Background: Lichen diversity in the Mexican state of Aguascalientes has historically been neglected. Lichen species in all vegetation types, except for the arid zones, remain underexplored.Hypotheses: Lichenized fungi richness reported for Aguascalientes will increase due to exploration and collecting activities in vegetation types other than xerophilous scrubs. This will allow finding species of interest for conservation purposes, including Mexican endemics and/or threatened taxa.Data description: Lichenized fungi, vegetation types, substrates. Study site and dates: Mexican state of Aguascalientes, 2018 to 2021. Methods: Revision and taxonomic identification of lichenized fungi specimens deposited at the HUAA herbarium. Once the endemic species were detected, the Extent of Occurrence (EOO) and the Area of Occupancy (AOO) were calculated to assess their conservation status according to the IUCN Red List.Results: 162 new records were found for Aguascalientes. Chrysothrix insulizans R.C. Harris & Ladd, Hertelidea botryosa (Fr.) Kantvilas & Printzen, and Sarcogyne novomexicana H. Mag., were new records for the country. The epiphytic substrate and the foliose growth form were dominant. Parmotrema acutatum had an EOO = 192,141 km2, while Phaeophyscia sonorae had a EOO = 18,285 km2.Conclusions: The number of lichenized fungi species recorded for Aguascalientes increased to 218. We suggest publication of Parmotrema acutatum Kurok. as Least Concern (LC) and Phaeophyscia sonorae Essl. as Vulnerable (VU) in the IUCN Red List. conservation, endemic species, lichens, oak forest, subtropical shrubland