Redescription of Cercopithifilaria bainae Almeida & Vicente, 1984 (Spirurida, Onchocercidae) from a dog in Sardinia, Italy

Background: Three species of the genus Cercopithifilaria have been morphologically and molecularly characterized in dog populations in southern Europe: Cercopithifilaria grassii (Noe, 1907), Cercopithifilaria sp. sensu Otranto et al., 2011 (reported as Cercopithifilaria sp. I), and Cercopithifilaria sp. II sensu Otranto et al., 2012. The adults of Cercopithifilaria sp. I have remained unknown until the present study. Methods: The material originated from a dog from Sardinia (Italy) diagnosed with dermal microfilariae of Cercopithifilaria sp. I. The holotype and three paratypes of Cercopithifilaria bainae Almeida & Vicente, 1984, described from dogs in Brazil, were studied as comparative material. A cox1 (similar to 689 bp) and 12S (similar to 330 bp) gene fragments were amplified and phylogenetic analysis carried out. Results: The highest numbers of adult nematodes (82%) were collected in the sediment of the subcutaneous tissues of the trunk (n = 37) and forelimbs (n = 36). The morphology of the adult nematodes and microfilariae collected from the dog in Sardinia corresponded to those of C. bainae. All cox1 and 12S gene sequences showed a high homology (99-100%) with sequences from microfilariae of Cercopithifilaria sp. I. Conclusions: The morphological and molecular identity of the microfilariae of C. bainae overlap those described previously as Cercopithifilaria sp. sensu Otranto et al., 2011 (=Cercopithifilaria sp. I). Therefore, the present study reports the occurrence of C. bainae in Europe, for the first time after its description and the single record in Brazil. C. bainae appears to be highly diffused in dog populations in southern Europe. The phylogenetic analyses based on cox1 and 12S do not reveal the three species of Cercopithifilaria parasitizing dogs as a monophyletic group, which suggests that they have derived independently by host switching.