Frisch, A. 2006: Contributions towards a new systematics of the lichen family Thelotremataceae I. The lichen family Thelotremataceae in Africa. - Bibliotheca Lichenologica92: 3-370. [RLL Suppl.] Abstract: A new genus classification of the Thelotremataceae is presented. Myriotrema, Ocellularia and Thelotrema sensu HALE (1980, 1981) were found to be heterogeneously circumscribed and were segregated into more natural units. The following changes are made: Ampliotrema Kalb is validated, and Chapsa Massal., Leptotrema Mont., Leucodecton Massal. and Stegobolus Mont. are resurrected. The genera Acanthotrema A. Frisch, Gyrotrema A. Frisch, Melanotrema A. Frisch and Redingeria A. Frisch are described as new to science. 19 genera are accepted for the family: Acanthotrema, Ampliotrema, Chapsa, Chroodiscus, Diploschistes (not treated), Fibrillithecis, Gyrotrema (part II), Ingvariella (not treated), Leptotrema, Leucodecton, Melanotrema (part II), Myriotrema, Nadvornikia (not treated), Ocellularia, Redingeria (part II), Reimnitzia, Stegobolus (part II), Thelotrema and Topeliopsis. The Thelotrema glaucopallens- and the Ocellularia clandestina-group are of uncertain generic affiliation. The following generic synonyms are accepted: - Asteristion Leight.; Thelotrema subgen. Asteristion (Leight.) T. Matsumoto (= Chapsa). - Ocellularia sect. Chroodiscus Müll. Arg.; Phyllophthalmaria sect. Chroodiscus (Müll. Arg.) Zahlbr.; Phyllobrassia Vain. (= Chroodiscus). - Thelotrema sect. Tremotyliopsis Zahlbr. (= Fibrillithecis). - Enterostigma Müll. Arg.; Chiodecton subgen. Enterostigma (Müll. Arg.) Vain.; Enterostigmatomyces Cif. & Thomas. (= Leucodecton). - Coscinedia Massal.; Ocellis Clements (= Myriotrema). - Ascidium Fée; Antrocarpon G. Mey. emend. Massal.; Ectolechia Massal.; Porophora G. Mey. (= Ocellularia). - Antrocarpum G. Mey.; Brassia Massal.; Thelotrematomyces Thomas. (= Thelotrema). Approximately 1300 specimens collected during field work in Cameroon and Tanzania were investigated for this revision of the African Thelotremataceae, together with the relevant type material and c. 120 specimens obtained from public herbaria. From 73 taxa of the Thelotremataceae recorded from Africa 38 are accepted as valid species. L. monosporum sensu CENGIA SAMBO (1937; = Porina), O. scolecospora Dodge (= Lecidea stictidea Nyl.), T. cameroonensis Dodge (= Laurera megasperma (Mont.) Zahlbr.) and T. zenkeri Dodge (= Porina) are excluded from the family, while the types of O. bonplandiae (Fée) Spreng. sensu MÜLLER ARG. (1895a), O. cinerascens des Abbayes, O. myriopora (Tuck.) Müll. Arg. sensu MÜLLER ARG. (1895a), Ph. poncinsiana Hue, Ph. uber Hue and T. umbonatum Müll. Arg. were not available for examination. Together with 17 species described as new to science (see below and part II), O. vezdana nom. nov. and 47 species recorded for the first time from Africa, a total of 94 species is presently known from this continent. 50 species were collected in Cameroon as compared to 47 species in Tanzania. The highest species diversity wwas found in lowland rainforests in Cameroon (45 species) and in the Eastern Arc Mountains in Tanzania (37 species). In contrast, there are only few species in the high altitude forests, mangrove forests, secondary forests and plantations, and in all drier forest types. Country checklists are compiled for the African Thelotremataceae, and the species inventory is listed for the more important habitat types and collection sites in Cameroon and Tanzania. The African C. alstrupii A. Frisch, C. kalbii A. Frisch, Le. biokense A. Frisch, Le. sorediiferum A. Frisch, My. neoterebrans A. Frisch, O. africana A. Frisch, O. bipindensis A. Frisch, O. cameroonensis A. Frisch, O. eumorphoides A. Frisch, O. flavisorediata A. Frisch, O. zenkeri A. Frisch, T. euphorbiae A. Frisch and T. zimbabwense A. Frisch are described as new to science. A. brasilianum (Hale) A. Frisch, C. alborosella (Nyl.) A. Frisch, C. cinchonara (Fée) A. Frisch, C. indica Mont., C. leprieurii (Mont.) A. Frisch, C. leprocarpa (Nyl.) A. Frisch, C. patens (Nyl.) A. Frisch, C. platycarpella (Vain.) A. Frisch, C. pseudophlyctis (Nyl.) A. Frisch, C. zahlbruckneri (Redinger) A. Frisch, F. insignis (Zahlbr.) A. Frisch, F. vernicosa (Zahlbr.) A. Frisch, Le. fissurinum (Hale) A. Frisch, Le. occultum (Eschw.) A. Frisch, Le. subcompunctum (Nyl.) A. Frisch, M. meiospermum (Tuck.) A. Frisch, M. platystomum (Mont.) A. Frisch, Myriotrema glaucophaenum (Kremp.) Hale, My. microporellum (Nyl.) Hale, My. olivaceum Fée, My. terebratulum (Nyl.) Hale, O. bahiana (Ach.) A. Frisch, O. clandestina (Ach.) Müll. Arg., O. eumorpha (Stirton) Hale, O. massalongoi (Mont.) Hale, O. cf. minutula Hale, O. perforata (Leight.) Müll. Arg., O. postposita (Nyl.) A. Frisch, O. pyrenuloides Zahlbr., O. cf. subsimilis Hale, O. spec. 1, O. spec. 2, R. leiostoma (Tuck.) A. Frisch, Re. santensis (Tuck.) Kalb, S. actinotus (Tuck.)A. Frisch, S. crassus (Müll. Arg.) A. Frisch, S. emersus (Kremp.) A. Frisch & Kalb, S. subcavatus (Nyl.) A. Frisch, T. antonini Purvis & P. James, T. bicinctulum Nyl., T. canarense Hale, T. leucomelaenum Nyl., T. monosporum Nyl., T. pachysporum Nyl., T. porinoides Mont. & Bosch, T. cf. subexpallescens Nagarkar, Sethy & Patw. and T. subarmellense ad interim are recorded for the first time from Africa. Further new combinations include: C. diploschistoides (Zahlbr.) A. Frisch, C. eitenii (Hale) A. Frisch, C. platycarpa (Tuck.) A. Frisch, C. recurva (Salisbury) A. Frisch, F. platyspora (Harm.) A. Frisch, Le. compunctellum (Nyl.) A. Frisch, Le. glaucescens (Nyl.) A. Frisch, Le. elachistoteron (Leight.) A. Frisch, Le. nuwarense (Hale) A. Frisch, Le. tarmaguliense (Sethy, Nagarkar & Patw.) A. Frisch, My. plurifarium (Nyl.) A. Frisch. The following combinations are validated: Am. auratum (Tuck.) Kalb, Am. amplius (Nyl.) Kalb, Am. discolor (Ach.) Kalb, Am. lepadinoides (Leight.) Kalb and Am. palaeoamplius (Aptroot & Sipman) Kalb. New synonyms accepted for the African species include: Ascidium punctulatum Leight. (= O. cavata), Graphina pseudophlyctis var. monospora Redinger (= C. pseudophlyctis), Graphis lynceodes Nyl. (= M. platystomum), Lecanactis? confluens var. calcea Mont. (= C. pseudophlyctis), L. compunctum var. purpuratum Müll. Arg. (= Le. occultum), L. endoxanthellum Zahlbr. (= O. leioplacoides), My. subcostaricense Sipman (= My. glaucophaenum), O. capensis var. feracior Zahlbr. (= O. henatomma), O. capensis var. leiothallina Zahlbr. (= O. henatomma), O. comparabilis var. microcarpa Redinger (= O. terebrata), O. comparabilis var. plicatula Redinger (= O. terebrata), O. endoleuca Müll. Arg. (= O. auberianoides), O. galactina Zahlbr. (= My. microporum), O. scolecospora Dodge (= Lecidea stictidea Nyl.), O. subperforata Nagarkar, Sethy & Patw. (= O. perforata), O. violacea Räsänen (= O. perforata), O. violacea var. glauca Räsänen (= O. perforata), Pyrenula trypanea Ach. (= O. terebrata), T. albescens Vain. (= C. indica), T. cameroonensis Dodge (= Laurera megasperma), T. cavatum var. submutatum Nyl. (= O. perforata), T. compunctum var. antillarum Vain. (= Le. occultum), T. compunctum var. praiense Vain. (= Le. occultum), T. colobicum Nyl. (= C. leprocarpa), T. comparabile Kremp. (= O. terebrata), T. deightonii Dodge (= C. pseudophlyctis), T. emergens Vain. (= My. glaucophaenum), T. flavescens Darb. (= T. lepadinum), T. laevigans Nyl. (= O. clandestina), T. laevigans f. avertens Nyl. (= O. clandestina), T. loandense Vain. (= Le. occultum), T. osornense Dodge (= T. lepadinum), T. platycarpoides Tuck. (= C. platycarpa), T. pycnophragmium Nyl. (= C. indica), T. subterebratum Nyl. (= My. microporellum) and Urceolaria compuncta Ach. (= Le. occultum). The following taxa are accepted as valid species: C. platycarpella (Vain.) A. Frisch (previously included in C. alborosella), O. mozambica Vain. (previously included in O. discoidea), T. bicinctulum (previously included in T. subtile), T. pachysporum Nyl. (previously included in T. lacteum). Lectotypes are selected for Ascidium interpositum Nyl., A. postpositum Nyl., O. comparabilis var. microcarpa Redinger, Phaeographina zahlbruckneri Redinger, Porina compuncta Ach., T. albidum Nyl., T. bicinctulum Nyl., T. capense Zahlbr., T. leioplacoides Nyl., T. leucastrum Tuck., T. monobactrium var. geminipara Vain. and T. pycnophragmium Nyl. Precise lectotypes are specified for T. disciforme Leight., T. discoideum Ach., T. obturatum Ach., T. pachystomum ssp. piluliferum Tuck., T. perforatum Leight. and T. platycarpoides.