Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Notes: Because the genus is now regarded as monotypic, a generic description would simply recapitulate the specific description given below. Two other genera have been proposed: Tornabenia Trevis. and Tornabeniopsis Follmann, but the former is a nom. illegit and the latter is nom. inval. (Nimis and Tretiach 1997).