taxonID	type	description	language	source
DD1187F3FFF7FFCCFF28FD7BFE72F34E.taxon	materials_examined	Examined material: Uruguay: Artigas: MHNM 4431, 2 ex., 28.7 - 29.5 mm SL, Rincón de Franquia, aprox. 30 ° 12 ' S 57 ° 34 ' W, col. M. Caligari & E. Caligari, 16 / I / 2019; MHNM 4434, 1 ex, 27.2 mm SL, Rincón de Franquia, 30 ° 13 ' 42 " S 57 ° 36 ' 58 " W, col. G. Sanguinetti & N. Power, 23 / II / 2020; MHNM 4792, 3 ex, 22.5 - 25.6 mm SL, Rincón de Franquia, 30 ° 13 ' 42 " S 57 ° 36 ' 58 " W, col. W. S. Serra, G. Sanguinetti, M. García, M. Caligari, G. Núñez & G. Sosa, 31 / X / 2021; MHNM 4794, 7 ex, 22.4 - 25.5 mm SL, Rincón de Franquia, 30 ° 13 ' 42 " S 57 ° 36 ' 58 " W, col. W. S. Serra, G. Sanguinetti, M. García, M. Caligari, G. Núñez & G. Sosa, 31 / X / 2021. This species differs from other congeners of the genus by the following combination of characters: adipose fin and base of caudal and anal fins red, pelvic, pectoral and dorsal fins without red coloration, absence of black or dark brown coloration on middle caudal-fin rays, red coloration on the posterior region of the body not extended dorsal to the lateral midline of the body, 4 - 5 premaxillary and 1 - 3 maxillary tooth, 19 - 21 anal fin rays and lateral line incomplete with 6 - 8 perforated scales (Steindachner 1882; Fowler 1940; Gery 1977; Britski et al. 1999; Willink et al. 2003; Almirón et al. 2015; Terán et al. 2016; Brito et al. 2018). The specimens herein reported present all these characters and come from northern Uruguay, associated to the Uruguay River and one of its affluents, the Cuareim River (fig. 7). The species was collected in canals and wetlands, where it appears to be very scarce, forming schools with Aphyocharax anisitsi Eigenmann & Kennedy, 1903. The previously known distribution of A. rathbuni extended through Paraná, Paraguay and Mamoré River basins, in Argentina, Bolivia, Brazil and Paraguay (Britski et al. 1999; Hablützel 2012; Fricke et al. 2021 b). Aphyocharax rathbuni has been informally mentioned for Uruguay for at least nine years (oldest publication date in Google Search: 28. mar. 2012), with numerous aquarium blogs and websites repeating the text “ endémique du bassin du Rio Paraguay au Paraguay, du fleuve Paraná en Uruguay, au Brésil, et en Argentine ” (Aquaportail) in different languages, but none of these sites mentions the source of that information. The Fishbase website (2021) in their “ Point map ” tool of the “ Species Summary ”, points out eight Uruguayan records mined from Gbif. org, which mined the data from the ichthyological database of the “ Swedish Museum of Natural History ”. The records of this last database are from nine geographical points in Uruguay and Cuareim river basins in Salto and Artigas departments with one to 13 specimens each one, none of them published in scientific journals yet. Curiously, only four lots of A. anisitsi, all from Salto, were accessed from the same expeditions, while our observations in situ indicates that A. anisitsi is extremely abundant in all northern Uruguayan area, making those identifications of A. rathbuni doubtful. Nión et al. (2016) mentioned A. rathbuni in their book “ Peces del Uruguay: Lista sistemática y nombres comunes ”, probably based on these records but without any information about sources or vouchers. In social media (“ Peces Argentinos ” Facebook’s group) some photos of the species taken in northern Uruguay, were posted by aquarium hobbyist in the last two years (fig. 2), showing its highly probable presence in the country. The specimens here analyzed confirm with vouchers the presence of A. rathbuni for Uruguay and Uruguay River basin.	