Aster xuelinii, a new species from Gansu Province, China, is described and illustrated based on morphological and phylogenetic evidence. The new species is superficially similar to A. dolichopodus Y. Ling in that both have nearly entire leaves, synflorescence solitary at branch tips or arranged in corymbiform clusters, and ray floret color. However, it differs from A. dolichopodus in having peduncles 6–9 cm in length and 12–14 ray florets, versus 2.5–15 cm in length and 19–26 ray florets. Phylogenetic analyses of nuclear ribosomal ITS and ETS sequences, as well as the chloroplast trnL-F region, place this new species within the genus Aster, where it forms a well-supported clade with A. taliangshanensis Y. Ling. A. xuelinii differs from A. taliangshanensis in that the latter has stems often purplish-red in the upper part, capitula typically arranged 1–3 at branch tips forming a loosely corymbiform synflorescence, and a higher number of ray florets (50–60), which are bluish-purple. Furthermore, detailed morphological descriptions, diagnostic illustrations, and ecological habitat characteristics are provided, supporting the classification of this new species.

Key words: Aster, Gansu, molecular phylogeny, morphological characters, new taxon