New Acarospora Species Found Across Western U.S.

Kerry Knudsen, Jana Kocourková, Eva Kondrysová, Steve Leavitt, Jason Hollinger, Natassja Noell, Jiří Malíček, and Tim Wheeler published a comprehensive review of the Acarospora group within the order Acarosporales and family Acarosporaceae in North America in MycoKeys volume 142 (pages 73‑102) ¹.net]. Their study details morphological observations and molecular analyses that clarify species boundaries across the continent.

The authors describe a previously unrecorded taxon, Acarospora lactea, collected from Montana, Nevada, and Utah. They also provide fresh descriptions for A. coloradiana, A. nevadensis, and A. utahensis.

They revisit A. peltata, noting that it has been synonymized by Magnusson with the South American species A. strigata; we do not recognize this change, so A. peltata remains recognized as the common North American form while A. strigata is considered relatively rare in South America. The paper further documents A. peltastica, a rare southern California species distinguished by globose ascospores measuring 3.5–4.5 µm in diameter.

Beyond new species, the team publishes an identification key encompassing six members of the A. strigata group found across North America, providing field mycologists with practical tools for distinguishing closely related taxa during surveys or foraging expeditions.

Experts note that this work supplies critical taxonomic clarity on a genus that has long remained understudied despite its ecological ubiquity. By mapping the distribution of A. lactea and refining descriptions of other regional variants, the authors enhance conservation efforts and support accurate identification essential for both scientific research and responsible mushroom foragers who rely on precise taxonomy to avoid misidentification.

The study underscores how detailed morphological and molecular data can reshape our understanding of fungal biodiversity even within well‑known groups. For those interested in North American mycology, these findings offer fresh insights into the ecology of Acarospora species and remind us that many fungal lineages still await comprehensive documentation before their full significance is appreciated in ecosystems and foraging communities alike.