Taxonomic analysis of Lachnus pallipes/longirostris–roboris complex (Hemiptera, Aphididae, Lachninae), with the redescription of sexual morphs and new synonymy

The aphid genus Lachnus contains some species of uncertain taxonomic status, described either as separate species despite having similar morphology, or as host plant races. The separation of L. pallipes and L. longirostris exemplifies this uncertainty. Following a detailed morphological analysis and the application of molecular markers COXI and COXII, their taxonomic position is clarified. The morphology of L. pallipes on Fagus and L. longirostris on Quercus was confirmed to be the same, but different from L. roboris, and sexual morphs of L. pallipes and L. roboris are redescribed. The results of morphological analysis were confirmed with molecular markers, so L. longirostris (Mordvilko, 1909) was synonymized with L. pallipes (Hartig, 1841), and the neotype of L. pallipes was designated. The effectiveness of both mitochondrial markers in barcoding and phylogenetic studies within Lachnus is also discussed.