Occurrence of Anisakis physeteris Baylis, 1923 and Pseudoterranova sp. (Nematoda) in pygmy sperm whale Kogia breviceps (De Blainvillei, 1838) (Physeteridae) in northeastern coast of Brazil

A first record of digenean parasites of the dwarf sperm whale Kogia sima with morphological and molecular information

Two species of digenean trematodes of the family Brachycladiidae were obtained from two male dwarf sperm whales Kogia sima that stranded along the island of Kyushu, southern Japan in 2017. From the liver of the first animal, a single, large gravid specimen of a digenean species was collected. The morphological features were consistent with those of the genus Brachycladium. The worm had a large body and was characterized by anterior caeca without lateral diverticula, the shape of testes, ovary, and eggs. Molecular analyses using gene sequences of the 28S rRNA and the mitochondrial NADH dehydrogenase subunit 3 also supported the inclusion of this specimen into the genus Brachycladium. The identity of this worm is undetermined due to the lack of information on the genus and is reported as Brachycladium sp. From the cranial sinuses of the second animal, 33 specimens of digeneans were collected that were morphologically identified as Nasitrema gondo. This report documents a new host record for N. gondo, and the sequence information is provided for this digenean for the first time. This is the second record of digenean parasites for the family Kogiidae, and the first record with morphological and molecular information. The possibility of digenean infection in the liver and cranial sinus should be kept in mind during the necropsy of stranded kogiids.

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

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.

First Report of the Parasitic Nematode Pseudoterranova spp. Found in Mediterranean Monk Seal (Monachus monachus) in Greece: Conservation Implications

The Mediterranean monk seal (Monachus monachus) is classified as an endangered species by the IUCN, with a global population that does not exceed 800 individuals. There is limited understanding around the biology and health status of the species, rendering possible parasitic infections grave for its conservation efforts. The aim of the current study was the molecular identification of a parasitic nematode found in the digestive system of a sub-adult Mediterranean monk seal individual, that was found stranded in the area of Pagasitikos Gulf, Greece in 2019. Analysis of the stomach contents revealed the presence of two intact female nematode individuals. Standard protocols were followed as DNA extraction of the parasites was conducted and PCR amplification of the cytochrome oxidase subunit I (COI) mitochondrial gene was implemented. Sequencing analysis of a 585 bp-amplified product displayed a 96% similarity of the screened nematodes to the Pseudoterranova bulbosa species. Bayesian inference was implemented for the subsequent tree reconstruction. The phylogenetic tree revealed a clear genetic similarity between our parasitic nematode individuals named as Pseudoterranova spp. and Pseudoterranova bulbosa (bootstrap value: 82%), which is indicated for the first and only time as such, to be found in the waters of the Mediterranean Sea and also in the stomach of a Mediterranean monk seal.

Anisakid larva parasitizing Plagioscion squamosissimus in Marajó Bay and Tapajós River, state of Pará, Brazil

In November 2014 and May 2015, a total of 44 specimens of the South American silver croaker Plagioscion squamosissimus were collected: 30 in Marajó Bay and 14 in the Tapajós River, state of Pará, Brazil. The aim was to investigate the presence of anisakid nematodes and determine their parasitism indices and sites of infection, because of their importance regarding health inspection. Sixty-nine Anisakis sp. larvae were found; among them, 16 larvae in seven fish collected in Marajó Bay and 53 larvae in four fish in the Tapajós River. The parasitism indices of the nematodes collected from the fish in Marajó Bay comprised prevalence (P) of 23%, mean infection intensity (MI) of 2.28, mean abundance (MA) of 0.53, range of infection (RI) of 1-4, and infection site (IS) in the mesentery. The fish from the Tapajós River showed P = 28%, MI = 13.2, MA = 3.8, RI = 1-22, and IS = mesentery and intestine. To assist in taxonomic identification, images of the specimens obtained through optical microscopy with Nomarski's interferential contrast system and scanning electron microscopy were used. This is the first record of Anisakis sp. parasitizing P. squamosissimus.

Anisakis Dujardin, 1845 infection (Nematoda: Anisakidae) in Pygmy Sperm Whale Kogia breviceps Blainville, 1838 from west Pacific region off the coast of Philippine archipelago

Cetaceans are definitive hosts of anisakid nematodes known to cause human anisakidosis. Despite the reported strandings of different cetaceans in the Philippines, studies on anisakids from these definitive hosts are limited. Here, the morphologically and molecularly identified anisakid species, specifically those of the genus Anisakis Dujardin, 1845 in stranded Pygmy Sperm Whale Kogia breviceps Blainville, 1838 in the west Pacific region off Philippine waters are presented. Morphological data using SEM and LM revealed multi-infections with different Anisakis species belonging to Anisakis type I and type II groups. Molecularly, PCR-RFLP on the ITS rDNA and sequence data analyses of both ITS rDNA and mtDNA cox2 regions identified those from Anisakis type I group as A. typica (Diesing, 1860), whereas those from type II group as A. brevispiculata Dollfus, 1968, and A. paggiae Mattiucci et al. (Syst Parasitol 61:157-171, 2005). This is the first record of Anisakis infection from this host stranded in the west Pacific region off the coast of Philippine waters and new geographical record for A. paggiae.

