Description of a new species of Auriculostoma (Digenea: Allocreadiidae) from Characidium heirmostigmata (Characiformes: Crenuchidae) from Argentina, using morphological and molecular data.

During a parasitological survey of fishes at Iguazu National Park, Argentina, specimens belonging to the allocreadiid genus Auriculostoma were collected from the intestine of Characidium heirmostigmata. The erection of the new species is based on a unique combination of morphological traits as well as on phylogenetic analysis. Auriculostoma guacurarii n. sp. resembles four congeneric species - Auriculostoma diagonale, Auriculostoma platense, Auriculostoma tica and Auriculostoma totonacapanensis - in having smooth and oblique testes, but can be distinguished by a combination of several morphological features, hosts association and geographic distribution. Morphologically, the new species can be distinguished from both A. diagonale and A. platense by the egg size (bigger in the first and smaller in the last); from A. tica by a shorter body length, the genital pore position and the extension of the caeca; and from A. totonacapanensis by the size of the oral and ventral sucker and the post-testicular space. Additionally, one specimen of Auriculostoma cf. stenopteri from the characid Charax stenopterus (Characiformes) from La Plata River, Argentina, was sampled and the partial 28S rRNA gene was sequenced. The phylogenetic analysis revealed that A. guacurarii n. sp. clustered with A. tica and these two as sister taxa to A. cf. stenopteri. The new species described herein is the tenth species in the genus and the first one parasitizing a member of the family Crenuchidae.

A new species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the upper rio Paraná basin, Brazil

A new species of Corydoras is described from three tributaries of the rio Ivaí drainage, upper rio Paraná basin, Paraná State, Brazil. The new species can be distinguished from most of its congeners by the presence of three nasal pores. Other diagnostic features are the lower number of serrations in posterior margin of pectoral and dorsal spines and presence of four to six small black blotches along the midline of the flank. The possible mimetic relationship between the new species and Characidium heirmostigmata is discussed. Uma espécie nova de Corydoras é descrita de três tributários da drenagem do rio Ivaí, bacia do alto rio Paraná, estado do Paraná, Brasil. A espécie nova se diferencia da maioria de suas congêneres por apresentar três poros nasais. Outras características diagnósticas são o menor número de serrilhas na margem posterior dos espinhos peitoral e dorsal e presença de quatro a seis manchas pretas pequenas ao longo da linha mediana do flanco. A possível relação mimética entre a espécie nova e Characidium heirmostigmata é discutida.