A new Physaloptera (Nematoda: Physalopteridae) parasite of Tupinambis merianae (Squamata: Teiidae) from southeastern Brazil.

Physaloptera tupinambae n. sp. (Nematoda: Physalopteridae) collected from the stomach of 1 Tupinambis merianae (Squamata: Teiidae) male lizard is described. Physaloptera tupinambae, which belongs to the didelphys group, is the only species in the genus that exhibits a bipartite internal tooth and in which the excretory pore is anterior to the deirids. The new species can be differentiated from the other congeners mainly based on the number and pattern of caudal papillae and the length and shape of spicules. Physaloptera murisbrasiliensis and Physaloptera clausa orientalis are the only physalopterids with the same number of caudal papillae as for P. tupinambae, but they differ from the new species mainly in length and shape of spicules. Based on morphological analysis, the speciation process among Physaloptera probably occurred via host capture, and P. tupinambae occupies an intermediate phylogenetic position in the genus. Most likely, the new parasite was acquired by the lizard through ingestion of an intermediate host. Finally, Physaloptera calotisi, Physaloptera funambuli, Physaloptera guptae, Physaloptera indica, Physaloptera johnsoni, Physaloptera kherai, and Physaloptera thaparus are moved to Abbreviata.