Members of the genus Lysiphlebus Foerster are medium-sized endoparasitoid aphidiine wasps with over 30 species distributed worldwide. They attack numerous aphid hosts, and some species are important biological control agents. All European Lysiphlebus species are revised based on sequence information from the mitochondrial COI barcoding gene and the nuclear 28SD2 gene, morphological traits, and on information about their host specificity. The taxonomic status of 13 European Lysiphlebus species is confirmed, while 11 are redescribed and illustrated. The following four Lysiphlebus species are synonymized: L. melandriicola Starý, 1961 = L. fabarum (Marshall, 1896), L. hirtus Starý, 1985 (= L. confusus Tremblay & Eady, 1978), L. hispanus Starý, 1973 (= L. desertorum Starý, 1965), and L. safavii Starý, 1985 (= L. hirticornis Mackauer, 1960). Two new Lysiphlebus species are described: L. volkli sp.n. and L. brachycaudi sp.n. Our results, based on both COI and 28SD2, confirm the existence of three monophyletic species groups within the genus: (1) the ‘fabarum’ group, which includes L. fabarum, L. cardui (Marshall, 1896), L. confusus, L. hirticornis, L. brachycaudi sp.n., and L. volkli sp.n.; (2) the ‘testaceipes’ group, which includes L. testaceipes (Cresson, 1880), L. orientalis Starý & Rakhshani, 2010, L. fritzmuelleri Mackauer, 1960, L. balcanicus Starý, 1998, L. desertorum, and probably L. dissolutus (Nees, 1811); and (3) the ‘alpinus’ group, consisting solely of L. alpinus Starý, 1971. Geometric morphometrics of fore wing shape proved to be a powerful tool to delineate sibling species within the ‘fabarum’ group. We were able to confirm for the first time sexual lines of L. cardui and L. confusus. Furthermore, an additional potentially asexual Lysiphlebus taxon in Europe is revealed based on the discovery of an asexual line of L. volkli sp.n. in Iran. An illustrated key for identification of the European Lysiphlebus species is provided.

Morphological divergence often increases with phylogenetic distance, thus making morphology taxonomically informative. However, transitions to asexual reproduction may complicate this relationship because asexual lineages capture and freeze parts of the phenotypic variation of the sexual populations from which they derive. Parasitoid wasps belonging to the genus Lysiphlebus Foerster (Hymenoptera: Braconidae: Aphidiinae) are composed of over 20 species that exploit over a hundred species of aphid hosts, including many important agricultural pests. Within Lysiphlebus, two genetically and morphologically well-defined species groups are recognised: the “fabarum” and the “testaceipes” groups. Yet within each group, sexual as well as asexual lineages occur, and in L. fabarum different morphs of unknown origin and status have been recognised. In this study, we selected a broad sample of specimens from the genus Lysiphlebus to explore the relationship between genetic divergence, reproductive mode and morphological variation in wing size and shape (quantified by geometric morphometrics). The analyses of mitochondrial and nuclear gene sequences revealed a clear separation between the “testaceipes” and “fabarum” groups of Lysiphlebus, as well as three well-defined phylogenetic lineages within the “fabarum” species group and two lineages within the “testaceipes” group. Divergence in wing shape was concordant with the deep split between the “testaceipes” and “fabarum” species groups, but within groups no clear association between genetic divergence and wing shape variation was observed. On the other hand, we found significant and consistent differences in the shape of the wing between sexual and asexual lineages, even when they were closely related. Mapping wing shape data onto an independently derived molecular phylogeny of Lysiphlebus revealed an association between genetic and morphological divergence only for the deepest phylogenetic split. In more recently diverged taxa, much of the variation in wing shape was explained by differences between sexual and asexual lineages, suggesting a mechanistic link between wing shape and reproductive mode in these parasitoid wasps.

Using CO1 sequence analysis, we investigated the relationships of Western Palearctic and Nearctic Cotesia that spin aggregated cocoons in the shape of a ball, and as adults are morphologically very similar. The analysis included the conceptual taxa C. tibialis, C. ofella, C. vanessae, C. ruficrus, C. xylina and C. yakutatensis, as well as the newly described species C. trivaliaesp. nov. The examined specimens of C. tibialis, C. ofella, C. vanessae, C. ruficrus and C. trivaliaesp. nov. were collected in several European countries, and C. xylina and C. yakutatensis in Canada and the USA. Molecular analyses showed that C. ruficrus is not closely related to the other studied taxa. Based on the genetic distances as well as biology and morphology, C. vanessae and C. ofella are confirmed as solid taxa. The species C. yakutatensis comprises two entities. Having 8 haplotypes, C. tibialis also emerges as a species complex, divided into two clusters. With 26 detected haplotypes, C. xylina shows the highest diversity, being composed of three segregates. The conceptual species C. tibialis, C. xylina and C. yakutatensis seem to be species complexes containing several candidates for recognition as distinct species. One from the European C. tibialis complex is here described as new, and the impediments to be overcome before the description of further species are outlined.