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In total, 400 bony fishes of 32 species (7 families) were examined. Acanthocephalans occurred in 55 host specimens of 15 species. Five species were recognised, including 3 echinorhynchid species maturing in fish, Metacanthocephalus campbelli (Leiper et Atkinson, 1914), M. dalmori Zdzitowiecki, 1983 and Echinorhynchuspetrotschenkoi (Rodjuk, 1984), as well as cystacanths of 2 polymorphid species maturing in seals, Corynosoma bullosum (Linstow, 1892) and C. pseudohamanni Zdzitowiecki, 1984. All species were found in fish in the Weddell Sea for the first time. M. dalmori, E. petrotschenkoi and C. bullosum were not previously recorded in the high Antarctic. Out of 26 host/parasite relationships, 24 are new. The level of infection was very low. Only 114 acanthocephalan specimens were found, with the maximum intensity of 12 cystacanths in one Trematomus pennelli. C. bullosum was the most abundant species (53% of all specimens). Out of 11 fish species examined in numbers of 18-46 specimens, only 6 were infected. Trematomus scotti was the most strongly infected - prevalence 54%, relative density 1.04.
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.
Four nematode species are reported from bony fishes caught in the Weddell Sea. Two species of cystidicolids, Cystidicola beatriceinsleyae (Holloway et Kiewer, 1969) and Ascarophis nototheniae Johnston et Mawson, 1945, were found in Lycodichthys antarcticus Pappenheim, 1911, whereas one capillariid, Capillaria (Procapillaria) sp., and one anisakid, Paranisakiopsis weddelliensis sp. nov., in Macrourus whitsoni Regan, 1913. Capillaria (Procapillaria) sp. (only females were found) is characterised by: body 17.6-26.0 mm long; stichosome composed of 46-49 stichocytes; presence of a vulvar appendage, and eggs 77-82 × 37-42 µm. This is the first Capillaria species reported from fishes in the Antarctic. Paranisakiopsis weddelliensis sp. nov. is characterised by: body length of male and female 40-48 and 55-62 mm, respectively; lips up to 200 µm and interlabia up to 140 µm long; inconspicuous dentigerous ridge on each lip; 8-10 pairs of preanal and 4 pairs of postanal papillae; spicules equal or subequal, 420-620 µm; eggs 83-85 × 63-65 µm. P. weddelliensis is the first representative of this genus reported from the Antarctic.
In total, 60 fish specimens belonging to four families, Zoarcidae (19 specimens of three species), Liparididae (14 specimens of two species), Macrouridae (23 specimens of one species) and Rajidae (four specimens of two species), caught in the Weddell Sea were examined. A zoarcid, Lycodichthys dearborni, and both Rajidae, Bathyraja maccaini and Bathyraja sp., were not infected. Macrourus whitsoni was the most strongly infected (six digenean species found, prevalence 91.3%, mean abundance 10.13). Two zoarcids, Ophthalmolycus amberensis and O. bothriocephalus, were infected with Macvicaria longibursata; the former also with Aphanurus sp., Paraliparis antarcticus and P. trilobodon were infected with Steringophorus liparidis and Neolebouria terranovaensis, and Derogenes johnstoni, respectively. The check list of Digenea recorded in Antarctica in non- notothenioid fishes is given. Infected fishes belong to six families, Zoarcidae (7 digenean species found), Macrouridae (8), Muraenolepididae (9), Liparididae (5), Bathylagidae (one) and Rajidae (one). In total, 29 digenean species were found, of which 12 are common for Notothenioidei and other fishes, whereas 17 species are specific for non-notothenioid definitive hosts. Digenea belong to four higher taxa, Opecoelidae (10 species), Lepocreadiidae (10), Fellodistomidae (one) and Hemiuroidea (8).
Helicometra pisanoae sp. n. (Digenea, Opecoelidae) is described based on adult specimens from a fish, Trematomus hansoni (Nototheniidae) caught at the Adelie Land (Eastern Antarctic). The newly described species belongs to the group of species with the terminal, infundibuliform oral sucker. The other diagnostic features are: the sucker ratio based on mean diameter 1:0.84-1.02, blind intestinal caeca, the genital pore closely anterior to the intestinal bifurcation, the cirrus sac reaching posteriorly to the level of posterior half of the ventral sucker and the vitelline follicles reaching to the level of the ventral sucker.
In total, 1446 Antarctic and subantarctic teleosts were examined for nematodes. One species, Ascarophis nototheniae Johnston et Mawson, 1945, is reported. New data on the biometrical variability and the occurrence or absence of this species are given. Three areas of the West Antarctic (the South Shetland Islands, South Georgia and South Orkneys) as well as three areas of the East Antarctic (Davis Sea, Weddell Sea and off Adelie Land) are new geographical localities for this nematode species. Also, 21 fish species represent new host records for A. nototheniae. Two predatory channichthyid species, Chaenocephalus aceratas and Cryodraco antarcticus are the most strongly infected fishes in all examined areas, except the Weddell Sea.
