Bryum calobryoides, a New Species from Western North America

Abstract

Bryum calobryoides is described as new based on collections from British Columbia, Alberta, Washington, Idaho, Montana, Colorado, and California. Some herbarium specimens were determined as B. capitellatum C. Muell. & Kindb., which is a form of B. capillare. Affinities of the new species are unclear. Distinctive features include small size, julaceous stems, broadly ovate to suborbicular, concave leaves, obtuse to acute leaf apex, with or without an apiculus, and costa usually to midleaf or percurrent. Sporophytes are unknown. The species is found on acidic to basic rock and soil at montane to alpine elevations. During field studies in the alpine zone of the Olympic Mountains in Washington State, I collect- ed a distinctive sterile Bryum from a basalt outcrop. Nothing in the collections at UBc, in Andrews (1940), Lawton (1971), or floras from elsewhere in the world matched it, so I put it aside for future study. During subsequent work on the genus in western North America, I discovered several herbarium specimens similar to the Olympic Mountain gathering, includ- ing one from Montana labeled B. capitellatum C. Muell. & Kindb. This species was placed into syn- onymy under B. gemmiparum by Andrews (1940). This decision was followed by Lawton (1971). The type specimen, at CANM, proved upon careful study to be an unusual form of B. capillare. The habitat, Borders of ditches at Comox, Vancouver Island (Macoun & Kindberg 1892), although typical for B. capillare, differs conspicuously from that of the Montana and Olympic Mountain collections. These collections are sufficiently different from both B. capillare and B. gemmiparum, as well as all other Bryum species from North America, to be consid- ered a distinct species. Since the type of B. capitel- latum is a form of B. capillare, it must be placed into synonymy under the latter. In this study I pro- vide a name for the new species, note possible re- lationships with other species, and provide habitat and distributional data.