transect of Europe: patterns in the distribution of willow-feeding psyllids (Hemiptera: Psylloidea) from Greece to arctic Norway.

Psyllids are oligophagous phytophagous insects with many specialist willow ( spp.) feeding species in two genera ( and ). We examine the patterns of distribution and co-occurrence of willow-feeding species at 42 willow sites across Europe forming a transect from Greece (lat. 38.8 °N) to arctic Norway (lat. 70.6 °N). The transect and sites have been described in previous papers. A total of 1245 individual psyllids were examined from 23 species of willow over the transect, representing 17 willow-feeding species (11 and 6 ). Numerous species were very widely distributed, with two species, (Foerster, 1848) and (Zetterstedt, 1840), occurring from Greece to Finland. Other widespread species (Romania to Finland) were (Foerster, 1848) and (Foerster, 1848). The mean number of psyllid species per site was 2.4 (1.3 , 1.1 ).