise the bulk of Stellaria diversity. In particular, I address the implications of our phylogenetic work on some widespread and morphologically complex lineages of starworts, including the Stellaria borealis, Stellaria cuspidata, Stellaria longipes, and Stellaria media groups, and also briefly discuss other subclades within the Larbreae and Petiolares clades. Based on phylogenetic evidence, Stellaria sitchana is here recognized as a distinct species from Stellaria borealis rather than as Stellaria borealis subsp. sitchana, and this lineage is furthermore reported from the southern hemisphere for the first time. Other newly discovered lineages that require revised nomenclatural concepts pending future work also are briefly treated. Overall, a picture of widespread evolutionary parallelism emerges within Stellaria, and this parallelism is largely responsible for the non-monophyletic nature of most previous subdivisions of the genus.
Across angiosperms, evolutionary loss of petals has been rampant and characterizes many distantly related lineages (e.g., in the
Abstract—Despite being dominant elements of understory communities in the coniferous forests of western North America, phylogenetic relationships among bilberries (Vaccinium section Myrtillus) remain unresolved. Morphological delimitation among most western bilberry species is tenuous, and traditionally employed molecular sources of phylogenetic information have yielded insufficient variability. Moreover, these species are hypothesized to have undergone extensive introgression. We used RADseq data analyzed with maximum likelihood species tree estimation and Patterson’s D-statistic analyses to examine the influence of introgression on relationships among Vaccinium myrtillus, V. scoparium, and V. cespitosum. Additionally, we used these data to assess whether the populations of V. myrtillus disjunct between North America and Eurasia are monophyletic and should continue to be recognized as conspecific. Significant genome-wide introgression, as determined through D-statistic analyses, was detected between North American samples of V. myrtillus and V. cespitosum, and to a lesser extent, between V. myrtillus and V. scoparium. No significant D-values were detected between V. scoparium and V. cespitosum. Accessions of Vaccinium myrtillus from Eurasia and North America were recovered as non-monophyletic, prompting our proposed resurrection of V. oreophilum for North American material. The long-assumed sister species relationship between V. oreophilum and V. scoparium was not recovered in our analysis. Instead, V. oreophilum and V. cespitosum were inferred to be sister taxa. This study reveals considerable introgression detectable in the evolutionary history of western North American bilberries and demonstrates the utility of RADseq data to resolve species level relationships in groups that undergo reticulate evolution such as Vaccinium.
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