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

Abstract

The genus Pseudoterranova includes parasite species of cetaceans and pinnipeds. The third stage larva (L3) of seal-infecting species occur in second intermediate or paratenic fish hosts mainly in neritic waters. This study firstly describes a Pseudoterranova L3 from meso/bathypelagic fishes off Macaronesia. L3s were morphologically and genetically studied by light microscopy and sequencing of the mtDNA cox2 and entire ITS rDNA genes. Bayesian inferences were performed with sequences from the larvae and selected sequences from GenBank. The nematode L3s were molecularly identified as Pseudoterranova ceticola, a parasite of kogiid whales. Such larvae were collected from Bolinichthys indicus, Chauliodus danae, Eupharynx pelecanoides, Diaphus rafinesquii, D. mollis, Diretmus argenteus and Maulisia argipalla. They mainly occurred in the viscera of these fishes. Pseudoterranova ceticola L3 were small (< 12 mm) and whitish, and a prominent characteristic is a circumoral ridge extending from the ventral boring tooth which differentiate them from Pseudoterranova spp. L3 maturing in pinnipeds and Terranova sensu lato larvae that mature in poikilotherms. The shape of the tail: conical, long, pointed, ventrally curved and lacking mucron also distinguish these larvae from those of the pinniped-infecting Pseudoterranova spp. Phylogenetic analyses based on mtDNA cox2 and ITS rDNA sequences suggest that P. ceticola is closely related to Skrjabinisakis spp., and not with Pseudoterranova spp. parasitizing pinnipeds. The related species Skrjabinisakis paggiae, S. brevispiculata and S. physeteris (until recently belonging to genus Anisakis), are as P. ceticola also parasites of physeteroid cetaceans. The morphology and morphological variation of the larvae of the cetacean parasite P. ceticola is thoroughly described for the first time. These L3 can readily be morphologically distinguished from those of the pinniped-infecting Pseudoterranova spp. The parasite likely completes its life cycle in the mesopelagic and bathypelagic realm, with meso/bathypelagic fish as 2nd intermediate or paratenic hosts and kogiids as final host. Thus, Pseudoterranova from cetaceans appear to be morphologically, genetically, and ecologically differentiated to those from pinnipeds, suggesting that they are not congeneric.

Morphological and Molecular Characterization of Anisakid Nematode Larvae (Nematoda: Anisakidae) in the Black Cusk eel Genypterus maculatus from the Southeastern Pacific Ocean off Peru

“…Safonova et al [44] proposed the resurrected generic status of Peritrachelius for A. typica, and the use of Skrjabinisakis as a genus name rather than a subgenus for A. brevispiculata, A. paggiae, and A. physeteris based on the intraspecific genetic distances of ITS sequences. These observations were also indicated by Takano and Sata [45] and Bao et al [46], who use multiple genetic markers and indicate the validity of the genus Skrjabinisakis. Our results also provide conclusive proof of the validity of the genus Skrjabinisakis.…”

Anisakid parasite diversity in a pygmy sperm whale, Kogia breviceps (Cetacea: Kogiidae) stranded at the edge of its distribution range in the Northeast Atlantic Ocean

“…Adult specimens of this species have been reported in a pygmy sperm whale stranded on the Iberian coast of the Northeast Atlantic [ 1 , 2 ], in tropical waters of the Central Eastern Atlantic Ocean (Caribbean Sea and Florida coast) [ 7 , 53 ], and in warm Australian waters [ 49 ]. At larval stages, this species has been identified only in mesopelagic and bathypelagic fish species from tropical warm/temperate waters (revised in Bao et al, 2022 [ 4 ]).…”

“…The occurrence of larval stages of S. paggiae in mesopelagic fish [ 23 ], S. brevispiculata in myctophids [ 6 ], and P. ceticola in mesopelagic and bathypelagic fish species [ 4 ] suggests that these species interact with hosts that develop in the deep-water or meso-/bathypelagic realms of marine ecosystems. Further studies on mesopelagic and bathypelagic fauna in the Northeast Atlantic could shed light on the intermediate/transport hosts for these species, thus elucidating the life cycles of these parasites in these northern waters.…”