Morphological and genetic variability of Cotesia tibialis species complex (Hymenoptera: Braconidae: Microgastrinae)

Cotesia tibialis is a gregarious koinobiont parasitoid of lepidopteran larvae. Due to the wide range of variability of some morphological traits, several new species were already described from the C. tibialis complex. Nixon left open the possibility that there are more by recognizing two seasonal forms. To investigate whether there are hidden taxa within C. tibialis, of 14 samples we analysed morphological characters such as the colouration of female hind femora and male antennae, and the colour and structure of the mass cocoons. The results of the analyses of the colouration of female hind femora and cocoons refute the previously defined forms within C. tibialis. Using the method of geometric morphometrics to investigate the shape of the females’ fore wings, we also did not find support of the existence of two seasonal forms of C. tibialis. Finally, applying the mitochondrial barcoding region COI the genetic differences between selected C. tibialis morphotypes were analysed. Based on both morphological and molecular analyses, one morphotype obtained from smoke-white cocoons was completely discriminated against all others, indicating that it is a potentially new species, or one of those already described which Nixon returned to C. tibialis as a synonym. The status of the other 13 morphotypes is still unclear and requires further analyses.