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Research Article
Host records and geographical distribution of Corynosoma magdaleni, C. semerme and C. strumosum (Acanthocephala: Polymorphidae)
expand article infoSonja Leidenberger, Sven Boström§, Matthew Thomas Wayland|
‡ School of Bioscience, Department of Biology and Bioinformatics, University of Skövde, Skövde, Sweden
§ Swedish Museum of Natural History, Department of Zoology, Stockholm, Sweden
| University of Cambridge, Cambridge, United Kingdom
Open Access

Abstract

A literature survey was conducted to investigate the host and geographical distribution patterns of three Corynosoma species (Acanthocephala: Polymorphidae), viz. C. magdaleni, C. semerme and C. strumosum. All three species appear to be restricted to the Northern Hemisphere. Occurrence records of C. magdaleni are limited to the Northern Atlantic coasts, while C. semerme has a circumpolar distribution. The geographical range of Corynosoma strumosum encompasses the distributions of the other two species, but also extends into warmer southern regions. Some Corynosoma populations are living with their definitive hosts in very isolated locations, such as in the brackish Baltic Sea or different freshwater lakes (e.g. Lake Saimaa). All three species have a heteroxenous life cycle, comprising a peracaridan intermediate host, a fish paratenic host and a mammalian definitive host. Occasionally, an acanthocephalan may enter an accidental host, from which it is unable to complete its life cycle. The host records reported here are categorised by type, i.e. intermediate, paratenic, definitive or accidental. While most of the definitive hosts are shared amongst the three Corynosoma species, C. strumosum showed the broadest range of paratenic hosts, which reflects its more extensive geographical distribution. One aim of this study and extensive literature summary is to guide future sampling efforts and therewith contribute to throw more light on the on-going species and morphotype discussion for this interesting parasite species.

Keywords

Acanthocephala, Corynosoma, host record, life cycle, Northern Hemisphere, seal and zoogeography

Introduction

The genus Corynosoma comprises 43 marine species (Amin 2013), that infect mammals and piscivorous birds. Aznar et al. (2006) showed that the original concept of Corynosoma was not a monophyletic genus. Phylogenetic analysis revealed that the marine Corynosoma species were more closely related to the genus Andracantha Schmidt, 1975 than to the species living in freshwater habitats. Aznar et al. (2006) erected the genus Pseudocorynosoma Aznar, Pérez-Ponce de León and Raga, 2006 for the freshwater species. Recent phylogenetic analysis based on ribosomal ITS1-5.8S-ITS2 and COI sequences showed that Corynosoma spp., hosted by Pinnipedia and marine Mustelidae formed a monophyletic group (Waindok et al. 2018).

The systematics of Corynosoma species from seals in northern Europe have recently been investigated using both molecular markers (Waindok et al. 2018) and morphology (Leidenberger et al. 2019). These studies have highlighted the limitations of using traditional morphological characters alone for diagnosing species. To determine the true species diversity in this genus, tandem morphological and molecular studies will be required. To guide future sampling efforts, we have conducted a comprehensive literature survey of the host and geographical distribution of three commonly encountered taxa: C. magdaleni Montreuil, 1958, C. semerme (Forssell, 1904) Lühe, 1911 and C. strumosum (Rudolphi, 1802) Lühe, 1904.

Material and methods

Host and geographical records

Host and geographical records for the three acanthocephalan taxa were collected from literature. Manual searches were conducted using Pubmed, Web of Science and Google Scholar. Additionally, we used the R (R Core Team 2019) package helminthR (Dallas 2016) to extract records from the Host-Parasite Database of The Natural History Museum in London (Gibson et al. 2005). Geographical records for each Corynosoma species were summarised by MEOW ecoregions (Spalding et al. 2007) and then plotted as a distribution map using the meow R-package (Byrnes 2016).

Nomenclature

For species names, we followed the nomenclature given by the Catalogue of Life (2019 Annual Checklist: Roskov et al. 2019) and WoRMS (WoRMS Editorial Board 2019).

The term accidental host was used here for a host, where the parasite usually is not found, because the host is not suitable for the parasite's development. This can mean that the accidental host also becomes a dead-end, because the life cycle of the parasite is blocked (e.g. no observed gravid female and/or mature individuals) and the parasite does not reach its definitive host. Since in many literature references, this detailed information was not given, we used the term accidental host as generic term for all of the dead-end/accidental/incidental host records we found.

Results and discussion

Zoogeography

Our literature survey on the zoogeography showed that the three species of Corynosoma (C. magdaleni, C. semerme and C. strumosum) and their definitive hosts are restricted to the Northern Hemisphere (Figs 1, 2, 3). The relatively few records for C. magdaleni suggest that this taxon is restricted to the North Sea, Baltic Sea and northwest Atlantic. By contrast, C. semerme has a circumpolar distribution, having been reported from the Arctic Ocean, north Atlantic and north Pacific (e.g. Popov and Fortunato 1987, Kaimoto et al. 2018, Waindok et al. 2018) (Fig. 2). The geographical range of C. strumosum encompasses the distributions of the other two taxa, but also extends into more southern regions, such as the Mediterranean Sea and coast of California (Fig. 3).

Figure 1.  

Geographical distribution of Corynosoma magdaleni.

Figure 2.  

Geographical distribution of Corynosoma semerme.

Figure 3.  

Geographical distribution of Corynosoma strumosum.

In most of the Baltic Sea studies, C. semerme was the species most commonly found in seals, followed by C. magdaleni and only rare infections were found for C. strumosum (Nickol et al. 2002, Sinisalo and Valtonen 2003, Leidenberger and Bäcklin 2008, Waindok et al. 2018). Co-infections have been observed (Nickol et al. 2002, Leidenberger and Bäcklin 2008, Leidenberger et al. 2019), most commonly involving C. semerme and C. magdaleni (Sinisalo and Valtonen 2003, Leidenberger and Bäcklin 2008, Waindok et al. 2018). Interestingly, land-locked seal species show no mixed infections, but only single infections, for example, Phoca hispida saimensis in Lake Saimaa only by C. magdaleni (Sinisalo and Valtonen 2003) and Pusa caspica in the Caspian Sea only by C. strumosum (Amin et al. 2011). García-Varela et al. (2005) concluded that the Corynosoma species found in the Caspian Sea is C. caspicum and not C. strumosum. Indeed, C. strumosum from the land-locked Caspian seal recorded by Amin et al. 2011 was characterised with proboscis hooks and trunk spines distinct from other Northern European morphological descriptions (Nickol et al. 2002, Waindok et al. 2018, Leidenberger et al. 2019), suggesting that they may not be conspecific. Surprisingly, Corynosoma caspicum Golvan and Mokhayer, 1973, described based on immature specimens from sturgeons in Caspian Sea (Golvan and Mokhayer 1973) and often found in three-spined stickleback (Gasterosteus aculeatus) (Niksirat et al. 2006), has not yet been reported in Pusa caspica or another definitive host. Waindok et al. (2018) described some individuals of C. strumosum from the German North and Baltic Seas with different proboscis morphology, similar to those described by Amin et al. (2011) and stated this as C. magaleni isolate Pv1NS instead. Additionally, they found a cryptic species refered to as "Candidatus Corynosoma nortmeri sp. nov."' Waindok et al. (2018) in the European study area.

The extent of the geographical and host ranges of the three taxa correlates with the year of their description. Corynosoma strumosum was the first species of the genus to be described (Rudolphi 1802) and has, by far, the broadest geographical and host distributions. Corynosoma semerme, described by Forssell (1904), appears to have a slightly more limited geographical range and far fewer paratenic host records. Relatively few hosts have been reported for C. magdaleni, described by Montreuil (1958) and its geographical range appears to be restricted to the northern Atlantic, in contrast to the circumpolar distributions of the other two species. Up until its description in 1958, specimens of C. magdaleni were almost certainly assigned to the morphologically similar C. strumosum. The potential bias resulting from taxon age should be kept in mind when comparing the reported host and geographical distributions of the three taxa (Fig. 3).

Overview of the life cycle

The heteroxenous life cycle of Corynosoma species involves a peracaridan intermediate host, a paratenic host (fish) and a mammalian definitive host. While there are numerous studies on C. semerme and C. strumosum (Tables 3, 4, 5, 6, 7, 8), there have been few studies on C. magdaleni, besides its original description by Montreuil 1958 (Tables 1, 2). The intermediate host of C. magdaleni is unknown. Lake Saimaa may be a good location to search for the intermediate host of C. magdaleni, because the other Corynosoma species appear to be absent from this land-locked waterbody (Sinisalo and Valtonen 2003, Sinisalo et al. 2003). A total of five species of paratenic host (all Actinopterygii) have been reported for C. magdaleni; three from Canada and two from the Baltic Sea (Table 1). In Canada, only C. magdaleni is reported together with C. wegeneri Heinze, 1934. In the definitive hosts (Table 2), the species seems to prefer the last part of the small intestine (ileum) and the colon. Corynosoma semerme has been reported from the whole intestine, but is typically found at a higher density in the large intestine, especially the cecum and rectum (Nickol et al. 2002, Leidenberger and Bäcklin 2008), where C. strumosum and C. magdaleni are not generally observed. Microhabitat segregation might facilitate reproductive isolation of the three species, especially in mixed infections that are often observed in seals from the Baltic Sea (Nickol et al. 2002, Sinisalo and Valtonen 2003, Leidenberger and Bäcklin 2008), but less commonly in the North Sea (Waindok et al. 2018). While the three Corynosoma species share most of their definitive hosts, they show some differences in their paratenic hosts. We found that C. strumosum shares three paratenic hosts with both other species, none with C. magdaleni only, but > 20 paratenic hosts are shared with C. semerme. More than 80 paratenic hosts were described for C. strumosum and these are, up to now, not reported from any of the other two species (Tables 1, 4, 6).

