First report on molecular identification of Anisakis simplex in Oncorhynchus nerka from the fish market, with taxonomical issues within Anisakidae

Abstract

Alive anisakids cause acute gastrointestinal diseases, and dead worms contained in food can provoke sensibilization and allergic reactions in humans. Detected in the purchased minced salmon Oncorhynchus nerka nematodes were identified as Anisakis simplex sensu stricto (Anisakidae). We found that recently published phylogenetic trees (reconstructed using different ribosomal and mitochondrial genetic markers) showed independent clusterization of species recognized in the A. simplex sensu lato species complex. This prompted us to undertake this full-fledged molecular genetics study of anisakids from Kamchatka with phylogenetic reconstructions (NJ/ML) and calculated ranges of interspecific and intergeneric p-distances using ITS1-5.8S-ITS2 sequences. We confirmed that molecular markers based on the ITS region of rDNA were able to recognize 'pure' specimens belonging to the cryptic species. We offer new insights into the systematics of anisakids. The genus Anisakis sensu stricto should include Anisakis simplex sensu stricto, Anisakis pegreffii, Anisakis berlandi, Anisakis ziphidarum, and Anisakis nascettii. Presumably, two genera should be restored in the structure of the subfamily Anisakinae: Skrjabinisakis for the species Anisakis paggiae, Anisakis brevispiculata, and Anisakis physeteris; and Peritrachelius for the species Anisakis typica. In addition, we provide the short annotated list of some genera of the family Anisakidae, including their diagnoses.

Characterization of Pseudoterranova ceticola (Nematoda: Anisakidae) larvae from meso/bathypelagic fishes off Macaronesia (NW Africa waters)

“…In the cox 2 BI tree, adult P. ceticola from K. breviceps (DQ116435), larva from the fish S. undosquamis (ON155434), larva from the fish Katsuwonus pelamis (LC712860) and the sequences of the present Terranova -like larvae group together in a well-supported clade, representing a sister group to a clade with Skrjabinisakis physeteris , S. brevispiculata and S. paggiae (until recently belonging to the genus Anisakis (see 20 , 21 ) and related sequences (Fig. 4 and see also Figure S1 at Supplementary files which details the intraspecific variations and relationships of P. ceticola ).…”

“…paggiae , S. brevispiculata , S. physeteris and Skrjabinisakis sp. 2 (species which until most recently belonged to the genus Anisakis 20 , 21 ). The BI analysis of the ITS region also supports that P. ceticola is closely related to the former S. physeteris complex clade.…”

Zoonotic diseases of fish and their prevention and control

“…These nematodes are all globally or regionally considered as highly significant. The most common fish nematodes of the Anisakidae family include genera Anisakis , Pseudoterranova , and Contracaecum with worldwide distribution and are amongst the most reported larvae in marine parasites and are of considerable zoonotic importance (Borges et al 2012 ; Shamsi and Suthar 2016 ; Bao et al 2019 ; Safonova et al 2021 ). Since their discovery in 1960, there has been an increased interest in the family Anisakidae .…”

Morphological identification of Skrjabinisakis Mozgovoi, 1951 (Nematoda: Anisakidae) in Kogia sima (Cetacea: Kogiidae) from Brazilian waters

“…Few authors have used these subgeneric names (Takano & Sata, 2022). Safonova et al (2021) proposed the use of Skrjabinisakis as a genus name rather than a subgenus for Anisakis physeteris (Baylis, 1923), A. brevispiculata (Dollfus, 1966 and A. paggiae Mattiucci, Nascetti, Dailey, Webb, Barros, Cianchi & Bullini, 2005, and the resurrected generic status of Peritrachelius for A. typica. Takano & Sata (2022), in their studies based on molecular data, do not assign A. typica to Peritrachelius, since the species was nested in Anisakis s.s., with similar phylogenetic relationship for A. simplex s.s. and A. typica observed by cox1 sequences.…”