Variability in the spermathecal form of the three closely-related species ascribed to the Curtonotum cuthbertsoni species-group, cuthbertsoni complex, namely: C. cuthbertsoni Duda, C. saheliense Tsacas and C. simile Tsacas, is investigated. Pairs of spermathecae are illustrated photographically and their form compared intra- and interspecifically. The external form and shape are found to overlap in all three species. The spermathecae of C. simile are illustrated for the first time. While general trends in shape are noted, variation is overlapping, both between individuals of the same species and within pairs of spermathecae from the same specimen. It is concluded, therefore, that spermathecal form is not a useful character to distinguish females of the three species, and that the use of spermathecae as diagnostic characters in the genus Curtonotum Macquart, in general, must be viewed critically and with a high degree of scepticism.