Paratenic host records for Corynosoma magdaleni. All Actinopterygii.

Host order Host family Host species Host vernacular name Geographical locality Reference(s)
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Gymnocephalus cernuus) ruffe Baltic Sea, North-eastern Bothnian Bay Valtonen et al. 2001
Pleuronectiformes Pleuronectidae Hippoglossus hippoglossus (Linnaeus, 1758) Atlantic halibut Atlantic, Canada Arai 1989
Pleuronectiformes Pleuronectidae Hippoglossus hippoglossus (Linnaeus, 1758) Atlantic halibut Magdalen Islands region of the Gulf of St. Lawrence Montreuil 1958
Salmoniformes Salmonidae Salvelinus fontinalis (Mitchill, 1814) brook charr Tabusintac River, New Brunswick Frimeth 1987
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) fourhorn sculpin Baltic Sea, Bothnian Bay Sinisalo and Valtonen 2003
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) shorthorn sculpin Atlantic, Canada Arai 1989
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) shorthorn sculpin Magdalen Islands region of the Gulf of St. Lawrence Montreuil 1958

Definitive host records for Corynosoma magdaleni. All members of the family Phocidae, order Carnivora.

Host order Host family Host species Host vernacular name Geographical locality Reference
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea Waindok et al. 2018
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Baltic Proper, Bothnian Sea, Bothnian Bay, Sweden Leidenberger and Bäcklin 2008
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Finland, Gulf of Bothnia, Åland Island Nickol et al. 2002
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Sweden Leidenberger et al. 2019
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Eastern Canada Montreuil 1958
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Eastern Canada Montreuil 1958
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal North Sea, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 (as Phoca vitulina concolor De Kay, 1842) harbour seal Eastern Canada Montreuil 1958
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea Leidenberger et al. 2019
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Germany, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay Valtonen et al. 2004
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Gulf of Finland Delyamure et al. 1980
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal European Arctic Treshchev 1982* citet by Raga 1992
Carnivora Phocidae Pusa hispida saimensis Nordquist, 1899 Saimaa ringed seal Lake Saimaa, Finland Sinisalo et al. 2004, Aznar et al. 2006, García-Varela et al. 2011

Definitive hosts of Corynosoma semerme. *Source not viewed, ^Found in Host-Parasite Database NHM London without further reference details.

Host order Host family Host species Host vernacular name Geographical locality Reference
Artiodactyla Monodontidae Delphinapterus leucas (Pallas, 1776) Beluga, Beluga whale, white whale Bristol Bay, Alaska, Bering Sea

Neiland 1962,

Measures et al. 1995

Carnivora Odobenidae Odobenus rosmarus (Linnaeus, 1758) walrus Arctic Ocean, Northern Atlantic Delyamure 1961, von Sprehn 1966 cited by Raga 1992
Carnivora Otariidae Callorhinus ursinus (Linnaeus, 1758) Northern fur seal Alaska, Bering Sea, St. Paul Island Kuzmina et al. 2012
Carnivora Otariidae Callorhinus ursinus (Linnaeus, 1758) (as Callorhinus alascanus) Northern fur seal North America Van Cleave 1953
Carnivora Phocidae Cystophora cristata (Erxleben, 1777) hooded seal European Arctic

Delyamure 1961*, Treshchev 1982* cited by Raga 1992

Carnivora Phocidae Erignathus barbatus (Erxleben, 1777) bearded seal North America Van Cleave 1953
Carnivora Phocidae

Erignathus barbatus

(Erxleben, 1777)

bearded seal White Sea Popova et al. 1975* cited by Raga 1992
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Arctic Ocean, Northern Atlantic, European Arctic von Sprehn 1966* cited by Raga 1992
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Germany Lühe 1911
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Germany Aznar et al. 2006
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Finland, Gulf of Bothnia, Åland Island Nickol et al. 2002
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Baltic Proper, Bothnian Sea, Bothnian Bay, Sweden Leidenberger and Bäcklin 2008
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Germany, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Histriophoca fasciata (Zimmerman, 1783) (as Phoca fasciata) ribbon seal Bering Sea, Alaska Rausch et al. 1990
Carnivora Phocidae Histriophoca fasciata (Zimmerman, 1783) (as Phoca fasciata) ribbon seal Arctic Ocean, Bering Sea Shults and Frost 1988
Carnivora Phocidae Histriophoca fasciata (Zimmerman, 1783) (as Phoca fasciata) ribbon seal Sea of Okhotsk Shults and Frost 1988
Carnivora Phocidae Pagophilus groenlandicus (Erxleben, 1777) (as Phoca groenlandica) harp seal, Greenland seal Arctic Ocean, Northern Atlantic, European Arctic von Sprehn 1966* cited by Raga 1992
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal, larga seal Sea of Okhotsk Sasaki et al. 2019
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal, larga seal Russia Aznar et al. 2006
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal, larga seal Bering Sea, Alaska Rausch et al. 1990
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal, larga seal Arctic Ocean, Bering Sea [On the helminthofauna of largi and harbour seals.]^
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal, larga seal Sea of Okhotsk [On the helminthofauna of largi and harbour seals.]^
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Germany Lühe 1911
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Sweden Lundström 1942
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal North Sea, Germany, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Arctic Ocean, Northern Atlantic, European Arctic von Sprehn 1966* cited by Raga 1992
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Alaska, Bering Sea, St. Paul Island Kuzmina et al. 2012
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Germany Lühe 1911
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Helle and Valtonen 1981
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Valtonen and Helle 1988
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Valtonen et al. 2004
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal North America Van Cleave 1953
Carnivora Phocidae Pusa hispida (Schreber, 1775) (as Phoca foetida) ringed seal Baltic Sea, Sweden, Östra Rönnskär Forssell 1904
Carnivora Phocidae Pusa hispida (Schreber, 1775) (as Phoca foetida) ringed seal Baltic Sea, Finland, Tvärminne Forssell 1905

Paratenic hosts of Corynosoma semerme; all Actinopterygii. *Source not viewed.

Host order Host family Host species Host vernacular name Geographical locality Reference
Acipenseriformes Acipenseridae Acipenser sturio Linnaeus, 1758 sturgeon USSR (CIS) Shulman 1954*
Acipenseriformes Acipenseridae Acipenser sturio Linnaeus, 1758 sturgeon USSR (CIS) Shulman 1954*
Anguilliformes Anguillidae Anguilla anguilla (Linnaeus, 1758) European eel Sweden Lundström 1942
Anguilliformes Anguillidae Anguilla anguilla (Linnaeus, 1758) European eel Europe Van Cleave 1953
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 herring Sweden Lundström 1942
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 (as Clupea harengus membras) herring Baltic Sea, Finland, Tvärminne Forssell 1904
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 (as Clupea harengus membras) herring Baltic Sea, Finland, Tvärminne Forssell 1905
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 (as Clupea harengus membras) herring Germany Lühe 1911
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 (as Clupea harengus membras) herring Europe Van Cleave 1953
Cypriniformes Cyprinidae Blicca bjoerkna (Linnaeus, 1758) white bream Sweden Lundström 1942
Cypriniformes Cyprinidae Blicca bjoerkna (Linnaeus, 1758) white bream Europe Van Cleave 1953
Cypriniformes Cyprinidae Pelecus cultratus (Linnaeus, 1758) ziege Finno-Karelian ASSR Rumyantsev and Ieshko 1997*
Esociformes Esocidae Esox lucius Linnaeus, 1758 pike Baltic Sea, Finland, Tvärminne Forssell 1905
Gadiformes Gadidae Boreogadus saida (Lepechin, 1774) polar cod Arctic Ocean, USSR zone, Pechora Sea Karasev and Mitenev 1993*
Gadiformes Gadidae Gadus morhua Linnaeus, 1758 cod Baltic Sea, Finland, Tvärminne Forssell 1905
Gadiformes Gadidae Gadus morhua Linnaeus, 1758 (as Gadus callarias) cod Sweden Lundström 1942
Gadiformes Gadidae Gadus morhua Linnaeus, 1758 (as Gadus callarias) cod Europe Van Cleave 1953
Gadiformes Lotidae Enchelyopus cimbrius (Linnaeus, 1766) (as Onos cimbrius) fourbeard rockling Europe Van Cleave 1953
Gadiformes Lotidae Lota lota (Linnaeus, 1758) burbot Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Sweden Lundström 1942
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Europe Van Cleave 1953
Gadiformes Lotidae Lota lota (Linnaeus, 1758) burbot Tuluksak, Bering Sea, Alaska Rausch et al. 1990
Gasterosteiformes Gasterosteidae Gasterosteus aculeatus Linnaeus, 1758 three-spined stickleback Sweden Lundström 1942
Lophiiformes Lophiidae Lophius piscatorius Linnaeus, 1758 angler Sweden Lundström 1942
Osmeriformes Osmeridae

