Cryptantha acrimuricata (Boraginaceae), a distinctive new taxon of series Muricatae

In the process of studying the species <i>Cryptanthamuricata</i> and its varieties, we discovered a unique taxon of the genus that resembles <i>C.muricata</i> but differs in having a mostly densely white-strigose stem vestiture (sometimes with spreading trichomes) and tuberculate to muricate nutlets with often whitish tubercles that are, in comparison with typical <i>C.muricata</i>, larger, with a wider base and more pointed apex, and more densely spaced. We believe this form to be different enough to describe as a new species, <i>Cryptanthaacrimuricata</i>. This new species occurs in southwestern North America: in California and Arizona of the United States and in northern Baja California, Mexico. It occurs in mid- to relatively high elevation mountain regions of mostly desert transition/escarpment in the Transverse and Peninsular Ranges, in the Sonoran and Mohave Deserts, and with some populations scattered in the southern Sierra Nevada. We believe this new species to be closely related to <i>C.clokeyi</i>, <i>C.martirensis</i>, <i>C.muricata</i>, and possibly <i>C.hooveri</i>, of <i>Cryptantha</i> series <i>Muricatae</i>. Detailed molecular phylogenetic are needed to better establish their interrelationships.