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.
Steringophorus arntzi sp. n. is described from notothenioid fishes, Bathydraco marri (type-host, Bathydraconidae) and Dolloidraco longedorsalis (Artedidraconidae). This species resembles S. furciger (Olsson, 1868), but it is distinguished from that by eggs with a short filament, entire ovary (only with irregular margins), less elongate body and a post-bifurcal genital pore. Its area of distribution, the Antarctic, is distant from that of S. furciger (in the north hemisphere). Steringophorus liparidis sp. n. is described from Paraliparis antarcticus (Liparididae). This species resembles S. thulini Bray et Gibson, 1980, but it is distinguished by eggs with a spine on the anopercular pole, longer intestinal caeca, vitelline fields situated more anteriorly in relation to the ventral sucker, different hosts (liparidids contrary to gadiforms) and area of distribution (the Antarctic contrary to the north Atlantic). Occurrence of fellodistomid digeneans in the Antarctic subcontinental waters is recorded for the first time.
The following opecoelid digeneans are described from bony fishes of the Weddell Sea: Neolebouria terranovaensis Zdzitowiecki, Pisano et Vacchi, 1993 from Paraliparis antarcticus (Liparididae, new host family); Helicometra rakusai sp. n. from Trematomus loennbergi (Nototheniidae); Stenakron glacialis Zdzitowiecki, 1989 from Racovitzia glacialis (Bathydraconidae) and Pogonophryne marmorata (Artedidraconidae, new host family). H. rakusai sp. n. has terminal oral sucker (similarly to the second Antarctic species, H. antarcticae Holloway et Bier, 1968), but its ventral sucker is considerably smaller than the oral sucker - sucker ratio based on mean diameter 1:0.71-0.87 (mean 1:0.81), that based on width 1:0.65-0.99 (mean 1:0.83). Both other species are recorded in the Weddell Sea for the first time.
In total, 404 fishes of 34 species were examined and 678 digenean specimens found. Apart from data on Macrourus whitsoni previously published, 40 specimens of teleost fishes belonging to 14 species and six families were infected with Hemiuroidea; 91 specimens belonging to seven species and four families were collected. Metacercariae of Otodistomum cestoides (Beneden, 1871) (family Azygiidae) occurred in cysts on the mesentery. The remaining species, Genolinea bowersi (Leiper et Atkinson, 1914) and Aphanurus sp. (Bunocotylidae); Derogenes johnstoni Prudhoe et Bray, 1973 and Gonocerca phycidis Manter, 1925 (Derogenidae); Elytrophalloides oatesi (Leiper et Atkinson, 1914) and Glomericirrus macrouri (Gaevskaya, 1975) (Hemiuridae), occurred as adults in the alimentary tract. A single specimen of Aphanurus sp. probably belongs to a new species, but is a little distorted and lacks eggs. The other species were found in 17 new hosts. O. cestoides, G. bowersi and D. johnstoni were found in the Weddell Sea for the first time. G. macrouri occurred mainly in fishes living in deep waters (below 300 m), whereas E. oatesi (rare in the investigated area) mainly in shallower waters.
Three lepocreadiid digenean species of two genera, Neolepidapedon Manter, 1954 and Lepidapedon Stafford, 1904, occur in notothenioid fishes of the genera Trematomus (Nototheniidae), Artedidraco and Pogonophryne (both Artedidraconidae), Bathydraco and Prionodraco (both Bathydraconidae) in the Weddell Sea. Descriptions of all species, including a new one and two previously recorded in the high Antarctic, are given. Neolepidapedon trematomi Prudhoe et Bray, 1973 is recorded in 4 host species, three of the genus Trematomus (2 new host species) and Pogonophryne permitini (new host species and family), for the first time in the Weddell Sea and south to 70°S. Lepidapedon garrardi (Leiper et Atkinson, 1914) and L. balgueriasi sp. n. belong to the “Beveridgei subgroup” of Bray and Gibson (1995). L. garrardi has the excretory vesicle reaching to the level of the border between the testes and it is transferred to this subgroup from the “Garrardi subgroup”, which is renamed to the “Zubchenkoi subgroup”. This species is recorded in 9 host species (7 new hosts), for the first time in the Weddell Sea. L. balgueriasi sp. n. is recorded in 4 species of the genus Trematomus, including T. loennbergi (type-host). This species has eggs similar in number and size to L. garrardi (egg length exceeding 0.1 mm), but it has relatively smaller suckers and pharynx, and vitelline follicles confluent in the forebody and dorsally to the testes; its site is in the pyloric caeca and anterior part of the small intestine. A key to species of the “Beveridgei subgroup” of the genus Lepidapedon is given.
