First record of Contracaecum australe (Nematoda: Anisakidae) infecting Neotropic cormorant (Phalacrocorax brasilianus) (Aves: Phalacrocoracidae) in southern Brazil with a phylogenetic analysis.

Phalacrocorax brasilianus (Gmelin, 1789) (Aves: Phalacrocoracidae) is one of the few piscivorous birds inhabiting freshwater and saline environments, being considered one of the most abundant aquatic species in Rio Grande do Sul, Brazil, especially along the state's coastline. It is known that birds are hosts to a wide variety of disease-causing agents, among them, nematodes of the Contracaecum (Anisakidae) have a large number of recognized species. However, little is still known about the occurrence of these parasites in the Southern region of Brazil. Herein we identified for the first time Contracaecum australe Garbin, Mattiucci, Paoletti, González-Acuña, and Nascetti, 2011 (Nematoda: Anisakidae) parasitizing P. brasilianus in Southern Brazil. Nematodes found in the bird's proventriculus were subjected to morphometric analyses, by optical microscopy and scanning electron microscopy, and molecular analyses. Molecular phylogeny based on the analysis of the 18S, ITS-1, 5.8S and ITS-2 genes showed our sequences identical to those of C. australe. Therefore, this is the first record of C. australe in southern Brazil, expanding the geographical distribution of the parasite species in the country. Additionally, new molecular sequences are being provided, contributing to the knowledge of Contracaecum species parasitizing cormorants.