Three new South American mailed catfishes of the genera Rineloricaria and Loricariichthys (Pisces, Siluriformes, Loricariide)

Three new species belonging to two different genera of South American mailed catfishes of the subfamily Loricariinae are described and figured. A discussion of and comparative notes on related species are added. Rineloricaria formosa n. sp. is described from the Río Inírida/Río Orinoco drainage in Colombia, from the Río Atabapo (Río Orinoco drainage) in Venezuela, and from the Rio Tiquié and Rio Uaupés (Rio Amazonas drainage) in Brazil. It is compared with Rineloricaria morrowi Fowler, 1940, with Rineloricaria melini (Schindler, 1959), and with Rineloricaria fallax (Steindachner, 1915). The lectotype of the latter species is herein designated, and a discussion on the misidentification of R. fallax with Loricariichthys brunneus (Hancock, 1828) is added. Rineloricaria hasemani n. sp. is based on three specimens, two of which are paralectotypes of Rineloricaria fallax from Maguarý. The specimens were collected from streams around Belém, Est. Pará, Brazil. This new species seems more closely related to Rineloricaria stewarti (C. H. Eigenmann, 1909) than to R. fallax. Loricariichthys platymetopon n. sp. is based upon several specimens found in the Río Paraná/Río Paraguay system and in the Rio Uruguay, and upon one specimen collected from near the Rio Solimões. This species has hitherto erroneously been recorded as Loricaria maculata by Valenciennes (1840, 1847) and by Boulenger (1896), as Loricariichthys maculatus by Lüling (1975), and as Loricaria typus (in subgenus Loricariichthys) by Regan (1904) and by A. de Miranda Ribeiro (1918). It seems likely that previous records of these nominal species (particularly from the Paraná/Paraguay basin) actually concern, at least in part, L. platymetopon. This is confirmed for two specimens from the Rio Uruguay. L. platymetopon is compared with Loricariichthys maculatus (Bloch, 1794) — of which Parahemiodon typus Bleeker, 1862, provisionally is considered a junior synonym — and with Loricariichthys ucayalensis Regan, 1913, the lectotype of which is herein designated from the two syntypes.