Osmerus dentex

Steindachner and Kner, 1870

Pacific rainbow smelt Japan Sasaki et al. 2019
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Baltic Sea, Finland, Tvärminne Forssell 1904
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Baltic Sea, Finland, Tvärminne Forssell 1905
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Germany Lühe 1911
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Sweden Lundström 1942
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Europe Van Cleave 1953
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Perciformes Labridae Ctenolabrus rupestris (Linnaeus, 1758) Atlantic herring southern Norway, Flødevigen, Karlsbakk et al. 1996
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Acerina cernua) ruffe Baltic Sea, Finland, Tvärminne Forssell 1905
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Acerina cernua) ruffe Germany Lühe 1911
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Acerina cernua) ruffe Sweden Lundström 1942
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Acerina cernua) ruffe Europe Van Cleave 1953
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Gymnocephalus cernuus) ruffe Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Baltic Sea, Finland, Tvärminne Forssell 1905
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Sweden Lundström 1942
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Europe Van Cleave 1953
Perciformes Percidae Sander lucioperca (Linnaeus, 1758) (as Stizostedion lucioperca) zanda, pike-perch Finno-Karelian ASSR Rumyantsev and Ieshko 1997*
Perciformes Zoarcidae Lycodes raridens Taranetz & Andriashev, 1937 marbled eelpout Arctic Ocean, Bering Sea Shults and Frost 1988
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Sweden Lundström 1942
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Europe Van Cleave 1953
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Baltic Sea, Estonia, Riga Bay Vismanis et al. 1980*
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Baltic Sea, Germany, Lübecker Bay Zander 1991
Pleuronectiformes Pleuronectidae Hippoglossoides platessoides (Fabricius, 1780) (as Hippoglossoides platessoides limandoides) American plaice Arctic Ocean, Greenland/Icelandic Zone, Icelandic coast Olafsdottir 1999
Pleuronectiformes Pleuronectidae Limanda limanda (Linnaeus, 1758) (as Pleuronectes limanda) common dab Sweden Lundström 1942
Pleuronectiformes Pleuronectidae Limanda limanda (Linnaeus, 1758) (as Pleuronectes limanda) common dab Europe Van Cleave 1953
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Baltic Sea, Finland, Tvärminne Forssell 1905
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Germany Lühe 1911
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Sweden Lundström 1942
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Sweden Van Cleave 1953
Pleuronectiformes Pleuronectidae Pleuronectes platessa Linnaeus, 1758 European plaice Europe Van Cleave 1953
Pleuronectiformes Pleuronectidae Pseudopleuronectes americanus Walbaum, 1792 winter flounder Atlantic, Canada Arai 1989
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) turbot Baltic Sea, Finland, Tvärminne Forssell 1904
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) turbot Baltic Sea, Finland, Tvärminne Forssell 1905
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) turbot Germany Lühe 1911
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) turbot Sweden Lundström 1942
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) turbot Europe Van Cleave 1953
Salmoniformes Salmonidae Coregonus albula (Linnaeus, 1758) European cisco Sweden Lundström 1942
Salmoniformes Salmonidae Coregonus albula (Linnaeus, 1758) European cisco Europe Van Cleave 1953
Salmoniformes Salmonidae Coregonus fera Jurine, 1825 true fera Europe Van Cleave 1953
Salmoniformes Salmonidae Salmo salar Linnaeus, 1758 salmon European USSR (CIS) Rumyantsev et al. 1998*
Salmoniformes Salmonidae Salmo trutta Linnaeus, 1758 brown trout, sea trout European USSR (CIS) Rumyantsev et al. 1998*
Salmoniformes Salmonidae Thymallus thymallus (Linnaeus, 1758) grayling Europe Rumyantsev et al. 1999*
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) fourhorn sculpin Baltic Sea, Bothnian Bay Sinisalo and Valtonen 2003
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Baltic Sea, Finland, Tvärminne Forssell 1904
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Baltic Sea, Finland, Tvärminne Forssell 1905
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Germany Lühe 1911
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Sweden Lundström 1942
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Europe Van Cleave 1953
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) shorthorn sculpin Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) shorthorn sculpin Baltic Sea, North-eastern Bothnian Bay Valtonen et al. 2001
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) shorthorn sculpin Sweden Lundström 1942
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) shorthorn sculpin Baltic Sea, Finland, Tvärminne Forssell 1905
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) shorthorn sculpin Europe Van Cleave 1953
Scorpaeniformes Cyclopteridae Cyclopterus lumpus Linnaeus, 1758 goldsinny wrasse Sweden Lundström 1942
Scorpaeniformes Cyclopteridae Cyclopterus lumpus Linnaeus, 1758 goldsinny wrasse Europe Van Cleave 1953
Scorpaeniformes Psychrolutidae Dasycottus setiger Bean, 1890 spinyhead sculpin Arctic Ocean, Bering Sea Shults and Frost 1988

Definitive hosts of Corynosoma strumosum. *Source not viewed. ^Found in Host-Parasite Database NHM London without further reference details.

Host

order

Host family Host species Host vernacular name Geographical locality Reference
Artiodactyla Monodontidae Delphinapterus leucas (Pallas, 1776) Beluga, Beluga whale, white whale Bristol Bay, Alaska, Barent Sea, Sea of Okhotsk, North Pacific Ocean, Arctic

Krotov and Delyamure 1952*, Delyamure and Kleinenberg 1958*, Neiland 1962, Yablokov et al. 1972* all cited by

Measures et al. 1995

Carnivora Odobenidae

Odobenus rosmarus

(Linnaeus, 1758)

walrus no area specified Dailey 1975, Raga 1992
Carnivora Otariidae Callorhinus ursinus (Linnaeus, 1758) Northern fur seal Alaska, Bering Sea, St. Paul Island

Ionita et al. 2008, Kuzmina et al. 2012

Carnivora Otariidae Zalophus californianus (Lesson, 1828) California sea lion California Van Cleave 1953
Carnivora Phocidae Cystophora cristata (Erxleben, 1777) hooded seal Europe Van Cleave 1953
Carnivora Phocidae Erignathus barbatus (Erxleben, 1777) bearded seal Alaska, Arctic Van Cleave 1953
Carnivora Phocidae Erignathus barbatus (Erxleben, 1777) bearded seal Barent Sea, Sea of Okhotsk, Chukchi seas, Eastern Siberian Sea Popov and Fortunato 1987
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Germany Lühe 1911
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Holland, Germany Aznar et al. 2006
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Atlantic coast, Ireland O'Neill and Whelan 2002
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Finland, Gulf of Bothnia, Åland Island Nickol et al. 2002
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Baltic Sea, Baltic Proper, Bothnian Sea, Bothnian Bay, Sweden Leidenberger and Bäcklin 2008
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal North Sea, Germany, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Arctic Ocean, Northern Atlantic, European Arctic Delyamure 1961*, von Sprehn 1966* cited by Raga 1992
Carnivora Phocidae Halichoerus grypus (Fabricius, 1791) grey seal Alaska, Arctic Van Cleave 1953
Carnivora Phocidae Histriophoca fasciata (Zimmermann, 1783) ribbon seal Barent Sea, Sea of Okhotsk, Chukchi seas, Eastern Siberian Sea Popov and Fortunato 1987
Carnivora Phocidae Histriophoca fasciata (Zimmermann, 1783) (as Phoca fasciata) ribbon seal Bering Sea, Alaska Rausch et al. 1990
Carnivora Phocidae Histriophoca fasciata (Zimmermann, 1783) (as Phoca fasciata) ribbon seal Bering Sea Shults and Frost 1988
Carnivora Phocidae Pagophilus groenlandicus (Erxleben, 1777) harp seal Greenland Van Cleave 1953
Carnivora Phocidae Pagophilus groenlandicus (Erxleben, 1777) (as Phoca groenlandica) harp seal Germany Lühe 1911
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal Sea of Okhotsk, Japan Sea Sasaki et al. 2019
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal Bering Sea, Alaska Rausch et al. 1990
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal Bering Sea [On the helminthofauna of largi and harbour seals.]^
Carnivora Phocidae Phoca largha Pallas, 1811 Larga seal, spotted seal Barent Sea, Sea of Okhotsk, Chukchi seas, Eastern Siberian Sea Popov and Fortunato 1987
Carnivora Phocidae Phoca largha Pallas, 1811 Larga seal, spotted seal Russia: Anadyr Gulf Aznar et al. 2006
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal no area specified [On the helminthofauna of largi and harbour seals.]^
Carnivora Phocidae Phoca largha Pallas, 1811 spotted seal Japan, Hokkaido, Nemuro Peninsula Nakaoka et al. 1986*
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Baltic Sea Mühling 1989
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Germany Rudolphi 1802
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Germany Lühe 1911
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Sweden Lundström 1942
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Baltic Sea and North Sea, Germany, Schleswig-Holstein Waindok et al. 2018
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Alaska, Bering Sea, St. Paul Island Kuzmina et al. 2012
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Alaska, Arctic Van Cleave 1953
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal USA, California, Monterey Bay García-Varela et al. 2011
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 harbour seal Pacific Sasaki et al. 2019
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 (as Phoca vitulina stejnegeri J.A.Allen, 1902) Kuril harbour seal Japan, Hokkaido, Erimo Cape Kaimoto et al. 2018
Carnivora Phocidae Phoca vitulina Linnaeus, 1758 (as Phoca vitulina stejnegeri J.A.Allen, 1902) Kuril harbour seal Japan, Hokkaido, Nemuro Peninsula Nakaoka et al. 1986*
Carnivora Phocidae Phoca vitulina richardii (Gray, 1864) Californian harbour seal California Van Cleave 1953
Carnivora Phocidae Phoca vitulina richardii (Gray, 1864) Pacific harbor seal Washington, Northern Pacific Dailey and Fallace 1989
Carnivora Phocidae Pusa caspica (Gmelin, 1788) Caspian seal Iran, Mazandaran Province, Ramsar City Amin et al. 2011
Carnivora Phocidae

