Saxicolous Lichens in the Semi-Arid Caatinga in Brazil Show Substratum Shifts

ABSTRACT Saxicolous lichens were investigated for the first time in the southern reaches of the Caatinga biome in Sergipe, NE Brazil. Only 20 species could be identified, and three more are described as new to science: Cresponea quinqueseptata Aptroot & M.Cáceres, sp. nov. with 5-septate ascospores and yellow pruinose discs; Fulgogasparrea intensa Aptroot & M.Cáceres, sp. nov. with a cinnabar red, appressed thallus with marginally elongated lobes; and Peltula nigrotestudinea Aptroot & M. Cáceres, sp. nov. with flat, black, isolated areoles. A number of substrate shifts was observed: 1) the new species of Peltula Nyl. does not grow in places with run-off as usual, but on top of the boulders, where it is in the best position to catch the precipitation, which is the limiting factor here; 2) Synalissa matogrossensis (Malme) Henssen, which was previously known only from the type locality, where it grows on limestone, was found on granite; the apparently considerable width of its ecological amplitude is unusual. Its position inside the Lichinaceae was confirmed by sequence data; 3) Xanthoparmelia succedans Elix & J.Johnst. was found growing on bark, rather high on trees. The corticolous occurrence is attributed to high diaspores pressure; 4) the area and thus the tree bark is wet enough part of the year to sustain the growth of a corticolous Lichinaceae (one of only two compared to 340 saxicolous and terricolous species in the family) and other cyanophilic lichens; and 5) the new Cresponea Egea & Torrente is the first saxicolous species in the genus in the tropics, where the genus is most speciose; its thallus is deeply endolithic.