Phylogenetic neighbor-joining analysis of a 1015 nucleotide fragment of the USUV NS5 gene (corresponding nucleotide positions 9072–10,088 of the SAAR-1776 strain, GenBank accession numberAY453412) detected in Culex pipiens pool in Croatia and representative USUV strains from mosquitoes (n = 36). GenBank accession numbers, countries of origins, isolation/detection years and mosquito species are indicated at the branches. Viruses from Croatia are marked in bold and red color. USUV genetic lineages suggested by Cadar et al. (2017) [38] are indicated on the right. Supporting (≥50%) bootstrap values of 1000 replicates are displayed at the nodes. Horizontal distances are proportional to genetic distance. Scale bar indicates nucleotide substitutions per site. The interrupted branches, indicated by double slashes, were shortened by 80% for better graphic representation.