Pusa caspica,

(Gmelin, 1788)

(as Phoca caspica Gmelin, 1788)

Caspian seal Caspian Sea Kurochkin 1975* cited by Raga 1992
Carnivora Phocidae Pusa hispida saimensis (Nordquist, 1899) Saimaa ringed seal Lake Saimaa, Finland Valtonen and Helle 1988
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Germany Lühe 1911
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Sweden Lundström 1942
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Helle and Valtonen 1981
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Valtonen and Helle 1988
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Bothnian Bay, Finland Valtonen et al. 2004
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Baltic Sea, Sweden Leidenberger et al. 2019
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Alaska, Arctic Van Cleave 1953
Carnivora Phocidae Pusa hispida (Schreber, 1775) ringed seal Barent Sea, Sea of Okhotsk, Chukchi seas, Eastern Siberian Sea Popov and Fortunato 1987
Carnivora Phocidae Pusa hispida (Schreber, 1775) (as Phoca foetida) ringed seal Baltic Sea, Finland, Tvärminne Forssell 1904
Carnivora Phocidae Pusa hispida (Schreber, 1775) (as Phoca foetida) ringed seal Baltic Sea, Finland, Tvärminne Forssell 1905
Cetartiodactyla Phocoeridae

Phocoena phocoena

(Linnaeus, 1758)

harbour porpoise Pacific Sasaki et al. 2019
Cetartiodactyla Phocoeridae

Neophocaena phocaenoides

(G. Cuvier, 1829)

finless porpoise Pacific Sasaki et al. 2019

Paratenic host records for Corynosoma strumosum. *Source not viewed, NA: not available, ^Found in Host-Parasite Database NHM London without further reference details.

Host order Host family Host species Host vernacular name Geographical locality Reference
Acipenseriformes Acipenseridae Acipenser gueldenstaedti Brandt & Ratzeburg, 1833 Danube sturgeon Caspian Sea, southern part, Sefid-Rud River Sattari and Mokhayer 2005
Acipenseriformes Acipenseridae Acipenser persicus Borodin, 1897 (as Acipenser gueldenstaedti persicus natio kurensis) Persian sturgeon Georgia, River Kura Kurashvili et al. 1980*
Acipenseriformes Acipenseridae Acipenser stellatus Pallas, 1771 starry sturgeon Caspian Sea, southern part, Sefid-Rud River Sattari and Mokhayer 2005
Acipenseriformes Acipenseridae Acipenser transmontanus Richardson, 1836 white sturgeon British Columbia, Canada Arai 1989
Acipenseriformes Acipenseridae Huso huso (Linnaeus, 1758) beluga Caspian Sea, southern part, Sefid-Rud River Sattari and Mokhayer 2005
Anguilliformes Anguillidae Anguilla anguilla (Linnaeus, 1758) European eel Germany Lühe 1911
Anguilliformes Congridae Conger conger (Linnaeus, 1758) European conger Sweden Lundström 1942
Anguilliformes Congridae Conger conger (Linnaeus, 1758) European conger Europe Van Cleave 1953
Clupeiformes Clupeidae Alosa braschnikowi (Borodin, 1904) (as Alosa brashnikovi grimmi) Caspian marine shad Caspian Sea Ibragimov and Vetchanin 1988*
Clupeiformes Clupeidae Alosa braschnikowi (Borodin, 1904) (as Alosa brashnikovi kisselewitschi) Caspian marine shad Caspian Sea Ibragimov and Vetchanin 1988*
Clupeiformes Clupeidae Alosa kessleri (Grimm, 1887) (as Alosa kessleri volgensis) Caspian anadromous shad Caspian Sea Izyumova 1977*
Clupeiformes Clupeidae Alosa kessleri (Grimm, 1887) (as Alosa kessleri volgensis) Caspian anadromous shad USSR (CIS) Izyumova 1977*
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 herring Sweden Lundström 1942
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 herring Europe Van Cleave 1953
Clupeiformes Clupeidae Clupea harengus Linnaeus, 1758 (as Clupea harengus membras) herring Baltic Sea, Finland, Tvärminne Forssell 1905
Clupeiformes Clupeidae Clupea pallasii Valenciennes, 1847 Pacific herring Pacific ocean, Sea of Okhotsk Sasaki et al. 2019
Clupeiformes Clupeidae Clupea pallasii pallasii Valenciennes, 1847 (as Clupea harengus pallasii) Pacific herring Pacific ocean, Canada Arai 1989
Clupeiformes Clupeidae Clupeonella caspia Svetovidov, 1941 (as Clupeonella delicatula caspia) Caspian tyulka Caspian Sea Ibragimov 1988*
Clupeiformes Clupeidae Clupeonella cultriventris (Nordmann, 1840) (as Clupea cultriventris) Black Sea sprat Caspian Sea Shamsi et al. 1998*
Clupeiformes Clupeidae Clupeonella grimmi Kessler, 1877 Caspian sprat, big-eyed kilka Capian Sea, southern part Habibi and Shamsi 2018
Cypriniformes Cyprinidae Abramis brama (Linnaeus, 1758) freshwater bream Georgia, River Kura Kurashvili et al. 1980*
Cypriniformes Cyprinidae Alburnus chalcoides (Güldenstädt, 1772) (as Chalcalburnus chalcoides) shemaya Georgia, River Kura (USSR) Kurashvili et al. 1980*
Cypriniformes Cyprinidae Alburnus chalcoides (Güldenstädt, 1772) (as Chalcalburnus chalcoides) shemaya USSR (CIS) Izyumova 1977*
Cypriniformes Cyprinidae Barbus barbus (Linnaeus, 1758) barbel USSR (CIS) Izyumova 1977*
Cypriniformes Cyprinidae Barbus brachycephalus caspius Berg, 1914 Caspian barbel River Kura (USSR) Kurashvili et al. 1980*
Cypriniformes Cyprinidae Carassius carassius (Linnaeus, 1758) Crucian carp Azerbaijan On the study of helminths of the crucian carp in Azerbaijan fish farms.
Cypriniformes Cyprinidae Cyprinus carpio Linnaeus, 1758 common carp Georgia, River Kura (USSR) Kurashvili et al. 1980*
Cypriniformes Cyprinidae Leuciscus idus (Linnaeus, 1758) orfe, ide Finno-Karelian ASSR Rumyantsev and Ieshko 1997*
Cypriniformes Cyprinidae Pelecus cultratus (Linnaeus, 1758) sabrefish, razorfish, knife Finno-Karelian ASSR Rumyantsev and Ieshko 1997*
Cypriniformes Cyprinidae Rutilus frisii (Nordmann, 1840) (as Rutilus frisii kutum) Black Sea roach Georgia, River Kura (USSR) Kurashvili et al. 1980*
Cypriniformes Cyprinidae Rutilus rutilus (Linnaeus, 1758) (as Rutilus rutilus caspicus natio knipowitschia) roach Caspian Sea Ibragimov 1989*
Cypriniformes Cyprinidae Vimba vimba (Linnaeus, 1758) vimba bream Lithuania Rauckis 1988*
Esociformes Esocidae Esox lucius Linnaeus, 1758 pike Baltic Sea, Finland, Tvärminne Forssell 1905
Gadiformes Gadidae Boreogadus saida (Lepechin, 1774) Polar cod Arctic Ocean: USSR zone Karasev and Mitenev 1993*
Gadiformes Gadidae Eleginus gracilis (Tilesius, 1810) saffron cod Gertner Bay, Cape of Nyuklya near Magadan Skorobrechova and Nikishin 2014
Gadiformes Gadidae Eleginus gracilis (Tilesius, 1810) saffron cod Japan, Shikotan Island Zhukov 1960*
Gadiformes Gadidae Eleginus nawaga (Walbaum, 1792) (as Eleginus navaga) Arctic cod Arctic Ocean: USSR zone Karasev and Mitenev 1993*
Gadiformes Gadidae Gadus chalcogrammus Pallas, 1814 (as Theragra chalcogramma) Alaska pollock Bering Sea Shults and Frost 1988
Gadiformes Gadidae Gadus chalcogrammus Pallas, 1814 (as Theragra chalcogramma) Alaska pollock Bering Sea Avdeev and Avdeev 1998*
Gadiformes Gadidae Gadus chalcogrammus Pallas, 1814 (as Theragra chalcogramma) Alaska pollock Pacific ocean, Canada Arai 1989
Gadiformes Gadidae Gadus macrocephalus Tilesius, 1810 Pacific cod Pacific coast, USA and Canada Van Cleave 1953
Gadiformes Gadidae Gadus morhua Linnaeus, 1758 (as Gadus callarias) cod Sweden Lundström 1942
Gadiformes Gadidae Gadus morhua Linnaeus, 1758 (as Gadus callarias) cod Europe Van Cleave 1953
Gadiformes Gadidae Melanogrammus aeglefinus (Linnaeus, 1758) haddock Atlantic, Canada Arai 1989
Gadiformes Lotidae Lota lota (Linnaeus, 1758) burbot Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Baltic Sea, Finland, Tvärminne Forssell 1905
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Germany Lühe 1911
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Sweden Lundström 1942
Gadiformes Lotidae Lota lota (Linnaeus, 1758) (as Lota vulgaris) burbot Europe Van Cleave 1953
Gadiformes Merlucciidae Macruronus novaezelandiae (Hector, 1871) whiptail, tailed hake, Patagonian whiphake, New Zealand whiptail, blue hake, blue grenadier New Zealand coast Klimpel et al. 2001*
Gadiformes Merlucciidae Merluccius capensis Castelnau, 1861 whiting, stockfish, South African whiting, shallow-water Cape hake, shallow water hake, hake, Cape hake no area specified Parukhin 1989*
Gasterosteiformes Gasterosteidae Gasterosteus aculeatus Linnaeus, 1758 three-spined stickleback Sweden Lundström 1942
Gasterosteiformes Gasterosteidae Gasterosteus aculeatus Linnaeus, 1758 three-spined stickleback Europe Van Cleave 1953
Gasterosteiformes Gasterosteidae Gasterosteus aculeatus Linnaeus, 1758 three-spined stickleback Caspian Sea, southeast part, Gomishan Lagoon Niksirat et al. 2006
Lophiiformes Lophiidae Lophius piscatorius Linnaeus, 1758 angler Baltic Sea Mühling 1989
Lophiiformes Lophiidae Lophius piscatorius Linnaeus, 1758 angler Sweden Lundström 1942
Lophiiformes Lophiidae Lophius piscatorius Linnaeus, 1758 angler Europe Van Cleave 1953
Lophiiformes Lophiidae Lophius piscatorius Linnaeus, 1758 monkfish, angler-fish no area specified Parukhin 1989*
Ophidiiformes Ophidiidae Hoplobrotula gnathopus (Regan, 1921) false kinglip no area specified Parukhin 1989*
Osmeriformes Osmeridae Hypomesus japonicus (Brevoort, 1856) Japanese smelt Pacific ocean Sasaki et al. 2019
Osmeriformes Osmeridae Hypomesus japonicus (Brevoort, 1856) Japanese smelt Japan, Shikotan Island Zhukov 1960*
Osmeriformes Osmeridae Hypomesus japonicus (Brevoort, 1856) Japanese smelt Japan, Hokkaido, Erimo Cape Araki and Machida 1987*
Osmeriformes Osmeridae Hypomesus japonicus (Brevoort, 1856) (as Hypomesus preiosus japonicus) Japanese smelt Japan, Hokkaido Nagasawa et al. 1989*
Osmeriformes Osmeridae Hypomesus olidus (Pallas, 1814) pond smelt Nagaevo and Gertner Bay, Magadan, Russia, Sea of Okhotsk Skorobrechova and Nikishin 2011
Osmeriformes Osmeridae Hypomesus olidus (Pallas, 1814) pond smelt Japan, Shikotan Island Zhukov 1960*
Osmeriformes Osmeridae