en	Serra, Wilson S., Scarabino, Fabrizio, Furtado, Giovanni, Sanguinetti, Germán, Caligari, Mauricio (2021): Fighting faunistic chaos: confirmations and new records for Uruguayan Characidae (Ostariophysi: Characiformes). Ichthyological Contributions of PecesCriollos 77: 1-9, DOI: 10.5281/zenodo.17001646
DD1187F3FFF4FFCCFF28FC83FDAEF6CD.taxon	materials_examined	Examined material: Uruguay: Cerro Largo: MHNM 4429, 2 ex., 109.0 - 124.5 mm SL, Río Yaguarón, 32 ° 31 ' 01 " S 53 ° 27 ' 27 " W, col. W. S. Serra, G. Furtado & A. Balao, 30 - 31 / III / 2018; MHNM 4430, 1 ex., 91.8 mm SL, Cañada de las Pajas, Paso de las Mercedes, 32 ° 30 ' 34 " S 53 ° 31 ' 04 " W, col. W. S. Serra, G. Furtado & A. Balao, 1 / IV / 2018. Treinta y Tres: MHNM 4427, 1 ex., 87.2 mm SL, Laguna Arnaud, 33 ° 15 ' 00 " S 54 ° 22 ' 55 " W. This species differs from other congeners of the genus by the following combination of characters: 16 - 18 transverse scale rows above lateral line, 75 - 85 perforated scales in the lateral series, 28 - 32 horizontal scale rows around caudal peduncle, maxillary, premaxillary and dentary teeth unicuspidate and tip of pectoral fins surpassing the origin of pelvic fins (Menezes 1969; Menezes & Ribeiro 2015; Ribeiro & Menezes 2015). Analyzed specimens present all these characters and come from eastern and northeastern Uruguay, associated to the Merín Lagoon basin (fig. 7). The previously known distribution of O. robustus extended through Patos-Merin Lagoon basin and Tramandaí system in Rio Grande do Sul, Brazil (Ribeiro & Menezes 2015). The species was first recorded for the country by Menezes (1969), who analyzed three specimens (MZUSP [ex DZSASP] 4679 to 4681, paratypes) from Salto Chico (Salto Department). Menezes (1987: 29) redetermined these lots as Oligosarcus oligolepis (Steindachner, 1867), an extremely similar species distributed in La Plata, Uruguay, Paraguay and lower Paraná river basins (Fricke et al. 2021 b). Teixeira de Mello et al. (2005) mentioned O. robustus as a new record for Uruguay in a congress abstract, but they did not provide any information about vouchers or precise localities. Aside from these, Soutullo et al. (2009) mentioned it in a technical report as a conservation priority for the SNAP (Sistema Nacional de Áreas Protegidas), but lacking distributional or voucher data. In later versions of the list (Loureiro et al. 2013) the species was not included. The specimens here analyzed confirm with vouchers the presence of O. robustus for the Uruguayan territory.	en	Serra, Wilson S., Scarabino, Fabrizio, Furtado, Giovanni, Sanguinetti, Germán, Caligari, Mauricio (2021): Fighting faunistic chaos: confirmations and new records for Uruguayan Characidae (Ostariophysi: Characiformes). Ichthyological Contributions of PecesCriollos 77: 1-9, DOI: 10.5281/zenodo.17001646
