A new species in the genus Acarospora (Acarosporaceae, lichenized ascomycetes), from Darel Valley, Gilgit Baltistan, Pakistan, is described and illustrated here under the name Acarospora sultanii. It is characterized by brown to blackish white thallus, thicker epihymenium 40-60 mu m, taller hymenium 120-160 mu m, and larger ascospores 15-25 x 5-9 mu m. Phylogenetic analysis based on ITS-nrDNA sequencing placed our species relative to A. nodulosa. Descriptions and images of the new species are provided, as well as a key for Pakistani species of Acarospora. phylogenetic analyses, taxonomy, lichen diversity, internal transcribed spacer