(Lecithasteridae, Digenea) in the White Sea: an unnoticed guest from the Pacific?

Morphological discrimination of species is problematic in many digenean taxa. Parasites of marine fish from the genus Lühe, 1901 are a good example of this. Our goal was to understand which species of infect fish in the White Sea, and reveal their life cycles. We collected specimens of maritae from nine fish species, analysed their morphology and sequenced 28S ribosomal DNA and internal transcribed spacer 2 (ITS2). Contrary to previous accounts, all of them belong to a single species, Yamaguti, 1934, which was previously only recorded from the Pacific. Morphologically, our maritae specimens were highly variable, sharing characters of , Odhner, 1905 and (Rudolphi, 1802) Lühe, 1901. This variability did not correlate with the moderate differences in ITS2 among the specimens, and neither did the fish host species. Members of the subfamily Salmoninae appear to be the best suited definitive hosts, judging from the intensity rates. The intermediate hosts were also discovered: the first is (Gmelin, 1791) and the second are planktonic copepods. These lifecycle data from the White Sea are consistent with species identification and with the distribution of this species in the North Pacific. The geographical range of seems to be interrupted, and we discuss possible ways of expansion.