On Hemiodontichthys acipenserinus and Reganella depressa, two remarkable Mailed Catfishes from South America (Pisces, Siluriformes, Loricariidae)

Hemiodontichthys acipenserinus (Kner, 1854) is redescribed and figured after examination of 132 specimens from the Rio Amazonas, Essequibo River, and Rio Paraguai systems, including five syntypes, from which the lectotype is selected. Reganella depressa (Kner, 1854) is redescribed and figured after examination of 7 specimens from the Rio Amazonas system, including two syntypes, from which the lectotype is selected. Relationships of the monotypic genera Hemiodontichthys Bleeker, 1862, and Reganella Eigenmann, 1905 with other genera are briefly discussed.