Odontosema anastrephae Borgmeier is a figitid parasitoid of Anastrepha fruit fly larvae infesting fallen fruit. It is of potential use in biological control as a complement to parasitoids that attack larvae infesting fruit still on the tree and to parasitoids that can only oviposit into larvae near the surface of the fruit, because Odontosema pursues larvae deep within the pulp. A newly discovered Mexican all-female (presumably thelytokous) population, provisionally referred to here as O. near anastrephae, appears to be morphologically indistinguishable from arrhenotokous individuals. Thelytokous reproduction can potentially lower costs in mass rearing facilities and increase parasitoid efficacy in the field. PCR amplification and sequencing of mitochondrial (COI) and nuclear (ITS2) genetic sequences suggested that these populations are genetically distinct, but no more so than often occurs among distinct populations within recognized species. In addition to the description of an all-female population of Odontosema, this study presents the first genetic sequence data for members of the genus Odontosema, enabling phylogenetic comparison between Odontosema and other figitid genera and the development of methods for the identification of Odontosema species by PCR. The implications of thelytoky for a cladistic definition of speciation, especially for newly diverging populations such as these, as well as the potential practical implications of our findings for fruit fly biological control, are discussed.