A small insertion in the SSU rDNA of the lichen fungus is a degenerate group I intronv. 29582–586
Grube, M., Gargas, A., and DePriest, Paula T. 1996. "A small insertion in the SSU rDNA of the lichen fungus Arthonia lapidicola is a degenerate group I intron." Current genetics, 29 582–586.