Ex uno, multis: taxonomic revision in Navarretia divaricata (Polemoniaceae) and the recognition of four additional cryptic or near-cryptic species

Abstract. Navarretia divaricata, endemic to western North America and most recently considered a single species with two subspecies, was re-examined in light of field work, DNA sequences, comparative morphology, and a review of herbarium specimens including types. From these studies, we lectotypify the material on which N. divaricata is based, elevate N. divaricata subsp. vividior, which is an allotetraploid, to species rank (as N. vividior comb. et stat. nov.), and recognize three additional species: N. modocensis sp. nov., N. aeroides sp. nov., and N. torreyella sp. nov. Navarretia modocensis, the diploid paternal progenitor of N. vividior, is morphologically cryptic with respect to its allotetraploid offspring and difficult to distinguish on herbarium sheets. Navarretia aeroides, the diploid maternal progenitor of N. vividior, is nearly cryptic, but more easily distinguished from both N. modocensis and N. vividior by its smaller, more glandular inflorescences. Navarretia torreyella is readily distinguished from all of these species, but has been generally mistaken for N. divaricata subsp. vividior given its colored corolla tube and rare co-occurrence with the other vividior-like species. Conservation assessments, an identification key, and table of comparative morphological features are provided for each species, emended descriptions for N. divaricata and N. vividior, and a discussion of the syntypes for Gilia divaricata Torr. ex A.Gray.