Lepidostoma(Mormomyia)lescheninew species, from Mt. Magazine, Arkansas, is described and illustrated. The new species is most closely related toL.(M.)griseum(Banks) andL.(M.)morseiWeaver of thegriseumspecies‐group, having oval‐shaped setose warts on the dorsum of abdominal segment IX and an acute apex on the main article of the inferior appendage. However,L. leschenihas straight rather than angled maxillary palpi, a flattened rather than circular segment X, and differences in wing venation. The forewing of the new species lacks a setose anal pocket, the setose median groove of the hindwing is poorly developed, and the thyridial cell of the hindwing is open. The new species is possibly endemic to the Ozark Mountain region. Six species ofLepidostomaare now known from the Interior Highlands of Arkansas, Missouri, and Oklahoma.