The female of Eremobittacus spinulatus Byers, 1997 is described for the first time. A key to the two species known of this genus endemic to Mexico is provided, and species distribution is illustrated. A case is made for adults of Eremobittacus to be sexually dimorphic, which appears to be an exceptional occurrence in Bittacidae . It is claimed that Eremobittacus spinulatus habitus has a wasp-like appearance, which may potentially depict a case of mimicry.