Results of a lichenological and bryological exploration of Cerro Guaiquinima (Guayana Highland, Venezuela)

214 Lichen and 38 bryophyte species are reported from Cerro Guaiquinima, a sandstone table mountain in southeastern Venezuela, thus far almost unexplored for these groups and apparently undisturbed by man. Slightly over half of these species have also been reported from the north slope of Mount Roraima and surroundings, a nearby area with similar edaphic and climatological conditions. Altitudinal differences in the flora are probably largely dependent on differences in vegetation structure: the closed froests at the foot harbour more Cladoniaceae and Trypetheliaceae are found. On the highest site bryophytes are more frequent. First descriptioins are given for nine lechens and one moss: Buellia bellardii Sipman, Hypotrachyna adaffinis Sipman, Myriotrema flavolucens Sipman, Myriotrama squamuloides Sipman, Ocellularia croceoisidiata Sipman, Ocellularia glaucoglyphica Sipman, Thelotrema caarneoradians Sipman, Thelotrema guaiquinimae Sipman, Sphagnum sipmanii Crum and Ocellularia sinuosa Sipman (in appendix, from Colombia). Myriotrema guianense is reduced to synonymy of Myriotrema columellatum (A. Zahlbr.) Sipman, comb. nov.