Algeria's geographic position, between the Mediterranean Sea and the desert, provides a valuable context for understanding lichen species distributions. However, lichens in this country remain poorly studied. To address this gap, 36 specimens of the genus Parmelia were collected from northern Algeria and analyzed using molecular phylogenetic methods and comprehensive chemical profiling. Four species of the genus Parmelia sensu stricto (P. omphalodes, P. saxatilis, P. sulcata, and P. submontana) have previously been reported from Algeria. In this study, the identities of P. sulcata sensu stricto and P. submontana were confirmed using molecular data. In addition, four species are newly reported for Algeria: Parmelia barrenoae, P. encryptata, P. neosaxatilis and P. serrana. Notably, all Algerian samples previously identified as P. saxatilis sensu lato are here reassigned to P. serrana, with one sample identified as P. neosaxatilis, suggesting that P. saxatilis sensu stricto may not occur in Algeria. A comprehensive chemical profiling of all specimens of selected Parmelia species is presented. Our results show that the combined analytical approaches using HPLC equipped with diode-array, evaporative light scattering, and mass spectrometric detectors, together with TLC (using UV detector and rhodamine 6G and sulfuric anisaldehyde reagents), enabled the straightforward detection of the discriminant metabolites α-methylene butyrolactones (lichesterinic acid derivatives) and lobaric acid. These compounds distinguish P. ernstiae from P. serrana and P. saxatilis sensu stricto. However, the chemical analyses did not allow differentiation among the three cryptic species P. encryptata, P. barrenoae and P. sulcata sensu stricto. This integrative approach to studying cryptic species may provide a framework for the determination of their precise biogeographical distributions. Keywords: Lichens, chemical diversity, molecular phylogeny, new records, HPLC-DAD-MS, cryptic species, North Africa.