WoRMS taxon details
Hydrichthys Fewkes, 1887
117123 (urn:lsid:marinespecies.org:taxname:117123)
accepted
Genus
Hydrichthys mirus Fewkes, 1887 (type by monotypy)
Ichthyocodium Jungersen, 1913 · unaccepted (synonym)
- Species Hydrichthys boycei Warren, 1916
- Species Hydrichthys cyclothonis Damas, 1934
- Species Hydrichthys mirus Fewkes, 1887
- Species Hydrichthys pacificus Miyashita, 1941
- Species Hydrichthys pietschi Martin, 1975
- Species Hydrichthys sarcotretis (Jungersen, 1913)
marine, brackish, fresh, terrestrial
recent only
Fewkes, J.W., 1887. A hydroid parasitic on a fish. Nature, Lond. 36 : 604-605., available online at https://www.biodiversitylibrary.org/page/18672095
page(s): 604 [details]
page(s): 604 [details]
Taxonomic remark The first complete life cycle of a Hydrichthys hydroid was revealed by Larson (1982). He could identify the resulting...
Taxonomic remark The first complete life cycle of a Hydrichthys hydroid was revealed by Larson (1982). He could identify the resulting medusa as Stomotoca pterophylla Haeckel, 1879. Because his hydroid showed little host specificity and many other Hydrichthys polyps are rather similar, Larson concluded that they will also produce medusae referable to the genus Stomotoca L. Agassiz, 1862. Therefore, he suggested to synonymize Hydrichthys and Stomotoca. This was contested by Arai (1989) and Boero & Bouillon (1989). The latter authors could show that the type species of Stomotoca – S. atra L. Agassiz, 1862 – had a polyp stage that was completely different from Hydrichthys (free living, with scattered tentacles). Moreover, the polyp of a tentatively identified Hydrichthys mirus Fewkes, 1887 – type species of the genus Hydrichthys – produced a Leuckartiara-like medusa (Boero et al., 1991). Because Stomotoca pterophylla and Stomotoca atra have different polyps, Boero et al. (1991) proposed the new genus Larsonia for S. pterophylla.
More life-cycle information on various other Hydrichthys hydroids could show an even larger array of medusa morphologies and some might be referred to known medusa based genera.
Because the Hydrichthys polyps produce medusae belonging to different genera, it must be assumed that the Hydrichthys-like polyp evolved several times convergently through a simplification and adaptation to the parasitic mode of life. Just like for many Bougainvillia hydroids, the Hydrichthys hydroids offer few morphological traits to distinguish reliably separate species. The host specificity seems not to be very strict neither (Millard, 1975; Larson, 1982). Hydrichthys species identification is therefore difficult and assignments to nominal species should generally only be made when the material comes from approximately the same geographic region as the type specimen. It remains thus not beyond any doubt that the medusa of Hydrichthys mirus Fewkes, 1887 corresponds to the medusa described by Boero et al. (1991) based on a colony from Papua New Guinea, whereas H. mirus was originally described from New England. Further clarification of the genus depends on the rearing and identification of mature medusae of each nominal Hydrichthys species based on material from the original biogeographic region. [details]
More life-cycle information on various other Hydrichthys hydroids could show an even larger array of medusa morphologies and some might be referred to known medusa based genera.
Because the Hydrichthys polyps produce medusae belonging to different genera, it must be assumed that the Hydrichthys-like polyp evolved several times convergently through a simplification and adaptation to the parasitic mode of life. Just like for many Bougainvillia hydroids, the Hydrichthys hydroids offer few morphological traits to distinguish reliably separate species. The host specificity seems not to be very strict neither (Millard, 1975; Larson, 1982). Hydrichthys species identification is therefore difficult and assignments to nominal species should generally only be made when the material comes from approximately the same geographic region as the type specimen. It remains thus not beyond any doubt that the medusa of Hydrichthys mirus Fewkes, 1887 corresponds to the medusa described by Boero et al. (1991) based on a colony from Papua New Guinea, whereas H. mirus was originally described from New England. Further clarification of the genus depends on the rearing and identification of mature medusae of each nominal Hydrichthys species based on material from the original biogeographic region. [details]
Schuchert, P.; Choong, H.; Galea, H.; Hoeksema, B.; Lindsay, D.; Manko, M.; Pica, D. (2025). World Hydrozoa Database. Hydrichthys Fewkes, 1887. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=117123 on 2025-04-16
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Nomenclature
original description
Fewkes, J.W., 1887. A hydroid parasitic on a fish. Nature, Lond. 36 : 604-605., available online at https://www.biodiversitylibrary.org/page/18672095
page(s): 604 [details]
original description (of Ichthyocodium Jungersen, 1913) Jungersen, H.F.E., 1913. On a new gymnoblastic hydroid (Ichthyocodium sarcotretes ) epizoic on a new parasitic copepod (Sarcotretes scopeli) infesting Scopelus glacialis Rhdt. Vidensk. Meddr dansk naturh. Foren. 64 : 1-38, pls. 1-2.
