Phylogenetic relationship between Contracaecum spp. (Nematoda, Anisakidae) parasitizing cormorants (Aves, Phalacrocoracidae) from Argentina

Abstract Anisakidae nematodes have a wide host and geographic distribution. Species of the genus Contracaecum parasitize aquatic organisms such as piscivorous birds and mammals as their definitive hosts. Several Contracaecum species have been reported parasitizing Phalacrocoracidae in South America. The aim of this work is to highlight phylogenetic relationships between Contracaecum species parasitizing shags based on both molecular markers and the papillae pattern arrangement on the male tail. Some Contracaecum specimens parasitizing Red-legged cormorants from the Ría Deseado (RD), and other nematodes parasitizing eight dead Neotropic cormorants from San Miguel del Monte lagoon (SMML), Argentina, were collected and analyzed. An integrative analysis allowed us to recognize Contracaecum chubutensis parasitizing Phalacrocorax gaimardi , and Contracaecum australe parasitic in Phalacrocorax brasilianus . According to obtained mtDNAcox2, ITS1, ITS2, and SSrRNA isolates, Contracaecum sp. parasitizing P. gaimardi matched with the previously reported C. chubutensis parasitizing P. atriceps from Bahía Bustamante, Chubut province. Likewise, Contracaecum sp. isolates parasitizing P. brasilianus clustered with C. australe from Chile. Besides, the papillae pattern arrangement of the male tail allowed us to understand the interspecific and genetic relationships between the Contracaecum species. The analysis confirm that C. chubutensis specimens parasitizing P. gaimardi from RD represent a new host and the southernmost record for the species. Whereas, those C. australe specimens parasitizing P. brasilianus from SMML provide a new geographical record for the species and the extension of its distribution range. Present results also confirm the inland and marine distribution of C. australe and C. chubutensis , respectively.