Gongylonema Parasites of Rodents: A Key to Species and New Data on Gongylonema neoplasticum.

Specimens of the genus Gongylonema were collected from the gastric mucosa of rodents of Rattus rattus Linnaeus, 1758, and Rattus norvegicus Berkenhout, 1769, collected in urban areas in Belém, Pará, in the eastern Brazilian Amazon. The helminths were processed for analysis using light microscopy and scanning electron microscopy (SEM) techniques and presented taxonomic characteristics of the species Gongylonema neoplasticum. The SEM analyses revealed the presence of 2 developed buccal plates (1 dorsal, 1 ventral), also called interlabia, with a prominent and bifurcated ventral plaque. The occurrence of the bifurcated ventral interlabium had not yet been identified by any other author from G. neoplasticum. As a result of our extensive research on published data on Gongylonema spp., we propose a taxonomic key for species of this genus that parasitize rodents. This is the first record of G. neoplasticum in urban areas of the Brazilian Amazon.