page(s): 24 [details]
basis of record van der Land, J.; Vervoort, W.; Cairns, S.D.; Schuchert, P. (2001). Hydrozoa, <B><I>in</I></B>: Costello, M.J. <i>et al.</i> (Ed.) (2001). <i>European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels,</i> 50: pp. 112-120 (look up in IMIS) [details]
page(s): 604 [details]
original description (of Ichthyocodium Jungersen, 1913) Jungersen, H.F.E., 1913. On a new gymnoblastic hydroid (Ichthyocodium sarcotretes ) epizoic on a new parasitic copepod (Sarcotretes scopeli) infesting Scopelus glacialis Rhdt. Vidensk. Meddr dansk naturh. Foren. 64 : 1-38, pls. 1-2.
page(s): 24 [details]
basis of record van der Land, J.; Vervoort, W.; Cairns, S.D.; Schuchert, P. (2001). Hydrozoa, <B><I>in</I></B>: Costello, M.J. <i>et al.</i> (Ed.) (2001). <i>European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels,</i> 50: pp. 112-120 (look up in IMIS) [details]
Taxonomy
status source
Schuchert, P. (2007). The European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Filifera part 2. <em>Revue suisse de Zoologie.</em> 114: 195-396.
page(s): 359 [details]
page(s): 359 [details]
Other
From editor or global species database
Taxonomic remark The first complete life cycle of a Hydrichthys hydroid was revealed by Larson (1982). He could identify the resulting medusa as Stomotoca pterophylla Haeckel, 1879. Because his hydroid showed little host specificity and many other Hydrichthys polyps are rather similar, Larson concluded that they will also produce medusae referable to the genus Stomotoca L. Agassiz, 1862. Therefore, he suggested to synonymize Hydrichthys and Stomotoca. This was contested by Arai (1989) and Boero & Bouillon (1989). The latter authors could show that the type species of Stomotoca – S. atra L. Agassiz, 1862 – had a polyp stage that was completely different from Hydrichthys (free living, with scattered tentacles). Moreover, the polyp of a tentatively identified Hydrichthys mirus Fewkes, 1887 – type species of the genus Hydrichthys – produced a Leuckartiara-like medusa (Boero et al., 1991). Because Stomotoca pterophylla and Stomotoca atra have different polyps, Boero et al. (1991) proposed the new genus Larsonia for S. pterophylla.More life-cycle information on various other Hydrichthys hydroids could show an even larger array of medusa morphologies and some might be referred to known medusa based genera.
Because the Hydrichthys polyps produce medusae belonging to different genera, it must be assumed that the Hydrichthys-like polyp evolved several times convergently through a simplification and adaptation to the parasitic mode of life. Just like for many Bougainvillia hydroids, the Hydrichthys hydroids offer few morphological traits to distinguish reliably separate species. The host specificity seems not to be very strict neither (Millard, 1975; Larson, 1982). Hydrichthys species identification is therefore difficult and assignments to nominal species should generally only be made when the material comes from approximately the same geographic region as the type specimen. It remains thus not beyond any doubt that the medusa of Hydrichthys mirus Fewkes, 1887 corresponds to the medusa described by Boero et al. (1991) based on a colony from Papua New Guinea, whereas H. mirus was originally described from New England. Further clarification of the genus depends on the rearing and identification of mature medusae of each nominal Hydrichthys species based on material from the original biogeographic region. [details]
| Language | Name | |
|---|---|---|
| Japanese | サカナヤドリヒドラ属 | [details] |