Osmerus dentex

Steindachner and Kner, 1870

Pacific

rainbow

smelt

Japan, Sea of Okhotsk, Pacific ocean Sasaki et al. 2019
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Sweden Lundström 1942
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Europe Van Cleave 1953
Osmeriformes Osmeridae Osmerus eperlanus (Linnaeus, 1758) rainbow smelt Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Osmeriformes Osmeridae Osmerus mordax dentex Steindachner & Kner, 1870 rainbow smelt Nagaevo and Gertner Bay, Magadan, Russia, Sea of Okhotsk Skorobrechova and Nikishin 2011
Osmeriformes Osmeridae Spirinchus lanceolatus (Hikita, 1913) Sishamo smelt Japan Hokkaido, Mukawa River Fujita 1921*
Osmeriformes Osmeridae Spirinchus lanceolatus (Hikita, 1913) (as Osmerus lanceolatus) Shishamo, willow leaf fish Japan Van Cleave 1953
Perciformes Gobiidae Benthophilus stellatus (Sauvage, 1874) Stellate tadpole-goby Caspian Sea Ibragimov 1988*
Perciformes Gobiidae Gobius Linnaeus, 1758 goby Caspian Sea Ibragimov 1988*
Perciformes Gobiidae Neogobius fluviatilis (Pallas, 1814) (as Gobius fluviatilis) monkey goby Caspian Sea Ibragimov 1988*
Perciformes Gobiidae Neogobius fluviatilis (Pallas, 1814) (as Neogobius fluviatilis pallasi (Pallas, 1814) monkey goby Caspian Sea, south-eastern part Pazooki et al. 2011
Perciformes Gobiidae Neogobius melanostomus (Pallas, 1814) round goby Caspian Sea Ibragimov 1988*
Perciformes Gobiidae Ponticola bathybius (Kessler, 1877) (as Neogobius bathybius) NA Capian Sea, south-eastern part Pazooki et al. 2011
Perciformes Gobiidae Ponticola gorlap (Iljin, 1949) (as Neogobius kessleri gorlap) Caspian bighead goby Capian Sea, south-eastern part Pazooki et al. 2011
Perciformes Gobiidae Ponticola kessleri (Günther, 1861) (as Neogobius kessleri) bighead goby Caspian Sea Ibragimov 1988*
Perciformes Hexagrammidae Hexagrammos octogrammus (Pallas, 1814) masked greenling Sea of Okhotsk Skorobrechova 2009* cited in Skorobrechova et al. 2011
Perciformes Mugilidae Chelon auratus (Risso, 1810) (as Mugil auratus) golden grey mullet Caspian Sea Ibragimov 1988*
Perciformes Mugilidae Chelon auratus (Risso, 1810) (as Mugil auratus) leaping mullet Caspian Sea Ibragimov 1988*
Perciformes Percidae Gymnocephalus cernua (Linnaeus, 1758) (as Gymnocephalus cernuus) ruffe Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Baltic Sea, Finland, Tvärminne Forssell 1905
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Germany Lühe 1911
Perciformes Percidae Perca fluviatilis Linnaeus, 1758 perch Europe Van Cleave 1953
Perciformes Percidae Sander lucioperca (Linnaeus, 1758) (as Lucioperca lucioperca) zander, pike-perch Georgia, River Kura (USSR) Kurashvili et al. 1980*
Perciformes Percidae Sander lucioperca (Linnaeus, 1758) (as Lucioperca lucioperca) zander, pike-perch USSR (CIS) Izyumova 1977*
Perciformes Percidae Sander lucioperca (Linnaeus, 1758) (as Stizostedion lucioperca) zander, pike-perch Finno-Karelian ASSR Rumyantsev and Ieshko 1997*
Perciformes Sciaenidae Umbrina roncador Jordan & Gilbert, 1882 yellowfin croaker Catalina Island, California Van Cleave 1953
Perciformes Sparidae Pagrus pagrus (Linnaeus, 1758) red porgy, Couch's sea-bream, common seabream no area specified Parukhin 1966*
Perciformes Sparidae Sparus heterodus Peters, 1877 NA no area specified Parukhin 1966*
Perciformes Sphyraenidae Sphyraena barracuda (Edwards, 1771) great barracuda no area specified Parukhin 1966*
Perciformes Stichaeidae Pholidapus dybowskii (Steindachner, 1880) stichaeid fish Japan, Shikotan Island Zhukov 1960*
Perciformes Trachinidae Trachinus draco Linnaeus, 1758 weever Baltic Sea Mühling 1989
Perciformes Trachinidae Trachinus draco Linnaeus, 1758 weever Sweden Lundström 1942
Perciformes Trachinidae Trachinus draco Linnaeus, 1758 weever Germany Lühe 1911
Perciformes Trachinidae Trachinus draco Linnaeus, 1758 weever Europe Van Cleave 1953
Perciformes Trichodontidae Arctoscopus japonicus (Steindachner, 1881) Japanese sandfish Japan, Shikotan Island Zhukov 1960*
Perciformes Zoarcidae Lycodes raridens Taranetz & Andriashev, 1937 marbled eelpout Bering Sea Shults and Frost 1988
Perciformes Zoarcidae Hadropareia middendorffii Schmidt, 1904 NA Sea of Okhosk Skorobrechova 2010* cited in Skorobrechova et al. 2011
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Baltic Sea, Polen, Gdansk Bight Markowski 1938
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Sweden Lundström 1942
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Europe Van Cleave 1953
Perciformes Zoarcidae Zoarces viviparus (Linnaeus, 1758) eelpout Baltic Sea, Germany, Salzhaff Reimer and Walter 1998
Pleuronectiformes Pleuronectidae Atheresthes stomias (Jordan & Gilbert, 1880) arrow-tooth flounder British Columbia Wierzbicka and Piasecki 1998*
Pleuronectiformes Pleuronectidae Eopsetta jordani (Lockingston, 1879) petrale sole Canada Arai 1989
Pleuronectiformes Pleuronectidae Hippoglossoides platessoides (Fabricius, 1780) (as Hippoglossoides platessoides limandoides) sand-dab, long rough dab, Canadian plaice, American plaice Arctic Ocean, Greenland/Icelandic zone Olafsdottir 1999
Pleuronectiformes Pleuronectidae Hippoglossus stenolepis (Schmidt, 1904) Pacific halibut Northern Pacific Blaylock et al. 1998*
Pleuronectiformes Pleuronectidae Lepidopsetta bilineata (Ayres, 1855) rock sole Pacific coast, USA and Canada Van Cleave 1953
Pleuronectiformes Pleuronectidae Lepidopsetta bilineata (Ayres, 1855) rock sole Pacific ocean, Canada Arai 1989
Pleuronectiformes Pleuronectidae Limanda aspera (Pallas, 1814) yellowfin sole Nagaevo and Gertner Bay, Magadan, Russia, Sea of Okhotsk Skorobrechova and Nikishin 2011
Pleuronectiformes Pleuronectidae Limanda limanda (Linnaeus, 1758) (as Pleuronectes limanda) common dab Europe Van Cleave 1953
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Baltic Sea, Finland, Tvärminne Forssell 1905
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Germany Lühe 1911
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) flounder Sweden Lundström 1942
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) perch Sweden Lundström 1942
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) (as Platessa flesus) flounder Baltic Sea Mühling 1989
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) (as Pleuronectes flesus) flounder Baltic Sea, Finland, Tvärminne Forssell 1905
Pleuronectiformes Pleuronectidae Platichthys flesus (Linnaeus, 1758) (as Pleuronectes flesus) flounder Europe Van Cleave 1953
Pleuronectiformes Pleuronectidae Platichthys stellatus (Pallas, 1787) starry flounder Japan, Shikotan Island Zhukov 1960*
Pleuronectiformes Pleuronectidae Platichthys stellatus (Pallas, 1787) starry flounder Pacific coast, USA and Canada Van Cleave 1953
Pleuronectiformes Pleuronectidae Platichthys stellatus (Pallas, 1787) starry flounder Pacific ocean, Canada Arai 1989
Pleuronectiformes Pleuronectidae Pleuronectes obscurus Herzenstein, 1890 black plaice Japan, Shikotan Island Zhukov 1960*
Pleuronectiformes Pleuronectidae Reinhardtius hippoglossoides (Walbaum, 1792) turbot Atlantic, Canada Arai 1989
Pleuronectiformes Pleuronectidae Verasper moseri Jordan & Gilbert, 1898 barfin flounder Japan, Hokkaido, Erimo Cape Araki and Machida 1987*
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) trubot Baltic Sea, Finland, Tvärminne Forssell 1904
