| Anterior sucker1 | Absent | Present (first five segments) |
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| Chaetae (setae)1,2 (Table 3) | One type: similar for first five rows; angle of | Two types: broader for fourth and fifth |
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| flexion (hooks) ~90° | rows; angle of flexion ~150° (apart from |
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| | chaetae on segment 3) |
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| Crop and oesophagus2 | Not distinct from one another; crop undivided | Distinct from one another; crop divided |
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| Segments (somites)2 | 31 | 31 |
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| Ovisac shape2 | Twisted; 3.0–4.5 segments long; extends poster- | Elongated with ‘horseshoe-shaped’ ends; |
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| iorly to ½ of testisac | 7.5–9.0 segments long; extends poster- |
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| | iorly to full length of testisac or farther |
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| Testisacs2 | Posterior end rounded; seven segments long | Posterior end curved; eight segments long |
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| Distance between male and | Three complete annuli; however, male and female | Three complete annuli; however, male |
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| female gonopores5 | gonopores can be slightly anterior or posterior | and female gonopores can be slightly |
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| to their respective furrows | anterior or posterior to their respective |
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| | furrows |
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| Geography3,4 (Fig. 2) | Broadly across northern Eurasia and Alaska | Russian Far East |
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| Free-living status2,5 | Only to reproduce (sometime between September | Commonly observed in this state |
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| and April) | |
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| Host records2,3,4,6,* | Salmonidae: Brachymystax lenok (Pallas, | Salmonidae: Oncorhynchus mykiss |
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| (parasitic feeding mode) | 1773); Coregonus autumnalis (Pallas, 1776); | (Walbaum, 1792); Salvelinus |
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| Coregonus lavaretus (Linnaeus, 1758); | leucomaenis (Pallas, 1814); Salvelinus |
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| Coregonus muksun (Pallas, 1814); Coregonus | malma ‡ (Walbaum, 1792); and |
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| nasus (Pallas, 1776); Coregonus peled (Gmelin, | Salvelinus taranetzi Kaganowsky, 1955 |
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| 1789); Coregonus pidschian (Gmelin, 1789); | Gasterosteidae: Gasterosteus aculeatus |
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| Coregonus sardinella Valenciennes, 1848; | Linnaeus, 1758 |
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| Coregonus tugun (Pallas, 1814); Esox lucius | |
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| Linnaeus, 1758; Hucho taimen (Pallas, 1773); | |
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| Prosopium cylindraceum (Pennant, 1784); | |
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| Salmo salar Linnaeus, 1758; Salmo trutta | |
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| Linnaeus, 1758; Salvelinus alpinus (Lin- | |
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| naeus, 1758); Salvelinus neiva Taranetz, 1933; | |
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| Stenodus leucichthys (Güldenstädt, 1772); | |
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| Stenodus nelma (Pallas, 1773); Thymallus | |
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| arcticus (Pallas, 1776); Thymallus baicalensis | |
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| Dybowski, 1874; Thymallus pallasii Valenci- | |
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| ennes, 1848; and Thymallus thymallus (Lin- | |
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| naeus, 1758) | |
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| Lotidae: Lota lota (Linnaeus, 1758) | |
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| Alternative prey species2 | None known | Odonata and Chironomidae larvae |
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| (predatory feeding mode) | | |
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| COI distance within species7 | Average = 0.42%; range = 0.00–1.52% (please | 0.11% |
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| note that this does not include Alaskan sam- | |
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| ples) | |
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| COI distance between species7 | Average = 13.20%; range = 13.17–13.49% | |
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