In addition, the sex-ratio referred to by Fern´andez-Delgado & Herrera (1995) and Soriguer et al. (2000) for S. pyrenaicus (1 ♀: 1 ♂) reveals an equilibrium between sexes in contrast with the 2.38 ♂: ♀ found in the Estor˜aos River for S. carolitertii.