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In total, 11 digenean species, Macvicaria georgiana, M. microtestis, Helicometra rakusai, Lepidapedon balgueriasi, L. garrardi, Neolepidapedon trematomi, Derogenes johnstoni, Gonocerca phycidis, Genolinea bowersi, Elytrophalloides oatesi and Glomericirrus macrouri, were found in the alimentary tract of fishes of the family Nototheniidae in the Weddell Sea. The pelagic fish, Aethotaxis mitopteryx, was free of Digenea; eight benthic and bentho-pelagic species of the genus Trematomus were infected. The highest level of the infection was found for T. loennbergi (diversity of parasites - 10 species, prevalence 76%, intensity up to 23 specimens, mean abundance 5.00). The total number of digenean species occurring in Nototheniidae in subcontinental waters and off the South Shetland Islands was found to be 21. The diversity of parasites in the Weddell Sea (11) was similar to those in three other areas, off the South Shetland Islands (12), off Adelie Land (11) and in the Ross Sea (12), but the level of infection in the Weddell Sea was much lower, especially much lower than in the South Shetland Islands area. It is probably related to the lack of shallow sub-coastal waters in the Weddell Sea (presence of shelf glaciers). Four digenean species are probably endemic for the entire Eastern Antarctica, whereas one endemic Antarctic species, M. georgiana, absent in other areas of the Eastern Antarctica, is the dominant species in both the Weddell Sea and the South Shetland Islands areas.
Infection levels of six fish species-representing the family Nothoteniidae-with external parasite Eubrachiella antarctica (Quidor, 1906) (Copepoda) were studied in the season of 1978/79. The prevalence and the intensity of infection of individual fish species on different fishing grounds of the Atlantic sector of Antarctic were determined. In addition the density analysis of the parasite occurrence on different parts of fish body was carried out as well as the relationship between the infection parameters and the body length of the studied fish species.
Neolepidapedoides subantarcticus sp. nov. (Digenea, Lepocreadiidae) is reported from the intestine, mainly the jejunum, of fishes in the eastern mouth of the Beagle Channel and in the harbour of Ushuaia in the Beagle Channel (Tierra del Fuego, Argentina) at a depth 7–30 m. The typical host is Patagonotothen longipes, other hosts are P. tessellata, P. brevicauda and Champsocephalus esox. The male terminal genitalia indicates that the new species belongs to the genus Neolepidapedoides (Lepocreadiidae, Lepocreadiinae). The most important taxonomic features are the presence of eye-spots, the spined tegument, the “Opechona-type” cirrus-sac, the external seminal vesicle free in the parenchyma, the gonads arranged in tandem, the vitelline follicles extending from the level of the oesophagus in the forebody to the posterior end of the body and an I-shaped excretory vesicle reaching to the intestinal bifurcation and the absence of a pseudoesophagus. Ten previously described species differ from the N. subantarcticus sp. nov. mainly in the extent of the vitelline fields and length of the excretory vesicle which reaches into forebody.
Six of seven fish species of Artedidraconidae caught in the Weddell Sea were infected with Digenea. Prevalence of infection was relatively high, 18-71%, but intensities were very low, never exceeding four digeneans. In all, 10 digenean species were found: Macvicaria microtestis, Stenakron glacialis, Lepidapedon garrardi, Neolepidapedon trematomi, Steringophorus arntzi, Genolinea bowersi, Derogenes johnstoni, Elytrophalloides oatesi, Glomericirrus macrouri, and Otodistomum cestoides (metacercaria). None of these species was specific for Artedidraconidae. According to literature data, the total number of digeneans of Artedidraconidae is 14 species, of which 12 have been identified, including the 10 listed above, Neolebouria terranovaensis and Lecithaster macrocotyle; two (possibly specific for Artedidraconidae) are undetermined yet. The low diversity of digenean species in areas other than the Weddell Sea (three species in each of three areas) is probably the result of limited data available so far. Knowledge of the digenean fauna of Artedidraconidae is much less complete than that of three other notothenioid families, Nototheniidae, Channichthyidae and Bathydraconidae.
Trematomus newnesi (Nototheniidae), a bentho-pelagic fish, caught off Adelie Land (eastern Antarctic) was examined for the presence of internal parasitic worms. These fishes were infected with 11 species and larval forms of parasites: Digenea (Macvicaria pennelli, Neolebouria terranovaensis, Genolinea bowersi, and Elytrophalloides oatesi), larval Cestoda (two forms of tetraphyllidean metacestodes, bilocular form and trilocular form, and diphyllobothriid plerocercoids), Acanthocephala (Metacanthocephalus camp- belli, M. johnstoni) and larval Nematoda (Contracaecum osculatum, C. radiatum). Larval cestodes were the dominant parasites, whereas acanthocephalans were relatively rare. Five species and larval forms were recorded also in fish caught in the Davis Sea. A check list of parasites of T. newnesi recorded in the eastern- and western Antarctic comprises 21 species and larval forms. Probably, T. newnesi plays an important role in life cycles of parasitic worms in the Antarctic.
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