Aulacorthum sp. collected on Artemisia princeps and Artemisia stolonifera (Asteraceae) in the Korean Peninsula was compared with the eight Aulacorthum species using molecular and morphological characters. In the sequence analysis, the genetic divergences of two mitochondrial genes, COI and CytB, between Aulacorthum sp. and the congeneric species were higher than those among the congeneric species. In the morphometric analysis, principal components analysis using 13 morphological characters reveals that Aulacorthum sp. is distinguished from the congeneric species, especially Aulacorthum albimagnoliae, which is morphologically most similar to Aulacorthum sp.. Based on these results, we propose a new species, Aulacorthum (Aulacorthum) artemisiphaga Lee, Havelka, and Lee sp. nov., with a description of apterous and alate viviparous females and an identification key to species in the genus Aulacorthum in the Korean Peninsula based on apterous viviparous females.