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) trubot Baltic Sea, Finland, Tvärminne Forssell 1905
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) trubot Germany Lühe 1911
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) trubot Sweden Lundström 1942
Pleuronectiformes Scophthalmidae Scophthalmus maximus (Linnaeus, 1758) (as Rhombus maximus) trubot Europe Van Cleave 1953
Salmoniformes Hemitripteridae Hemitripterus villosus (Pallas, 1814) shaggy sea raven Japan, Hokkaido, Nemuro Peninsula Nakaoka et al. 1986*
Salmoniformes Salmonidae Coregonus fera Jurine, 1825 true fera Europe Van Cleave 1953
Salmoniformes Salmonidae Coregonus lavaretus (Linnaeus, 1758) lavaret Europe Van Cleave 1953
Salmoniformes Salmonidae Oncorhynchus gorbuscha (Walbaum, 1792) pink salmon Pacific ocean, Canada Arai 1989
Salmoniformes Salmonidae Oncorhynchus gorbuscha (Walbaum, 1792) pink salmon Sakhalin Island Vyalova 2003*
Salmoniformes Salmonidae Oncorhynchus keta (Walbaum, 1792) chum salmon Sakhalin Island Vyalova 2003*
Salmoniformes Salmonidae Oncorhynchus masou (Brevoort, 1856) (as Oncorhynchus masu) masu salmon Russia Ermolenko et al. 1989*
Salmoniformes Salmonidae Oncorhynchus nerka (Walbaum, 1792) sockeye salmon Pacific ocean, Canada Arai 1989
Salmoniformes Salmonidae Salmo salar Linnaeus, 1758 salmon European USSR (CIS) Rumyantsev et al. 1998*
Salmoniformes Salmonidae Salmo trutta Linnaeus, 1758 trout European USSR (CIS) Rumyantsev et al. 1998*
Salmoniformes Salmonidae Salvelinus alpinus alpinus (Linnaeus, 1758) Arctic charr Canada, Quebec, Ungava Bay Desdevises et al. 1998*
Salmoniformes Salmonidae Salvelinus alpinus alpinus (Linnaeus, 1758) (as Salvelinus alpinus) Arctic charr River Chaun [On the helminthofauna of fish of the River Chaun.]^
Salmoniformes Salmonidae Salvelinus leucomaenis leucomaenis (Pallas, 1814) white-spotted charr Japan, Shikotan Island Zhukov 1960*
Salmoniformes Salmonidae Salvelinus leucomaenis leucomaenis (Pallas, 1814) (as Salvelinus leucomaenis) white-spotted charr Japan, Hokkaido Nagasawa et al. 1989*
Salmoniformes Salmonidae Salvelinus malma (Walbaum, 1792) dolly varden Russia Ermolenko 1994*
Salmoniformes Salmonidae Salvelinus malma (Walbaum, 1792) dolly varden Russia Ermolenko et al. 1989*
Salmoniformes Salmonidae Thymallus thymallus (Linnaeus, 1758) grayling European waters of NE Atlantic and Mediterranean Rumyantsev et al. 1999*
Scorpaeniformes Cottidae Gymnocanthus galeatus Bean, 1881 armoured sculpin Bering Sea Shults and Frost 1988
Scorpaeniformes Cottidae Gymnocanthus herzensteini Jordan & Starks, 1904 staghorn sculpin Japan, Hokkaido, Erimo Cape Araki and Machida 1987*
Scorpaeniformes Cottidae Leptocottus armatus Girard, 1854 Pacific staghorn sculpin Pacific coast, USA and Canada Van Cleave 1953
Scorpaeniformes Cottidae Myoxocephalus brandtii (Steindachner, 1867) snowy sculpin Japan, Shikotan Island Zhukov 1960*
Scorpaeniformes Cottidae Myoxocephalus polyacanthocephalus (Pallas, 1814) (as Ainocottus ensiger) great sculpin Japan, Hokkaido, Erimo Cape Araki and Machida 1987*
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) fourhorn sculpin Baltic Sea, Bothnian Bay Sinisalo and Valtonen 2003
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Sweden Lundström 1942
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Baltic Sea, Finland, Tvärminne Forssell 1904
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Baltic Sea, Finland, Tvärminne Forssell 1905
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Germany Lühe 1911
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Sweden Lundström 1942
Scorpaeniformes Cottidae Myoxocephalus quadricornis (Linnaeus, 1758) (as Cottus quadricornis) fourhorn sculpin Europe Van Cleave 1953
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) fourhorn sculpin Baltic Sea, Bothnian Bay Valtonen and Julkunen 1995
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) fourhorn sculpin Baltic Sea, North-eastern Bothnian Bay Valtonen et al. 2001
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) shorthorn sculpin Germany Lühe 1911
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) shorthorn sculpin Sweden Lundström 1942
Scorpaeniformes Cottidae Myoxocephalus scorpius (Linnaeus, 1758) (as Cottus scorpius) fourhorn sculpin Europe Van Cleave 1953
Scorpaeniformes Cottidae Myoxocephalus stelleri (Tilesius, 1811) Steller's sculpin Gertner Bay, Cape of Nyuklya near Magadan Skorobrechova and Nikishin 2014
Scorpaeniformes Cottidae Myoxocephalus stelleri (Tilesius, 1811) Steller's sculpin Sea of Okhotsk Sasaki et al. 2019
Scorpaeniformes Cottidae Taurulus bubalis (Euphrasen, 1786) sea scorpion Germany Lühe 1911
Scorpaeniformes Cyclopteridae Cyclopterus lumpus (Linnaeus, 1758) lumpfish Baltic Sea Mühling 1989
Scorpaeniformes Cyclopteridae Cyclopterus lumpus (Linnaeus, 1758) lumpfish Germany Lühe 1911
Scorpaeniformes Cyclopteridae Cyclopterus lumpus (Linnaeus, 1758) lumpfish Sweden Lundström 1942
Scorpaeniformes Cyclopteridae Cyclopterus lumpus (Linnaeus, 1758) lumpfish Europe Van Cleave 1953
Scorpaeniformes Hemitripteridae Hemitripterus villosus (Pallas, 1814) shaggy sea raven Japan, Shikotan Island Zhukov 1960*
Scorpaeniformes Hexagrammidae Hexagrammos lagocephalus (Pallas, 1810) rock greenling Japan, Shikotan Island Zhukov 1960*
Scorpaeniformes Hexagrammidae Hexagrammos lagocephalus (Pallas, 1810) rock greenling Japan, Hokkaido, Nemuro Peninsula Nakaoka et al. 1986*
Scorpaeniformes Hexagrammidae Hexagrammos octogrammus (Pallas, 1814) masked greenling Japan, Shikotan Island Zhukov 1960*
Scorpaeniformes Hexagrammidae Hexagrammos stelleri Tilesius, 1810 whitespotted greenling Gertner Bay, Cape of Nyuklya near Magadan Skorobrechova and Nikishin 2014
Scorpaeniformes Hexagrammidae Pleurogrammus azonus Jordan and Metz, 1913 Okhotsk atka mackerel Sea of Okhotsk Sasaki et al. 2019
Scorpaeniformes Sebastidae Sebastes mentella Travin, 1951 deepwater redfish, beaked redfish NW Atlantic: Norwegian Sea and Barents Sea Bakay 2001
Scorpaeniformes Sebastidae Sebastes paucispinis Ayres, 1854 bocaccio Pacific coast of USA Love et al. 2002*
Scorpaeniformes Sebastidae Sebastes trivittatus Hilgendorf, 1880 threestripe rockfish Japan, Shikotan Island Zhukov 1960*
Scorpaeniformes Sebastidae Sebastes trivittatus Hilgendorf, 1880 threestripe rockfish Pacific ocean Sasaki et al. 2019
Scorpaeniformes Triglidae Chelidonichthys capensis (Cuvier, 1829) (as Trigla capensis) Cape gurnard no area specified Parukhin 1966*
Syngnathiformes Syngnathidae Syngnathus sp. Linnaeus, 1758 seaweed pipefishes Caspian Sea Ibragimov 1988*
Pleuronectiformes Pleuronectidae Pseudopleuronectes herzensteini (Jordan and Snyder, 1901) (as Pleuronectes herzensteini) yellow striped flounder Pacific ocean Sasaki et al. 2019
Pleuronectiformes Pleuronectidae Pseudopleuronectes obscurus Herzenstein, 1890 (as Pleuronectes obscurus) darkflounder Pacific ocean Sasaki et al. 2019
Petromyzontiformes Petromyzontidae Caspiomyzon wagneri (Kessler, 1870) (as Caspiomyzon wagneri caspius) Caspian lamprey Georgia, River Kura (USSR) Kurashvili et al. 1980*
Petromyzontiformes Petromyzontidae Lampetra fluviatilis (Linnaeus, 1758) river lamprey Germany Lühe 1911
Petromyzontiformes Petromyzontidae Lampetra fluviatilis (Linnaeus, 1758) (as Petromyzon fluviatilis) river lamprey Baltic Sea Mühling 1989

