Taxonomic delimitation within the Andean Festuca setifolia complex s. l. has been fraught with difficulty due to the large range of morphoanatomical and epidermal variation among species coupled with varying opinions on what diagnostic characters should be used to distinguish species. We shed light on this through using multivariate analysis (PCA, PCoA and cluster analysis), based on 20 variables (morphoanatomical and epidermal characteristics), to elucidate patterns of variation within this group and to test the validity of current species delimitations. The analysis of 89 OTU's recognized six clearly separated groups, corresponding to F. fiebrigii, F. hieronymi, F. lilloi, F. linigluma (a new species described here), F. samensis, and F. setifolia. The OTU's corresponding to F. fiebrigii were grouped as outliers with respect to the F. setifolia complex s. l. and were excluded from multivariate analysis. We redefine the F. setifolia complex s. s. to include F. linigluma, F. lilloi, and F. setifolia, which possess unique characters differentiating them from other members of the complex s. l. The status of type material was clarified, with F. tucumanica synonimised under F. lilloi, while F. erecta var. mutica, F. erecta var. aristulata, and F. dissitiflora var. loricata, F. weberbaueri, F. dissitiflora var. villipalea, and F. hieronymi subvar. expansa were placed as synonyms of F. fiebrigii, with the taxonomic concept of F. fiebrigii being redefined. We present an identification key, descriptions, illustrations, and revised geographic ranges for F. fiebrigii and the species of the F. setifolia complex s. l., including the new species, Festuca linigluma, from the central Andes.