On the rugose area and caudal papillae distribution in Dirofilaria immitis (Leidy, 1856) Railliet & Henry, 1911, by scanning electron microscopy.

The objective of this study was to obtain a better characterization of Dirofilaria immitis (Leidy, 1856) Railliet & Henry, 1911, in Brazil, ratifying previous accounts and adding new data on the rugose area on the ventral surface of the spiralled posterior portion of males observed by scanning electron microscopy, which presents a different arrangement compared to other species of the genus, and differs also from the genera Litomosoides Chandler, 1931, and Wuchereria Silva Araújo, 1877, adding another taxonomic character to Dirofilariinae and Onchocercinae. Scanning electron microscopy studies also showed some aspects of the distribution of caudal papillae in D. immitis that have not been described before.