Acanthothecis and other graphidioid lichens with warty periphysoids or paraphysis-tips

The occurrence of spiny paraphysis-tips and/or periphysoids in lichenized a scomycetes has been till now only reported from 3 species of Acanthothecis and 1 species of Chroodiscus. We add 29 more species, mostly members of the Lichen family Graphidaceae. Descriptions of all hitherto known species wit h this character as well as generic concepts for the genera Fissurina and A canthothecis (Graphidaceae) are provided. In Acanthothecis three new species are described: Acanthothecis gracilis, A . mirabilis and A. obscura. Thirteen species formerly described in the gene ra Graphis or Graphina are combined to Acanthothecis: Acanthothecis abaphoi des (= Graphina abaphoides), A. albescens (= Graphis albescens), A. consoci ans (= Graphis consocians), A. corcovadensis (= Graphina corcovadensis), A. hololeucoides (= Graphina hololeucoides), A incondita (= Graphina incondit a), A intertexta (= Graphis intertexta), A. leucolyta (= Graphina leucolyta ), A. leucoxantha (= Graphis leucoxantha), A. sanguinoloba (= Graphis sangu inoloba) A. silicicola (= Graphis silicicola), A tetraphora (= Graphina tet raphora). Acanthothecium clavuliferum is formally combined to Acanthothecis . Three species that are well distinguishable from the others are mentioned , but are not formally described as new for science as the material is too scarce: A. bicellulata ad int. A. farinosa ad int. and A. subabaphoides ad int. The genus Fissurina Fee based on Fissurina dumastii (Lectotype selected her e) is reintroduced. Two species in the genus Fissurina - F. dumastii and F. instabilis - show s piny periphysoids and paraphysis-tips and are treated here. Within the family Graphidaceae, seven further species with spiny periphysoi ds are recognized: Graphina amicta, Graphina marcescens, Graphis candidata, Graphis chionophora, Graphis cf. sauroidea, Phaeographina crassa, Graphina subalbotecta ad int. They share several characters and seem to form a natu ral group but so far no systematic conclusions are drawn from these observa tions. Four species with spiny paraphysis-tips and periphysoids do not belong to t he family Graphidaceae: Chroodiscus brasilianus is a member of the closely related family Thelotremataceae; the other three species are of uncertain s ystematic position and could not be identified with the available keys or d escriptions. We List them with their herbarium accession numbers. The following species are reduced into synonymy: Graphina atractospora (= A canthothecis abaphoides), Acanthothecis pachygraphoides (= A. hololeucoides ), Acanthothecis caesio-carnea (= A. hololeucoides), Graphis singaporina (= Graphis candidata), Thelotrema carneoradians (= Chroodiscus brasilianus). All species are provided with detailed descriptions; drawings and photograp hs illustrate the most important characters. The species and their chemical compounds are listed in a table. Keys for all hitherto known species with spiny periphysoids and paraphysis- tips, as well as for all known Acanthothecis-species, are included.