Eight new species are described from the Chihuahuan Desert in southern New Mexico: Acarospora agostiniana, A. divisa, A. fissurata, A. ryanii, Sarcogyne brouardiana, S. coeruleonigricans, S. malpaiensis, and S. nogalensis. Three species, Acarospora coloradiana, A. peltastica, and A. utahensis are not treated as synonyms of A. strigata, a South American endemic. Thirty-four species of Acarosporaceae are reported from the Chihuahuan Desert in southern New Mexico. Fifty-six species of Acarosporaceae are reported from New Mexico. It is estimated that 416 species of described Acarosporales occur worldwide, most in need of revisions. Including species described or taken out of synonymy in this paper, there are 120 species of Acarosporaceae reported from North America north of Mexico. Caeruleum heppii is not a member of the Acarosporales. A key is supplied for 93 species of Acarosporaceae in the southwestern United States (Arizona, southern and central California, Nevada, New Mexico, Utah, and western Texas), which covers 77.5% of the described species in North America.