Designation of a lectotype for Deuterodon pedri Eigenmann, 1908 (Characiformes: Characidae).

Deuterodon pedri was briefly described in 1908 by Carl Eigenmann on the basis of seven specimens of 73–100 mm standard length (SL), all "in very poor condition" according to the author. In the original description, Eigenmann did not mention the location where the specimens were captured, even though the publication presented results of the Thayer expedition to Brazil (Eigenmann 1908: 93). Eigenmann (1927:348) later redescribed the species, adding new data, and indicated the seven specimens as Cotypes (=syntypes) (MCZ 21081), all collected during the Thayer Expedition in "Rio San Antonio, Santa Anna de Ferros" (currently Ferros, Minas Gerais, Doce River basin). Both Eschemeyer (2012) and the database of the Museum of Comparative Zoology collection of fishes (http://mczbase.mcz.harvard.edu/guid/MCZ:Fish:21081) indicate five syntypes instead of the seven originally noted. We had the opportunity to examine two (58.7 mm and 78.4 mm SL) of these five specimens and found that they represent distinct species, readily distinguishable by the shape of the cusps on premaxillary teeth and the way in which the dentary teeth decrease in size. These two traits are mentioned in the redescription of the species by Eigenmann (1927) and are present in the 78.4 mm SL specimen: "the denticles [=cusps] [of] the second row of teeth [are] in a slight crescent" and "dentary with about ten teeth graduated from the minute lateral teeth to the large first tooth." However, these traits are different in the smaller specimen (58.7 mm SL), in which the premaxillary inner row teeth are straight and dentary teeth decrease abruptly as of the fifth tooth. Furthermore, this specimen has tricuspid premaxillary teeth on the outer series and quadrito pentacuspid teeth on the inner series; among the dentary teeth, the first five are pentacuspid, the sixth quadricuspid, the seventh triscupid and eighth bicuspid (vs. premaxillary teeth on outer series pentacuspid, the first tooth of the inner series pentacuspid, the other four hexato heptacuspid, and the dentary teeth hexato heptacuspid in the specimen of 78.4 mm SL). We did not examine the other three syntype specimens (also in very poor condition), but to establish the application of the name Deuterodon pedri the 78.4 mm SL specimen is designated here as lectotype. Consequently, the other four specimens are paralectotypes (and remain unidentified). A redescription of the species is urgently needed due to the poor condition of the types.