- North America, with over 400 species of Astragalus (Fabaceae), is one of three major centers of diversity, all of which comprise the majority of the nearly 1750 species of Astragalus worldwide. One of the most diverse species, Astragalus lentiginosus of Section Diphysi, is a polymorphic complex of over 40 varieties, ranging from the West Coast to Texas and the Rocky Mountains. Palantia was a sectional name within the genus Tium used by Rydberg for taxa formerly reduced by Jones to varieties of A. lentiginosus. They share cylindrical pods that, unlike the rest of A. lentiginosus, do not become bladdery inflated upon maturity. The Palantia, in a modern interpretation, consists of A. mokiacensis and A. bryantii plus the other scarcely inflated varieties of A. lentiginosus, primarily A. lentiginosus var. maricopae, A. lentiginosus var. palans, A. lentiginosus var. ursinus, and A. lentiginosus var. wilsonii. Every major revision has delimited these taxa differently. A principal coordinates analysis of morphological data from herbarium specimens was used to determine the affinities between type specimens and extant populations of these taxa and to determine the degree of morphological similarity among these taxa. For the genetic analysis, highly polymorphic cpDNA microsatellites were selected due to their applicability to both genetic and phylogenetic questions across a wide range of taxonomic levels. Based on the results of the chloroplast haplotype and morphological datasets, the species, A. mokiacensis, A. bryantii, A. iodanthus and A. pseudiodanthus, are recognized as varieties of A. lentiginosus. The taxon recently recognized as A. lentiginosus var. trumbullensis is morphologically similar to the lectotype of Astragalus mokiacensis. Astragalus lentiginosus var. trumbullensis is herein recognized as a low-elevation minor variant and considered a synonym of A. lentiginosus var. mokiacensis. A taxonomic key and complete synonymy are included.
- Key words: Astragalus, Fabaceae, Edward Palmer, nomenclature, microsatellite, chloroplast, principal coordinates analysis, Utah, Arizona, Nevada