[in Spanish with English abstract: ] On the southern bank of the Río de la Plata there is a forest ecosystem that has suffered the ravages of urbanization, which is known as jungle or gallery forest. Within this ecosystem there is a recently formed natural reserve: the Municipal Reserve “Eco Area of Avellaneda”, which is surrounded by one of the most populated areas in the country. Epiphytic lichen species were surveyed. A total of 43 species were found. Comparisons were made by means of β diversity indices, with the other nearby reserves. Finding that the Eco Area presents the least richness of the three, finding mostly heliophilous species. Regarding the diversity analysis, it is observed that the ecoarea is similar to the Punta Lara Nature Reserve, although the turnover analysis shows that the least change of species occurs between Punta Lara and Martín García Island, which may be explained by the time of protection presented by these reserves. The protection of this type of urban reserves is essential to help the conservation of lichens in the province of Buenos Aires, since this environment is seriously affected. Key words. Lichens; Buenos Aires; gallery forest; β diversity.