Haplotype networks for M. pseudopygmaeus, also including several samples of M. pygmaeus and M. similis, based on the fragment of the cox1 gene (800 bp). Circle sizes represent haplotype frequencies, hatch marks represent substitutions (if more than five, replaced with numbers). The asterisk marks the sample from L. arcana (belongs to “saxatilis” species complex). Haplotypes are colored according to parasite host species (a) and sampling location (b). The sampling locations in the Barents Sea: Dalniye Zelentsy (southwestern), Chosha Bay, Kanin Cape (southeastern); in the Pechora Sea: Dolgiy Island, Vaygach Island, Malyi Zincovyi Island, Gubistyi Island; in the White Sea: Levin Navolok Bay, Cape Kindo, Korovya Varakka Cliff; in the Sea of Okhotsk: Tyuleniy Island, Taygonos Cape, Nagaev Bay; in the Atlantic Ocean: Grindavik.