Asaccotrema vietnamiense n. gen.; n. sp. (Trematoda: Monorchioidea), a new aberrant representative of lissorchiid trematodes from the sidestripe rasbora, Rasbora paviana Tirant (Actinopterygii: Cyprinidae), Vietnam

Sokolov, Sergey G., Gordeev, Ilya I. (2019): Asaccotrema vietnamiense n. gen.; n. sp. (Trematoda: Monorchioidea), a new aberrant representative of lissorchiid trematodes from the sidestripe rasbora, Rasbora paviana Tirant (Actinopterygii: Cyprinidae), Vietnam. Zootaxa 4674 (4): 451-462, DOI: 10.11646/zootaxa.4674.4.

Parasites of the Antarctic toothfish (Dissostichus mawsoni Norman, 1937) (Perciformes, Nototheniidae) in the Pacific sector of the Antarctic

The Antarctic toothfish (Dissostichus mawsoni Norman, 1937) is one of the main target species of commercial fisheries in the Antarctic. It is an endemic and is found along the shelf of Antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-Antarctic. It feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. This article presents new data on toothfish infection in the Pacific sector of the Antarctic. Specimens were examined during commercial longline fishing in the Ross Sea and the Amundsen Sea in January–February 2013. Fourteen species of parasites were found using standard parasitological methods and genetic analysis.Keywords:  Toothfish; parasites; Antarctic fisheries; CCAMLR; infection; Southern Ocean.(Published: 24 June 2016)Citation: Polar Research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.2936

Phylogenetic Evidence for the Lissorchiid Concept of the Genus Anarhichotrema Shimazu, 1973 (Trematoda, Digenea)

Anarhichotrema Shimazu, 1973 is a monotypic digenean genus, with the type- and only species, Anarhichotrema ochotense Shimazu, 1973, known to infect North Pacific fishes. This genus was originally described as a member of the Lissorchiidae (Monorchioidea) and later moved to the Zoogonidae (Microphalloidea). Its exact phylogenetic position has remained unresolved due to the lack of molecular data. In this study, we isolated specimens of A. ochotense from the Bering wolffish, Anarhichas orientalis Pallas, 1814 caught in the Sea of Okhotsk, described them morphologically and performed a molecular phylogenetic analysis of their nuclear 18S and 28S rDNA regions. The specimens examined in our study generally corresponded to previous morphological descriptions of A. ochotense but were noticeably smaller, possibly due to the crowding effect. The phylogenetic analysis placed Anarhichotrema within the Lissorchiidae as a sister taxon to the group comprising freshwater lissorchiids. Thus, we restore Anarhichotrema to the Lissorchiidae, as originally assigned

Abnormal gonads in the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 [Perciformes: Nototheniidae]): the first record and histological description

This paper describes the morphology and histology of abnormal gonads in Antarctic toothfish (Dissostichus mawsoni) and the possibility of intersexuality and senescence of some individuals. Two old (approximately 25 years) and large (184–185 cm) specimens with abnormal gonads were caught in the Antarctic during commercial fishing for toothfish and studied using histological methods. Although D. mawsoni is well-known and extensively studied, this is the first study dealing with abnormal gonads in the species. The histological analysis revealed that the gonads of the first specimen contained both male and female germ cells (ovotestis), the testicular and ovarian tissues being separated by a thick layer of connective tissue. The female portion was composed of secondary vitellogenic oocytes, primary vitellogenic, cortical alveolar and primary growth oocytes, while the testes contained cysts of spermatogonia and primary spermatocyte. The gonads of the second specimen were small, filiform and showed massive growth of the connective tissue, which occupied almost the entire gonad; a few spermatogonia without visible cysts were found. This study extends our understanding of sexual development in Antarctic toothfish, documenting the possibility of long-term interruptions in the reproductive cycle of this species

Phylogenetic Evidence for the Lissorchiid Concept of the Genus <i>Anarhichotrema</i> Shimazu, 1973 (Trematoda, Digenea)

Anarhichotrema Shimazu, 1973 is a monotypic digenean genus, with the type- and only species, Anarhichotrema ochotense Shimazu, 1973, known to infect North Pacific fishes. This genus was originally described as a member of the Lissorchiidae (Monorchioidea) and later moved to the Zoogonidae (Microphalloidea). Its exact phylogenetic position has remained unresolved due to the lack of molecular data. In this study, we isolated specimens of A. ochotense from the Bering wolffish, Anarhichas orientalis Pallas, 1814 caught in the Sea of Okhotsk, described them morphologically and performed a molecular phylogenetic analysis of their nuclear 18S and 28S rDNA regions. The specimens examined in our study generally corresponded to previous morphological descriptions of A. ochotense but were noticeably smaller, possibly due to the crowding effect. The phylogenetic analysis placed Anarhichotrema within the Lissorchiidae as a sister taxon to the group comprising freshwater lissorchiids. Thus, we restore Anarhichotrema to the Lissorchiidae, as originally assigned

