The Aphid Genus Lachnus Burmeister, 1835 in Caucasus with Description of a New Species (Hemiptera, Aphididae, Lachninae)

The genus Lachnus Burmeister, 1835 (Hemiptera, Aphididae, Lachninae) comprises 35 valid species of medium to large-sized aphids associated with trees belonging to various plant families, mostly Fagaceae. This work reviews Lachnus species recorded so far in Transcaucasia (Georgia, Armenia, and Azerbaijan) and includes the description of a new species, Lachnus caucasicus sp. nov., belonging to the “pallipes” group, based on apterous and alate viviparous females collected in Georgia. The new species is compared with other congeners, focusing especially on morphological differences from L. pallipes (Hartig, 1841). Furthermore, updated keys to the species of the “pallipes” group, as well as to Caucasian Lachnus species and world Quercus-feeding species of Lachnus, are provided.