AbstractThe first data on the interaction between a phytophagous hoverfly and holoparasitic broomrape plants in Europe is reported. Description of the new species Eumerus larvatus sp. nov. Aracil, Grković et Pérez-Bañón is presented from specimens feeding within the fleshy hypogeal stems of Cistanche phelypaea in different localities of Southeast of Iberian Peninsula. Both, adult and preimaginal morphology are studied, including also a molecular analysis based on COI gene sequences. The molecular data, together with the diagnostic morphological characteristics of the adult, indicate that the species belongs to the Eumerus tricolor species-group. This paper presents the first in-depth and detailed description of the preimaginal morphology of a representative of this species group, based on scanning electron microscopy (SEM) images.