Stranding Events of Kogia Whales along the Brazilian Coast

The genus Kogia, which comprises only two extant species, Kogia sima and Kogia breviceps, represents one of the least known groups of cetaceans in the global ocean. In some coastal regions, however, stranding events of these species have been relatively common over the last decades. Stranding provides the opportunity to investigate the biology of these cetaceans and to explore the epidemiological aspects associated with the mortality of the organisms found on the beach. A number of disturbances (including pelagic fisheries, chemical pollution, boat strikes, and noise pollution) have been confirmed to pose a particular threat to the Kogia species. However, no study has yet investigated potential relationships between environmental conditions and stranding events. Here we analyse how a collection of environmental, physical, and biological variables, such as wind, sea surface temperature (SST), water depth, and chlorophyll-a, correlate to Kogia stranding events along the Brazilian coast. The results of our statistical analyses suggest that K. sima is more likely found in warm tropical waters, which provide an explanation for the high frequency of stranding in northeastern Brazilian coast. In contrast, K. breviceps appears to have a preference for temperate and productive waters. Wind speed results to be also an important factor for predicting Kogia strandings in Brazilian coast. Additionally, literature information in combination with our own data and analyses of stomach contents confirms that oceanic cephalopods constitute the primary nutritional source of both Kogia species. By using the available information as a qualitative proxy for habitat preference and feeding ecology, our study provides a novel and comprehensive assessment of Kogia stranding data in relation to environmental conditions along the Brazilian coast.

Anisakid nematodes from stranded pygmy sperm whales, Kogia breviceps (Kogiidae), in three localities of the Yucatan Peninsula, Mexico

The present paper reports the presence of 3 adult and juvenile anisakid nematode species: Anisakis simplex, A. brevispiculata, and Pseudoterranova ceticola, which were recovered from the digestive tract of stranded pygmy sperm whales (Kogia breviceps) from 3 localities along the coast of the Yucatan Peninsula. The presence of these anisakid adult nematodes suggests that larval stages may occur in cephalopods or fishes used for human consumption, which represents a potential danger to public health. The occurrence of the 3 anisakid species in coastal waters of the Yucatan Peninsula represents new geographical records for Mexico.

Relato de nematóides da família Anisakidae em bacalhau comercializado em Ribeirão Preto, SP

A anisaquíase é uma parasitose gastrointestinal dos seres humanos, resultante da ingestão acidental de larvas infectantes de nematóides da família Anisakidae. Foram analisadas 11 amostras de bacalhau sendo que 64% estavam em desacordo com a legislação em vigor por conter nematóides da família Anisakidae e, portanto, impróprias para o consumo.

Evidence for a new species of Anisakis Dujardin, 1845: morphological description and genetic relationships between congeners (Nematoda: Anisakidae)

In the present study, a new biological species of Anisakis Dujardin, 1845, was detected in Kogia breviceps and K. sima from West Atlantic waters (coast of Florida) on the basis of 19 (nuclear) structural genes studied by multilocus allozyme electrophoresis. Fixed allele differences at 11 enzyme loci were found between specimens of both adults and larvae of the new species and the other Anisakis spp. tested. Reproductive isolation from A. brevispiculata Dollfus, 1968 was demonstrated by the lack of hybrid or recombinant genotypes in mixed infections in K. breviceps. Genetic distance of the new species from its closest relative, A. brevispiculata, was D(Nei)=0.79. The new species is morphologically different from the other species which have been genetically characterised and from the other Anisakis retained by Davey (1971) as valid or as species inquirendae: the name of Anisakis paggiae n. sp. is proposed for the new taxon. Anisakis Type II larvae (sensu Berland, 1961) from the European hake Merluccius merluccius in the northeastern Atlantic Ocean (Galician coast) and from the scabbard fish Aphanopus carbo in Central Atlantic waters (off Madeira), were identified as A. paggiae n. sp. Its genetic relationships with respect to the seven species previously characterised (A. simplex (Rudolphi, 1809) sensu stricto), A. pegreffii Campana-Rouget & Biocca, 1955, A. simplex, (A. typica (Diesing, 1860), A. ziphidarum Paggi et al., 1998, A. physeteris Baylis, 1923 and A. brevispiculata) were also inferred. Overall, a low genetic identity was detected at allozyme level between the eight Anisakis species. Interspecific genetic identity ranged from I(Nei)=0.68, between the sibling species of the A. simplex complex, to I(Nei)=0.00 (no alleles shared at the considered loci) when A. physeteris, A. brevispiculata and the new species were compared with the other species of the genus. Concordant topologies were obtained using both UPGMA and NJ tree analyses for the considered species. In both analyses, A. paggiae n. sp. clustered with A. brevispiculata. They also indicated two main clades, the first including A. physeteris, A. brevispiculata and A. paggiae n. sp., the second containing all of the remaining species (i.e. A. simplex (s.s.), A. pegreffii, A. simplex, A. typica and A. ziphidarum). A deep separation between these two main Anisakis clades, also supported by high bootstrap values at the major nodes, was apparent. This is also supported by differences in adult and larval morphology, as well as with respect to their main definitive hosts. A morphological key for distinguishing adult A. paggiae n. sp., A. physeteris and A. brevispiculata is presented. Allozyme markers for the identification of any life-history stage of the Anisakis spp. so far studied, as well as ecological data on their definitive host preferences and geographical distribution, are updated.