Abstract
Six new species are described: Acarospora anthracina, A. austrooccidentalis, A. oscurensis, and A. profusa from southwestern North America; A. aquatica from wetlands in eastern North America; and A. minuta from the Holarctic flora of Canada. In total, 13 species of Acarosporaceae with carbonized epihymenial accretions are known from North America. No European taxa of Acarospora or Sarcogyne with carbonized epihymenial accretions were found in North America, except A. lapponica, which is part of the Holarctic flora in Alaska, and the lichenicolous calciphyte Sarcogyne pusilla. A key to North American Acarosporaceae with carbonized epihymenial accretions is provided. Sarcogyne joshuaensis is transferred to Acarospora.