A NEW SPECIES OF RHABDOCHONA RAILLIET, 1916 (NEMATODA, RHABDOCHONIDAE) FROM ENDEMIC GOODEIDS (CYPRINODONTIFORMES) FROM 2 MEXICAN LAKES

A new species of Rhabdochona from 2 species of freshwater fishes, Allo ophorus robustus and Goodea. atripinnis, is described from 2 lakes of the Mesa Central of Mexico. Rhabdochona lichtenfelsi n. sp. belongs to a group of species possessing inconspicuous bifurcated deirids and a prostom armed with 10 large teeth. It is distinguished from them becau se the left spicule is shorter, the tip is bifurcate, and both spicule s lack a reflected dorsal barb. The new species most closely resembles Rhabdochona catostomi and Rhabdochona milleri but differs from them b ecause the former possesses a left spicule tip with ventral barb, righ t spicule with reflected distal barb, and 5 pairs of postanal papillae , whereas R. milleri has 14 prostomal teeth, eggs rounded, and left sp icule with slightly outlined bifurcation and right with a dorsal barb. Previous records of R. milleri in Mexico must be referred to R. licht enfelsi.