| A. confusa
|| concolorous to white-lined rims and spores 19-27 × 11-16 µm
| A. fumosa
|| olive to brown contrasting rims and spores 18-22 × 10-14 µm
Otherwise these two species are essentially the same. A. confusa is common in southern and central California. A. fumosa is uncommon in a few counties of southern caifornia.
Note: there are a few other gray, K- species on granitic rock, but most are bluish, with clearly green epihyenium, e.g. A. caesiocinerea and A. cyanescens. A. americana is common in AZ and Mexico, and has a “mottled” coloration.