Didymocyrtis xanthomendozae is reported as new to the USA. Arthonia peltigerina and Pertusaria oculata are reported as new to the contiguous 48 states of the USA. Arthonia clemens, Diplolaeviopsis symmictae and Lichenoconium xanthoriae are reported as new to northwestern North America and Epicladonia simplex as new to the western USA. Three species are reported as new to the Rocky Mountains, and new state records are provided for California, Colorado, Idaho, Oregon and Washington.

Lichen communities in many National Parks are diverse and perform essential but often poorly understood ecological roles. However, lichen diversity in many National Parks is poorly characterized. Because of this, limited interpretive resources are currently available. Here we report a preliminary checklist of the lichen species found in Great Basin National Park, White Pine County, Nevada, USA, including 230 species in 84 genera, identified predominantly from recent field surveys. While our study documents an impressive diversity of lichen species in the Park, we anticipate that a significant percentage of the lichen flora remains to be discovered. Our hope is that this preliminary checklist will provide a foundation for additional lichenological research in Great Basin National Park.

A survey of lichen diversity was conducted at Gitchie Manitou State Preserve in Lyon County, Iowa, using a problem-based learning approach in a course taught at Iowa Lakeside Laboratory during the summer of 2017. Using this approach the students were able to correctly identify about 77%of the collected lichens. Our collections revealed the presence of 34 distinct lichens, representing 23 genera, including the first report of Agonimia optuntiella (Buschardt & Poelt) Vězda for the state of Iowa.

The structure of the peristome of Encalypta procera is represented along with comments on other complex forms in additional supposedly haplolepideous mosses. Relevant applicable literature is mentioned.

Green algal photosynthetic units in the genus Stereocaulon (phyllocladia or areoles) are typically white to pale gray, but certain species develop a darker central portion. Structurally, these dark-centered areoles of crustose Stereocaulon are identical to the phyllocladia of the S. vesuvianum group. The dark-centered photosynthetic units may have an adaptive role, separating tissue for gas exchange from tissue for water uptake and light transmission. I hypothesize that the white portions of cortex on the photosynthetic units have reflective extracellular deposits that optically occlude the cortex but allow gas exchange through hydrophobic air channels. In contrast, the dark centers apparently provide transparent and water-transmissive windows into the algal layer through an otherwise relatively opaque cortex. Cortical windows are apparently unusual in lichens and may be an adaptation to provide gas exchange in cold, wet environments. For crustose species, the areoles often protrude from a thin film of water over rock and the dual cortex appears to provide both light transmission and gas exchange. Similarly, for the S. vesuvianum group, the dual cortex may provide light transmission and gas exchange for water-saturated thalli in oceanic environments.