The present study tested the hypothesis that species richness and composition of epiphytic microlichens can be used to support the phytosociological differentiation between Caatinga and Brejos de Altitude, as exemplified by the Muralha Reserve (Caatinga) and the Parque Estadual Mata do Pau Ferro (Brejo de Altitude), in the state of Paraíba, Brazil. A total of 755 lichen samples were collected, comprising 18 families, 42 genera and 111 species of epiphytic, corticolous microlichens. Overall species richness was higher in the Caatinga, with 67 species, compared to the Brejo, with 46 species. Species richness per sample was significantly higher in the Caatinga compared to the Brejo. Taxonomic composition also differed significantly between the two areas, with Arthoniaceae, Caliciaceae, Chrysothrichaceae, Graphidaceae (particularly Graphis), Lecanoraceae, Mycoporaceae, Pertusariaceae, and Trypetheliaceae being dominant in, or exclusive to, the Caatinga, whereas Coenogoniaceae, Graphidaceae (Diorygma, Fissurina, Myriotrema, Ocellularia, Phaeographis, Sarcographa), Malmideaceae, Porinaceae and Strigulaceae were dominant in, or exclusive to, the Brejo. Five new species were discovered as result of this study. This is the first study to quantitatively compare richness and community patterns of epiphytic microlichens between two major biomes in Northeastern Brazil, and the first detailed lichen study in the state of Paraíba.

São apresentados 25 novos registros para o Estado (toponímia) de Alagoas, sendo uma espécie novo registro para a região Nordeste e quatro outras novas ocorrências para o Brasil. Uma lista com todas as espécies atualmente conhecidas para o semi-árido de Alagoas é apresentada. As amostras foram coletadas na região do Município de São José da Tapera, estado de Alagoas, onde ocorre uma rica vegetação de Caatinga arbóreo-arbustiva.az de regenerar e recrutar em ambientes sombreados, mas o crescimento é limitado pelas condições de pouca luminosidade.

A total of 25 species are here reported for the first time for Alagoas State, with one new record for the Northeastern Region of Brazil and four new records for Brazil. A list of all known species for the semi-arid region in Alagoas is presented. Sampling took place near the municipality of São José da Tapera, in the semi-arid region of Alagoas, where a very rich Caatinga vegetation of trees and shrubs occurs.