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The nematode family Spirocercidae Chitwood and Wehr, 1932, comprises three subfamilies, Spirocercinae Chitwood and Wehr, 1932; Ascaropsinae Alicata and McIntosh, 1933; and Mastophorinae Quentin, 1970, which occur worldwide. Spirocercids infect canids and can cause severe illness. The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), is a canid that inhabits most of South America, including Brazil and is a host for several parasitic worms, in particular, nematodes. However, few reports or genetic data are available on the spirocercids found in this host. In the present study, we describe a new species of Spirobakerus Chabaud and Bain 1981, from the intestine of two crab-eating foxes from two different biomes in Brazil. Spirobakerus sagittalis sp. nov. presents a) unequal spicules, with a long, thin left spicule with a lanceolated shape at the tip; b) a pair of sessile papillae and a median unpaired papillae located anteriorly of the cloaca, and c) a tuft without spines at the tip of the tail in females. The molecular phylogenetic analysis indicated that S. sagittalis sp. nov. is basal to the other species of the subfamily Ascaropsinae, which was not recovered as monophyletic. Our phylogenies also indicated that Spirocercidae is paraphyletic, given that Mastophorinae did not group with Ascaropsinae and Spirocercinae. We provide the first molecular data on the genus Spirobakerus and expand the molecular database of the spirocercids. However, further studies, including the sequences of other spirocercid taxa, are still needed to infer the relationships within this family more accurately.

Gigantorhynchus echinodiscus (Diesing, 1851) is a parasite of anteaters in South America. Although described by Diesing in 1851, there is still a lack of taxonomic and phylogenetic information regarding this species. In the present study, we redescribe G. echinodiscus collected from a giant anteater, Myrmecophaga tridactyla Linnaeus, 1758, from the Brazilian Cerrado (Savannah) in the State of São Paulo by light and scanning electron microscopy. In addition, phylogenies were inferred from partial DNA gene sequence of the nuclear large subunit ribosomal RNA gene (28S rRNA). We provide for the first time details of the proboscis with a crown having 18 large hooks and numerous small hooks, a lateral papilla at the base of the proboscis, a ringed pseudo-segmented body, large testes, cemented glands in pairs, and a non-segmented region in the posterior end of the body, which contributed to the diagnosis of the species. Molecular phylogenetic analyses recovered G. echinodiscus forming a well-supported monophyletic group with Mediorhynchus sp., which was congruent with morphological studies that allocate both genera within the family Gigantorhynchidae. In conclusion, the present work adds new morphological and molecular information, emphasizing the importance of adopting integrative taxonomic approaches in studies of Acanthocephala., Competing Interests: On behalf of the authors, all the authors disclose any financial interest, personal relationship with other people or organizations and commercial sponsor for this work which could inappropriately influence the work and causes conflict of interest., (© 2019 The Authors.)