Taxonomic and biological observations on the genus Lichenoconium (Sphaeropsidales)

A revision of the genus Lichenoconium Petr. & Syd. (Sphaeropsidales) is presented. Ten species are accepted including L. echinosporum D. Hawksw., L. erodens M.S. Christ. & D. Hawksw. and L. parasiticum D. Hawksw. sp. nov. and L. cargillianum (Linds.) D. Hawksw. and L. usneae (Anzi) D. Hawksw. combs. nov. All species apart from L. boreale (Karst.) Petr. & Syd. are exclusively lichenicolous and species of the genus certainly occur on 58 host lichens (with unconfirmed reports for a further 11). Up to three Lichenoconium species can occur on a single host but when this arises different symptoms often result. Descriptions of the accepted species and details of the reactions of various hosts to them are presented; a key and table summarising their differences is included. The species are delimited on the basis of their anatomy and morphology without regard for the host genera infected; some then prove to be restricted to particular host genera whilst others occur on several. The identities of five excluded taxa are discussed, and it is emphasized that as currently conceived the genus is not natural and that both L. boreale and L. pertusariicola (Nyl.) D. Hawksw. will eventually require transference to other genera when generic concepts in allied non-lichenicolous fungi have been clarified. Scanning electron micrographs of conidia of most species treated are included.