Genetic realignment and synopsis of subtribe Castillejinae (Scrophulariaceae: tribe Pediculareae)

The taxonomy of subtribe Castillejinae, comprising approximately 250 hemiparasitic species principally of western North and South America, is re-evaluated on the generic and subgeneric levels. Based on studies of chromosome number, seed and seed coat morphology, intergeneric hybridizations, and floral morphology, six genera are recognized. The circumscription of three genera remains the same: Clevelandia (one species); Cordylanthus (18 species); Ophiocephaltus (one species). The species of Orthocarpus, a highly heterogeneous and probably polyphyletic genus as constituted, are distributed to three genera: 1) Orthocarpus (with affinities to Cordylanthus) is restricted to the type section and subgenus; 2) sects. Castillejoides and Cordylanthoides of subg. Orthocarpus (closely allied to the Castilleja pilosa group) are placed in Castilleja; 3) subg. Triphysaria is raised to generic status. The genus Gentrya is given subgeneric status in Castilleja. The large and expanded genus Castilleja is subdivided into three subgenera: Colacus (with three sections); Gentrya; and Castilleja, which includes the majority of species in the genus. A phylogenetic chart depicts our view of evolutionary relationships within the subtribe. Keys to genera of subtribe Castillejinae and keys to subgenera and sections (excluding sections of subg. Castilleja) of genus Castilleja are provided. New combinations are proposed in Castilleja (two subgenera: Colacus and Gentrya, one section: Oncorhynchus, 11 species and 8 subspecies: C. ambigua subspp. humboldtiensis and insalutata, C. attenuata, C. brevistyla, C. campestris and subsp. succulenta, C. densiflora and subspp. gracilis and obispoensis, C. exserta and subspp. latifolia and venusta, C. lacera, C. lasiorhyncha, C. lineariloba, C. rubicundula and subsp. lithospermoides, C. tenuis, C. racemosa) and in Triphysaria (four species and two subspecies: T. eriantha and subsp. rosea, T. floribunda, T. micrantha, T. pusilla, T. versicolor subsp. faucibarbata)