Lichen nomenclature is in a chaotic state, and the usual sources offering information on it are poorly organised. The information provided here is a well-organised resource for the nomenclature of lichens and, to a lesser extent, of lichenicolous fungi. It includes information on nearly 100,000 names, some of which have never been catalogued elsewhere. You may find it a useful supplement to Index Fungorum, especially for older names.
This information was compiled largely independently of the usual sources, such as Index Fungorum and Zahlbruckner's Catalogus. Some of what you will find here differs from those sources. In most such cases, the information here is more likely to be correct, as I have consulted much original literature.
Here is a summary of lichen nomenclature (pdf) so far as I have been able to determine it. (Note added 29 Aug. 2017. Viewing with Firefox (which may hang or exhaust memory) or Opera (which may mangle the fonts) may fail. Internet Explorer and Chrome are OK. I haven't tested Edge or Safari. If you encounter such a problem, don't try to view the file within your browser. Instead, download it directly to your hard drive, and then view with Adobe Reader. For Opera, go to Settings / Websites / PDF Documents and check the box "Open PDF files in the default PDF viewer application". For Firefox, from the tools icon (top right) go to Options / Applications / Portable Document Format and set to anything except "Preview in Firefox". The file will then be downloaded directly to your default downloads directory. The pdf file itself appears to be OK. There are no problems reading it in Adobe Reader, and the bug is probably within the browsers themselves.)
If you work with old literature, you will often have to seek a basionym for a combination that is introduced cryptically. This list of epithets (pdf) is helpful for that purpose.