Three new species of thelotremoid lichens (lichenized Ascomycota : Ostropales) with 15 new records of lichenized fungi from Thailand and a worldwide key to species of the genus Ampliotrema.

Three new species of thelotremoid lichens, Ampliotrema subglobosum Poengs. & Lumbsch, Ocellularia lichexanthonica Poengs. & Lumbsch and O. saxiprotocetrarica Poengs. & Lumbsch, are described and illustrated based on specimens from southern Thailand. Ampliotrema subglobosum is similar to A. globosum but differs by having larger ascospores with more septa. Ocellularia lichexanthonica differs from O. subdolichotata in ascomata diameter and by containing lichexanthone. Ocellularia saxiprotocetrarica is similar to O. gentingensis in ascospore length and the number of ascospore septa but has narrower ascospores and contains protocetraric acid. Fifteen species are reported for the first time for Thailand: Austrotrema bicinctulum (Nyl.) I. Medeiros et al., Baeomyces heteromorphus Nyl. ex C. Bab. & Mitt., Chapsa niveocarpa Mangold, Chiodecton sphaerale Ach., Erythrodecton malacum (Kremp.) G. Thor, Lecanora subjaponica L. Lü & H. Y. Wang, Leucodecton subcompunctum (Nyl.) Frisch, Myriotrema concretum (Fée) Hale, M. neoterebrans Frisch, Ocellularia khasiana (Patw. & Nagarkar) Kraichak et al., O. upretii S. Joshi et al., Pseudotopeliopsis scabiomarginata (Hale) Parnmen et al., Sulzbacheromyces sinensis (R. H. Petersen & M. Zang) Dong Liu & Li S. Wang, Thelotrema diplotrema Nyl., and T. isidiophorum (Kremp.) Zahlbr. Ampliotrema globosum (Hale) Poengs. & Lumbsch is proposed as a new combination. The genus Erythrodecton G. Thor is a new genus for the lichen flora of Thailand. [ABSTRACT FROM AUTHOR]