Accidental hosts of Corynosoma semerme. *Source not viewed, ^Found in Host-Parasite Database NHM London without further reference details.

Host order Host family Host species Host vernacular name Geographical locality Reference
Anseriformes Anatidae Clangula hyemalis (Linnaeus, 1758) (as Nyroca hyemalis) long-tailed duck Germany Lühe 1911
Charadriiformes Laridae Larus fuscus Linnaeus, 1758 black-backed gull Baltic Sea, Finland Forssell 1905
Suliformes Phalacrocoracidae Phalacrocorax carbo (Linnaeus, 1758) great cormorant Baltic Sea, Finland Forssell 1905
Suliformes Phalacrocoracidae Phalacrocorax carbo (Linnaeus, 1758) great cormorant Germany Lühe 1911
Suliformes Phalacrocoracidae Phalacrocorax pelagicus Pallas, 1811 (as Phalacrocorax pelagicus pelagicus) pelagic cormorant North America Van Cleave 1953
Carnivora Canidae Canis lupus familiaris Linnaeus, 1758 (as Canis familiaris) Husky dog North America Van Cleave 1953
Carnivora Canidae Vulpes lagopus Linnaeus, 1758 (as Alopex lagopus) Arctic fox, polar fox European USSR (CIS) Yushkov 1995*
Carnivora Canidae Vulpes lagopus Linnaeus, 1758 (as Alopex lagopus) Arctic fox, polar fox St. Lawrence Island, Bering Sea, Alaska Rausch et al. 1990
Carnivora Mustelidae Mustela erminea Linnaeus, 1758 stoat Sweden Lundström 1942
Carnivora Mustelidae Mustela putorius Linnaeus, 1758 (as Putorius foetorius) European polecat Germany Lühe 1911
Carnivora Mustelidae Neovison vison (Schreber, 1777) (as Mustela vison) mink Finland Nuorteva 1966
Carnivora Mustelidae Neovison vison (Schreber, 1777) (as Mustela vison) American Mink Iceland Skirnisson 1995
Cetartiodactyla Eschrichtiidae Eschrichtius robustus (Lilljeborg, 1861) (as Eschrichtius gibbosus) gray/grey whale Arctic Ocean, Pacific Ocean [Whales and dolphins. Monographic outline.]^
Cetartiodactyla Phocoenidae Phocoena phocoena (Linnaeus, 1758) harbour porpoise Germany Lühe 1911
Cetartiodactyla Phocoenidae Phocoena phocoena (Linnaeus, 1758) harbour porpoise Northern Atlantic [Whales and dolphins. Monographic outline.]^
Cetartiodactyla Phocoenidae Phocoena phocoena (Linnaeus, 1758) harbour porpoise Arctic Ocean, Northern Pacific Ocean [Whales and dolphins. Monographic outline.]^
Cetartiodactyla Phocoenidae Phocoena phocoena (Linnaeus, 1758) (as Phocoena communis) harbour porpoise Finland, Tvärminne Forssell 1904
Cetartiodactyla Phocoenidae Phocoena phocoena (Linnaeus, 1758) (as Phocoena communis) harbour porpoise Baltic Sea, Finland Forssell 1905

Accidental hosts of Corynosoma strumosum. * Source not viewed.

Host order Host family Host species Host vernacular name Graphical locality Reference
Accipitriformes Accipitridae Haliaeetus leucocephalus (Linnaeus, 1766) Bald eagle North America, Alaska Van Cleave 1953
Anseriformes Anatidae Clangula hyemalis (Linnaeus, 1758) oldsquaw Europe Mühling 1989
Anseriformes Anatidae Mergus merganser Linnaeus, 1758 common merganser Germany Lühe 1911
Anseriformes Anatidae Mergus serrator Linnaeus, 1758 red-breasted merganser Germany Lühe 1911
Anseriformes Anatidae

Somateria mollissima (Linnaeus, 1758)

eider duck Iceland Skirnisson and Jonsson 1996
Charadriiformes Alcidae

Uria lomvia

(Linnaeus, 1758)

thick-billed murre Point Barrow, Alaska Rausch et al. 1990
Charadriiformes Laridae Larus argentatus Pontoppidan, 1763 herring gull Finland Forssell 1905
Charadriiformes Laridae

Larus glaucescens

Naumann, 1840

glaucoused-winged gull Napaskiak, Alaska Rausch et al. 1990
Charadriiformes Laridae

Larus hyperboreus Gunnerus, 1767

glaucous gull Bear Island, Barents Sea Sagerup et al. 2000
Charadriiformes Laridae Sterna hirundo Linnaeus, 1758 common tern Sweden Lundström 1942
Podicipediformes Podicipedidae Podiceps grisegena (Boddaert, 1783) red-necked grebe Germany Lühe 1911
Suliformes Phalacrocoracidae

Phalacrocorax auritus

(Lesson, 1831)

double-crested cormorant Germany Lühe 1911
Suliformes Phalacrocoracidae

Phalacrocorax carbo

(Linnaeus, 1758)

great cormorant

France: Bretagne,

Baltic Sea: Finland and Germany

Forssell 1905,

Lühe 1911, Reimer 2002*

Suliformes Phalacrocoracidae Phalacrocorax pelagicus Pallas, 1811 pelagic cormorant Barents Sea, Alaska Rausch et al. 1990
Carnivora Canidae

