Three New Species of Trapeliopsis on Soil in Western North America

Abstract

Two squamulose species and one crustose species ofTrapeliopsis are described from the western United States based on morphological, anatomical, and ITS sequence data. The newly described species pair, T. californica and T. steppica, consistently differs from T. wallrothii in morphology, ascospores, secondary products, and ITS sequence. Previous reports of Trapeliopsis wallrothii from North America should be referred toT. californica. Morphologically similar to Trapeliopsis californica, T. steppica is separated from that species by the presence of dark granular soredia in discrete roundish soralia; a thinner, duller cortex; and slightly smaller and more appressed squamules.Trapeliopsis steppica is apparently endemic to western North America, pre- dominantly in the intermountain region.Trapeliopsis californica, an esorediate frequently fertile species, predominates in California and west of the Cascade crest in the Pacific Northwest. The third new species, T. bisorediata, is a rarely collected, but locally common in the semi-arid inter- mountain region of the Pacific Northwest. It is characterized by soredia of two types on a whitish pruinose crustose-areolate non-lobate thallus. Between the major mountain ranges of western North America lie expansive semiarid basins and plateaus. Although most of the lichen flora of this area is broadly distributed in the northern hemi- sphere, ecological and floristic studies in this area have revealed a number of North American lichens endemic to the region often called the ''intermoun- tain West.'' Some of these were discovered early on (e.g., Rhizoplaca haydenii(Tuck.) W. A. Weber), some recently rediscovered (e.g., Physconia isidi- igera (Zahlbr. in Herre) Essl.) while others have been described only recently (e.g., Aspicilia filifor- mis Rosentreter, Heteroplacidium congestum (Breuss & McCune) Breuss, Xanthoparmelia ida- hoensis Hale). Ecological and floristic studies of biotic crusts in semi-arid areas revealed three more undescribed species. Over a decade has elapsed since these were noticed by Roger Rosentreter, Bruce Ryan, and the authors. Two of them were illustrated and keyed in McCune and Goward (1995, p. 166) as Trapeliop- sis sp. and T. wallrothii. We sought to clarify the taxonomic status of these specimens, but the mor- phology did not provide clear answers. Use of mo- lecular tools has finally allowed us to proceed with confidence. This paper summarizes our findings on