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.
Two species of Lernanthropus de Blainville, 1822 parasitic on the sparid fish Pagrus pagrus L., 1758 and the sciaenid fish Umbrina canosai Berg, 1895, respectively, from the coastal zone of the State of Rio de Janeiro, Brazil, are redescribed and illustrated: L. caudatus Wilson, 1922, and L. leidyi Wilson, 1922. The male specimens of L. caudatus are described for the first time. There are new geographical and host records for these Lernanthropus species.
In total, 400 teleosts of 32 species (7 families) were examined. Cercoids of Tetraphyllidea (about 41 thousands) occurred in 204 host specimens of 26 species. Three morphological forms of cercoids were recognized. They were cercoids with bothridia divided into two and three loculi, and cercoids with subcylindrical bothridia. All forms were found in fishes from the Weddell Sea for the first time. Cercoids with bilocular bothridia were the most abundant form (90.7% of all specimens); cercoids with trilocular bothridia and cercoids with subcylindrical bothridia were less numerous (6.6 and 2.7% of all specimens, respectively). Cercoids concentrated in obligatory or facultative predators, whereas pelagic and bentho-pelagic fishes feeding on crill, were rarely infected. Chionodraco hamatus was the most heavily infected - prevalence 100%, relative density 903.
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