Canis familiaris

Linnaeus, 1758

domestic dog Alaska Van Cleave 1953
Carnivora Canidae

Canis familiaris

Linnaeus, 1758

domestic dog

(as sledge dog)

Tununak, Alaska Rausch et al. 1990
Carnivora Canidae Vulpes lagopus (Linnaeus, 1758) (as Alopex lagopus) Arctic fox, polar fox St. Lawrence Island, Bering Sea, Alaska Rausch et al. 1990
Carnivora Canidae

Vulpes vulpes

(Llinnaeus, 1758)

red fox

Hopper Bay, Cold Bay,

Alaska

Rausch et al. 1990
Carnivora Felidae

Felis catus

Linnaeus, 1758

domestic cat Germany Lühe 1911
Carnivora Mustelidae

Enhydra lutris

(Linnaeus, 1758)

sea otter Alaska Van Cleave 1953
Carnivora Mustelidae Lutra lutra (Linnaeus, 1758) European otter Eire, Northern Ireland, England, Wales, Isle of Man, Orkneys, Shetlands, Scotland

McCarthy and Hassett 1993*,

Jefferies et al. 1990, Weber 1991

Carnivora Mustelidae

Mustela putorius

Linnaeus, 1758

European polecat Germany Lühe 1911
Carnivora Mustelidae

Neovison vison

(Schreber, 1777)

mink Oregon, North America Van Cleave 1953
Carnivora Mustelidae

Neovison vison

(Schreber, 1777)

mink Finland Nuorteva 1966
Cetacea Phocoenidae

Phocoena phocoena

(Linnaeus, 1758)

harbour porpoise Tvärminne, Finland Forssell 1904, Forssell 1905, Lühe 1911
Primates Hominidae

Homo sapiens

Linnaeus, 1758

human Chevak, Alaska Rausch et al. 1990

While for C. magdaleni, all definitive host records belong to the family Phocidae (order Carnivora), the definitive hosts for C. semerme include, besides numerous Phocidae, also Otariidae and Odobenidae from the same order and Monodontidae (belonging to the order Artiodactyla) (Table 3). For this reason, more paratenic hosts of Corynosoma semerme in Europe and North America are reported (Table 4), but which all are also Actinopterygii. Monoporeia affinis (Amphipoda) is the only known intermediate host of Corynosoma semerme (Nybelin 1924). Some further intermediate hosts are suggested for the Baltic Sea area, mainly isopods (Saduria entomon, Asellus aquaticus), amphipods (Gammarus spp.) ostracods and Mysidae, because such invertebrate species were found in the intestines of infected paratenic fish (e.g. Valtonen and Julkunen 1995). From North America, the intermediate host is still unknown.

For C. strumosum, an arthropod (probably an amphipod) is suggested as an intermediate host in North America (Van Cleave 1953), which is similar to the suggested intermediate hosts in Europe. Recently, Skorobrechova and Nikishin (2019) found corynosome cystacanths in Spinulogammarus ochotensis (Brandt, 1851), which further confirmed amphipods as potential intermediate hosts. Corynosoma strumosum seems to have fewer definitive hosts than C. semerme (Table 5), but the species shows also numerous reported paratenic hosts in Europe, North America, the Caspian Sea, Sea of Okhotsk and Northwest Pacific (Table 6), belonging to the classes Actinoptergyii and Petromyzonti. Even if the Corynosoma spp. are observed in many fish species, they are not able to become sexually mature in fish (Forssell 1905, Lundström 1942). This is the reason why fish may only play an important role as paratenic host.

The definitive host of Corynosoma has fish as prey, but numerous fish-eating species become accidentally infected and become dead-end hosts (see Tables 7, 8 C. semerme and C. strumosum, respectively). While it is not known how long a life cycle of Corynosoma spp. takes, the development of the cystacanths to become mature helminths in seals is suggested to take 2-3 weeks (Helle and Valtonen 1981) and the season and/or temperature might have a strong effect on the sex-age structure of Corynosoma spp. (Helle and Valtonen 1981, Popov and Fortunato 1987).

Aznar et al. (2006) characterised the marine Corynosoma clade as cosmopolitan and, in the past, the marine genus was able to adapt their complex life cycle to extreme environments like the brackish Baltic Sea, Lake Saimaa and the Caspian Sea. It is also postulated that the right intermediate and paratenic host is available and serves as a reservoir for the cystacanth. Marine glacial relict species serve or are supposed to serve as intermediate hosts for Corynosoma species in the Baltic Sea (e.g. the amphipod Monoporeia affinis (Lindström, 1855) and the isopod Saduria entomon (Linnaeus, 1758)). Lundström (1942) discussed the idea that the Corynosoma spp., like Echinorhynchus salmonis Müller, 1784, may be a marine glacial relict species, because these species are also found in the Arctic Sea, White Sea and numerous freshwater and relict lakes (e.g. Lake Saimaa, Lake Ladoga, Lake Onega).

Sinisalo and Valtonen (2003) mentioned, that the C. semerme cystacanths, observed in Baltic fish, differed clearly in the morphological characters (trunk length), while C. magdaleni and C. strumosum cystacanths were hard to separate (C. strumosum only slightly larger than C. magdaleni). This is interesting, especially since also Waindok et al. (2018) mentioned some difficulties with the identification of C. strumosum. Acanthocephalans from harbour seals of the North Sea were initially diagnosed as C. strumosum, based on morphological characters; however, molecular markers (COI and ITS) indicated that they should have been assigned to C. magdaleni.

Another study, Hernández-Orts et al. (2017), based on partial sequences of the mitochondrial cytochrome c oxidase 1 gene (cox1), clearly segregated the Northern Hemisphere species (C. magdaleni and C. strumosum) and Southern Hemisphere species (C. hannae and C. australe Johnston, 1937). Corynosoma hannae from the Southern Hemisphere is most similar to C. semerme from the Northern Hemisphere, having no genital spines in females. It could be possible that parallel evolution may have evolved two similar complex parasitic Corynosoma systems in pinnipeds. It is still unresolved, whether the only report of C. semerme from the Southern Hemisphere by Johnston and Edmonds (1953) is C. hannae or not (discussed by Hernández-Orts et al. 2017).

Another possible assumption could be that the marine genus, Corynosoma, entered the Baltic Sea at the same time as their definitive hosts and this reflects their population history. The Baltic grey seal population is suggested to have diverged from the Eastern Atlantic/North Sea ones between 4,200 and 10,000 years ago (Fietz et al. 2016, Klimova et al. 2014), when the breeding habitats were shifted more easterly during the Baltic Sea formation. For the ringed seal, the allele frequency differentiation between the Baltic and Arctic populations were weak (Palo et al. 2001), while a northern invasion from continental seals during the Plio-Pleistocene to the basins was suggested to be most likely (Palo and Väinölä 2006). The ringed seal is the exclusive seal species in the land-locked Lake Saimaa, Finland. It also formed isolated populations in the Arctic and North-western Pacific (Popov and Fortunato 1987). The Caspian seal is another very isolated population and is supposed to be a relict species as well. Today, the ringed seal is very isolated in the Baltic Sea, as well as a small population of harbour seals (Härkönen et al. 2005).

Conclusion

Obviously, with the geographical isolation, Corynosoma species show plastic morphological characters and possible morphotypes (e.g. Popov and Fortunato 1987, Amin et al. 2011). Which role the intermediate and paratenic host play in the isolation is not known today. Sinisalo and Valtonen (1998) found an indication of segregation of C. magdaleni and C. strumosum in their paratenic hosts in the Gulf of Bothnia, Baltic Sea, Finland. In general, there is too little information available on the ecology and distribution of each of the Corynosoma spp. Future studies should try to combine genetic and new morphological tools (like SEM and the proboscis profiler) to throw more light on the on-going species and morphotype discussion for Corynosoma spp. We see the greatest challenge is the access to good and sufficient material for further analyses. Our reported geographical distribution patterns (Suppl. material 1) and summary of definitive and paratenic hosts may contribute to and motivate further investigations on this interesting parasite group.

Corynosoma semerme and C. strumosum have extensive host and geographical ranges, providing opportunities for reproductive isolation of lineages. Speciation in acanthocephalans is often cryptic and Waindok et al. (2018) have already demonstrated the presence of a cryptic species, "Candidatus Corynosoma nortmeri," in the North Sea. Further work to investigate the species diversity in Corynosoma will require a tandem morphological and molecular study of acanthocephalans collected from all known hosts, throughout their geographical ranges. The present study should prove to be a useful guide for future sampling efforts.

Acknowledgements

The Swedish Taxonomy Initiative (grant # dha 2017.4.3-16) and Riksmusei Vänner foundation funded this project.

Grant title

Swedish thorny-headed worms (Acanthocephala: Corynosoma spp.) in grey (Halichoerus grypus) and ringed seals (Pusa hispida).

References

Supplementary material

Suppl. material 1: R script for generating geographical distribution maps. 
Authors:  Leidenberger S., Boström S. & Wayland M.
Data type:  R script