Integrative taxonomy of anisakid nematodes in stranded cetaceans from Brazilian waters: an update on parasite's hosts and geographical records.

Anisakidae are represented mainly by species of Anisakis Dujardin, 1845, Pseudoterranova Krabbe, 1878, and Contracaecum Railliet and Henry, 1913. Integrative taxonomy, based on morphological and genetic approaches, can provide a precise identification of species, increasing the knowledge of their systematics, biology, and evolution. In this study, integrative taxonomy was applied in order to identify, at generic and/or specific taxonomic level, 245 anisakids from 63 cetaceans of 12 different species, which stranded in the Brazilian coast. Parasites from nine hosts were preserved by freezing and, from 54 hosts, were fixed in 70% ethanol (n = 43) or alcohol-formalin-acetic (n = 11) for a period varying from 6 to 19 years. The morphological analysis allowed the identification of 171 specimens at genus level: 120 as Anisakis sp. clade I, 47 as Anisakis sp. clade II, and four as Pseudoterranova sp. From those 15, specimens were identified at species level, seven as Anisakis typica, seven as Anisakis paggiae and one as Anisakis brevispiculata. Moreover, 74 specimens were identified as belonging to Anisakidae family. The genetic analysis based on cox2 gene allowed the identification/confirmation of Anisakis typica (n = 33), Anisakis paggiae (n = 1), and for the first time in the Brazilian coast, Anisakis brevispiculata (n = 4) and Anisakis ziphidarum (n = 1). Additionally, a probably new Anisakis species, genetically close to A. paggiae, is reported infecting a dwarf sperm whale. The results clearly indicated that the preservation of nematodes influenced significantly on the level of taxonomic definition, in both morphological and, mainly, genetic analyses. Pseudoterranova sp. was identified for the first time in the spinner dolphin, Stenella longirostris. The detection of nine A. paggiae specimens, in three Kogia breviceps animals, substantiates the austral occurrence of this species. The identification of A. brevispiculata in Kogia sima and K. breviceps confirms Kogiidae whales as their most common hosts. Anisakis typica was corroborated as a generalist species, the most widely distributed in the Brazilian coast, infecting a broad variety of Delphinidae and Kogiidae, with two new geographical records in Stenella frontalis and Lagenodelphis hosei. The study showed a new scenery of parasite diversity of marine anisakids, updating the Anisakis species distribution.