Abnormal gonads in the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 [Perciformes: Nototheniidae]): the first record and histological description

This paper describes the morphology and histology of abnormal gonads in Antarctic toothfish (Dissostichus mawsoni) and the possibility of intersexuality and senescence of some individuals. Two old (approximately 25 years) and large (184–185 cm) specimenswith abnormal gonadswere caught in the Antarctic during commercial fishing for toothfish and studied using histological methods. Although D. mawsoni is well-known and extensively studied, this is the first study dealing with abnormal gonads in the species. The histological analysis revealed that the gonads of the first specimen contained both male and female germ cells (ovotestis), the testicular and ovarian tissues being separated by a thick layer of connective tissue. The female portion was composed of secondary vitellogenic oocytes, primary vitellogenic, cortical alveolar and primary growth oocytes, while the testes contained cysts of spermatogonia and primary spermatocyte. The gonads of the second specimen were small, filiform and showed massive growth of the connective tissue, which occupied almost the entire gonad; a few spermatogonia without visible cystswere found. This study extends our understanding of sexual development in Antarctic toothfish, documenting the possibility of long-term interruptions in the reproductive cycle of this species

Parasites of the Blue Antimora, Antimora rostrata and Slender Codling, Halargyreus johnsonii (Gadiformes: Moridae), in the Northwestern Atlantic

12 pages, 3 figures, 3 tablesPurpose The blue antimora, Antimora rostrata and slender codling, Halargyreus johnsonii (Gadoformes: Moridae) are common representatives of deep-water marine demersal fish fauna. This paper focuses on infections in blue antimora caught in the northwestern Atlantic region, but also reports observations on the parasites of slender codling obtained from a limited number of specimens from the same location. Methods Standard methods of parasitological examination, fixation and staining were used. In addition, a genetic analysis of the found acanthocephalans was performed to clarify their taxonomic affiliation. Results Blue antimora is mostly infected by juveniles of Anisakis sp. and trematodes Lepidapedon sp. sensu Campbell & Bray, 1993. The trematode Lepidapedon cf. mariannae and nematodes Spinitectus oviflagellis, Fellicola sp., Hysterothylacium gadi gadi, and Capillaria cf. gracilis have been recorded from blue antimora for the first time. The slender codling has been newly recorded as a host of five parasite species: Steringophorus pritchardae; Plerurinae gen. sp.; Lepidapedon cf. mariannae; Ascarophis sp.; Anisakis sp., and Sphyrion lumpi. Conclusions Blue antimora and slender codling are recorded as hosts of 14 and 5 parasite taxa, respectively. The parasite fauna of these two species have similar patterns of infection to other bony fish that exist at a similar depth (800–2000) within the studied regionThe research was supported by the Russian Science Foundation (Grant no. 17-74-10203). Specimens collection and transportation were supported by the Russian Foundation for Basic Research (Grant no. 16–04–00516)Peer reviewe

Morphological study of otoliths of Antimora microlepis and Antimora rostrata (Actinopterygii: Gadiformes: Moridae)

16 pages, 3 tables, 7 figuresA comparative morphological investigation of otoliths from two species of Antimora, A. microlepis and A. rostrata was conducted to identify distinguishing species-specific characteristics. Some of the identified characters were shared between the two species studied. Ontogenetic changes in otolith morphology of the two morids studied were evident between small and larger specimens. Otoliths of small-sized individuals have shown the same degree of similarity with the large-sized individualsPeer reviewe

Composition of leucocytes in peripheral blood of Patagonian toothfish (Dissostichus eleginoides, Smitt, 1898) (Nototheniidae)

The composition of leukocytes in the Patagonian toothfish (Dissostichus eleginoides Smitt, 1898), caught in the Scotia Sea at a depth of more than 1000 m, was studied. Cells with various morphofunctional characteristics and cell structure were found. Lymphocytes were predominant, followed by, in decreasing order, eosinophils, monocytes, blast forms and neutrophils. The composition of leukocytes in the Patagonian toothfish consists of the same types of leukocytes as the earlier studied Antarctic toothfish (Dissostichus mawsoni Norman, 1937), but the percentage of white blood cells in the leukocyte formula differs between the two species