In the context of the revision of Amaryllidaceae tribe Griffinieae that we are preparing, we describe and illustrate a new species, Griffinia albolineata, known from a single fragment of the Atlantic Forest in the Brazilian State of Minas Gerais. It is distinguished by the foliar blade with a whitish longitudinal stripe and long-acuminate apex, unique features among the large-sized species of the genus. Additionally, we present a taxonomic reassessment of G. intermedia, described two centuries ago and historically of very uncertain identity. We provide a description and detailed distribution data, previously unpublished records, and photographs of the species in its natural habitat. We also compare the foliar anatomy and surface micromorphology of the two species. The conservation status of the two species is informally evaluated, and both are tentatively considered endangered. An identification key to the large-sized species of the genus is presented Ver menos