Five new species of Acarosporaceae are described from southwestern North America: Acarospora alboparasitica, A. dividens, Sarcogyne alpina, S. basialba, and S. diffusa from Arizona, California, Colorado, Nevada, and Utah. We publish new sequences of A. rouxii, A. subcontigua, A. subcontigua var. invadens and Sarcogyne dakotensis from North America and A. marcii, A. saxonica, and S. oceanica from Europe. Neoacrodontiella is rejected as an eighth genus of Acarosporaceae. Key words: Acarospora similis, calciphytes, Colorado, desert species, Joshua Tree National Park, lichenicolous lichens, Mexico, Nevada, Utah, montane species, red pigmented epihymenial accretions.