Diversidad de macrolíquenes saxícolas en México: caso de estudio del distrito minero de Guanajuato

Background and Aims:  The diversity of saxicolous macrolichens in the state of Guanajuato is little known. The available information is limited to isolated notes of collections and species in specialized electronic pages. The objective of this work was to contribute through the development of a floristic list to the knowledge of the diversity of the saxicolous macrolichens in four localities (mountain “La Bufa”, ecological park “El Orito”, panoramic highway “El Pipila” and Sierra de Santa Rosa de Lima). Methods:  The specimens were collected and subsequently determined using specialized keys, considering their morphological, anatomical and chemical characteristics. This was based on stereoscopic and composite microscope observations, response to chemical reagents and, in some cases, thin layer chromatography. Finally, descriptions of the species were reviewed and the specimens were compared with those existing in the herbarium EBUM of the Universidad Michoacana de San Nicolas de Hidalgo. Key results:  A list of 42 species is presented for the mining district of Guanajuato, which constitute new records for the studied localities; 23 are new records for Guanajuato and one is new for Mexico. Conclusions:  Of the 42 species presented in this study, the family Parmeliaceae is the most representative of the study area, especially the genus  Xanthoparmelia  with nine species, of which three are new records for the state of Guanajuato and one of them is new for Mexico. The zone of La Bufa with semi-warm climate and the ignimbrita like dominant rock reunites the majority of the registered species. The species of the families Cladoniaceae, Usneaceae, Ramalinaceae and Stereocaulaceae are representative of the zone of Santa Rosa de Lima dominated by a humid climate and the rhyolite tuff-like main rock.