This leech is hosted by the Eurasian Burbot (Lota lota lota). This fish subspecies occurs east to the Mackenzie Delta but the North American Burbot (Lota lota maculosa) occurs north to Great Slave Lake. Very little mixing has been reported in the Mackenzie River Basin. It seems possible that the North American subspecies reached the basin from the unglaciated territory to the south (Missouri-Mississipian), whereas the mainly Eurasian subspecies occupies its unglaciated (Beringian) territory. In North America, the leech has thus far been reported only from the Mackenzie Delta. It could be a true disjunct (from Siberia) surviving in the relatively mild delta region, but lost from intervening territory as a result of Pleistocene climatic extinctions (Hovingh 2016, p. 158, 160). The fact that this leech was not found on Burbot in Aishihik Lake in unglaciated Yukon may be due to a preference for flowing water (Pronin 1979).