Four digenean species, Stenakron glacialis, Lepidapedon garrardi, Steringophorus arntzi and Otodistomum cestoides (metacercariae) were recorded in three of four bathydraconid species (59 specimens) examined in the Weddell Sea. The only previously reported species, Elytroplicilloides oatesi, was found there only in other hosts. The total number of digenean species known as occurring in Bathydraconidae in Antarctica increased to 13. They were recorded in eight of ten host species examined. However, only a few specimens of most of bathydraconid species were investigated. Most of digenean species are more abundant in other fishes, especially in Nototheniidae and Channichthyidae. S. arntzi and S. glacialis normally occur in Bathydraco marri and Racovitzia glacialis respectively, but they were occasionally found also in Artedidraconidae; the latter was reported also from a liparidid. Intensities of infections are usually low, except in three large predatory species, Parachaenichthys charcoti, P. georgianus and Cygnodraco mawsoni, which can be parasitized by about 100 or more digeneans in some single hosts.
As a result of the examination in the Weddell Sea of 59 channichthyid fishes belonging to six species, only three fish specimens of two species, Chionodraco hamatus (one of 20) and Cryodraco antarcticus (two of seven), were found to be infected with Digenea. Three digenean species, Macvicaria georgiana, Derogenes johnstoni and Glomericirrus macrouri, were recognized. The infection was extremely low - one or two parasites in each infected fish. All these digenean species are more abundant in the Weddell Sea in other fishes. Results were compared with literature data for three other Antarctic areas, the environs of Adelie Land, the South Shetland Islands and the Ross Sea (off Terra Nova Bay). Channichthyidae are much more highly infected in these areas and with higher diversity of parasites - in total 12 species. The low infection of channichthyids in the Weddell Sea is probably associated with the presence of shelf glaciers (instead of a sub-coastal environment) and the feeding of these fishes mainly on pelagic organisms. No one digenean species is specific for Channichthyidae, but in areas others than the Weddell Sea Channichthyidae are important hosts of eight digenean species.
In total, 400 bony fishes caught at a depth 120-1540 m in the east part of the Weddell Sea were examined and 63 fishes of 4 families occurring at depths of 120-590 m were infected with Macvicaria spp. Three species (185 specimens) were recognised, including two new species, M. microtestis sp. n. and M. longibursata sp. n., and one species, M. georgiana (Kovalyova et Gaevskaya, 1974), previously recorded only in the Western Antarctic. M. microtestis sp. n. occurs in nototheniids (Trematomus spp.) and artedidraconids. It has testes smaller than the ovary and which are entirely obscured by vitelline follicles dorsally. M. longibursata sp. n. occurs in two zoarcid species. It has the cirrus sac extending far posterior to the ventral sucker. M. georgiana occurs in eight species of the genus Trematomus (Nototheniidae) and in Cryodraco antarcticus (Channichthyidae); six host species are new. A key to seven species of the genus Macvicaria occurring in the Antarctic is presented.
In total, 23 fishes caught at depth 625-1540 m were examined and 21 found to be infected with digeneans belonging to 6 species, 4 lepocreadiids in the intestine and 2 hemiuroids in the stomach. Three lepocreadiid species are described as new: Lepidapedon brayi sp. n., L. ninae sp. n. and Paralepidapedon awii sp. n. Some morphological data for other species are given. Postlepidapedon opisthobifurcatus (Zdzitowiecki, 1990) and Glomericirrus macrouri (Gaevskaya, 1975) are reported from the high Antarctic for the first time and in new hosts. Gonocerca phycidis Manter, 1925 is found in a new host. The total number of digenean species recorded in M. whitsoni increased from 2 to 8.
In total, 404 fishes of 34 species caught in the Weddell Sea were examined, including four specimens of skates, Bathyraja maccaini and Bathyraja sp., and 23 specimens of the gadiform fish, Macrounis whitsoni (the only three species infected with adult Cestoda). Skates were infected with four representatives of the order Tetraphyllidea, Marsupiobothrium awii sp. n., Anthocephalum siedlecka (syn. Phyllobothrium siedleckii), Anthocephalum arctowskii (syn. Phyllobothrium arctowskii), Oncobothrium antarcticum. The three last species were first described in the South Shetland Islands area. Phyllobothrium siedleckii from B. maccaini (new host) and P. arctowskii from Bathyraja sp. are transferred to the genus Anthocephalum and their descriptions are emended. Marsupiobothrium awii sp. n. from B. maccaini is characterised by: apolytic strobila; scolex with four sessile, jar-like bothridia, each with opening provided with a ring of muscles and submarginal sucker; 120-150 testes; vagina with dilatation in proximal part and sphincter present distally; eggs 0.016 x 0.017 mm. Differential diagnosis with remaining species of the Marsupiobothrium is given. Oncobothrium antarcticum was found in B. maccaini (new host). M. whitsoni was infected with one pseudophyllidean species, Parabothriocephalus johnstoni, previously known as only from the same host in the Indian sector of the Antarctic Ocean.
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