DD1187F3FFF4FFCDFF28F900FCDFF4B5.taxon	materials_examined	Examined material: Uruguay: Colonia: MHNM 3922, 2 ex, 64.2 - 74.3 mm SL, Nueva Palmira, aprox. 33 ° 52 ' S 58 ° 25 ' W, col. CARU-CARP, 5 / VI / 2016. San José: MHNM 3501, 1 ex., 63.7 mm SL, mouth of Arroyo Mauricio, 34 ° 42 ' 28 " S 56 ° 41 ' 42 " W, col. W. S. Serra, 28 / III / 2014. Soriano: MHNM 3909, 2 ex. 67.5 - 73.3 mm SL, Uruguay River between La Concordia and La Agraciada, col. CARU-CARP, 3 / VI / 2016. This species differs from other congeners from the La Plata River and Patos-Merin Lagoon basins by the following combination of characters: 11 - 13 transverse scale rows above lateral line, 49 - 54 perforated scales in the lateral series and one maxillary tooth with 5 or 7 cusps (Soneira et al. 2010). The analyzed specimens present all these characters and come from southwestern Uruguay, associated to the La Plata and Uruguay rivers (fig. 7). The previously known distribution of P. erythropterus extended through Paraguay, lower Paraná and La Plata River basins in Argentina and Paraguay (Holmberg 1891; Soneira et al. 2010; Insaurralde et al. 2012). Psalidodon erythropterus was first mentioned (as Astyanax erythropterus) and illustrated for Uruguay River area in a technical report published by the Comisión Administradora del Río de la Plata and the Comisión Administradora del Río Uruguay (CARP-CARU 2016), where the authors comment that the species “ has yet to be formally recorded as part of the Uruguayan fauna ”. Specimens mentioned in that report (MHNM 3909 and MHNM 3922) are incorporated as part of the present work. Moreover, another report (López-Rodríguez et al. 2019) lists one specimen from Uruguay River in Río Negro Department, collected in autumn 2019, but lacking any other data. Our examination of the specimens mentioned in the first report plus one specimen from San José Department, confirm the presence of P. erythropterus for the Uruguayan territory. fig. 3 Oligosarcus robustus before and after fixation: MHNM 4430, 91.8 mm SL, Cañada de las Pajas, Paso de las Mercedes, 32 ° 30 ' 34 " S 53 ° 31 ' 04 " W, Cerro Largo, Uruguay fig. 4 Psalidodon erythropterus before and after fixation: MHNM 3501, 63.7 mm SL, mouth of Arroyo Mauricio, 34 ° 42 ' 28 " S 56 ° 41 ' 42 " W, San José, Uruguay. Upper picture flipped.	en	Serra, Wilson S., Scarabino, Fabrizio, Furtado, Giovanni, Sanguinetti, Germán, Caligari, Mauricio (2021): Fighting faunistic chaos: confirmations and new records for Uruguayan Characidae (Ostariophysi: Characiformes). Ichthyological Contributions of PecesCriollos 77: 1-9, DOI: 10.5281/zenodo.17001646
DD1187F3FFF5FFCAFF28FAD9FEDBF227.taxon	description	figs. 5, 6 Examined material: Uruguay: Cerro Largo: MHNM 1024, 1 ex., 44.3 mm SL, Arroyo Corrales, 33 ° 01 ' 33 " S 54 ° 06 ' 47 " W, E. Messner, 27 / I / 1962; MHNM 1075, 3 ex., 32.3 - 45.5 mm SL, cañada cerca de Arroyo Coronilla, al sur de Río Branco, aprox. 32 ° 36 ' 07 " S 53 ° 20 ' 48 " W, col. E. Messner, 15 / IV / 1962; MHNM 1090, 2 ex., 48.6 - 51.9 mm SL, cañada en Camino entre Río Branco y Dragón, col. E. Messner, 16 / IV / 1962; MHNM 4368, 1 ex., 51.2 mm SL, Paso Sarandí, 32 ° 26 ' 25 " S 53 ° 36 ' 46 " W, Arroyo Sarandí de Barceló, col. W. S. Serra, G. Furtado & A. Balao, 1 / IV / 2018; MHNM 4428, 1 ex., 51.2 mm SL, Río Yaguarón, 32 ° 31 ' 01 " S 53 ° 27 ' 27 " W, col. W. S. Serra, G. Furtado & A. Balao, 30 - 31 / III / 2018. Lavalleja: MHNM 2745, 1 ex., 50.3 mm SL, Arroyo Polanco, 33 ° 52 ' 07 " S 55 ° 07 ' 11 " W, col. L. H. Amato, 25 / X / 1980; MHNM 4418, 1 ex., 37.5 mm SL, Arroyo Polanco, 33 ° 52 ' 07 " S 55 ° 07 ' 11 " W, 1981. Rocha. MHNM 928, 8 ex., 43.8 - 50.3 mm SL, Ruta 16, “ 2 ° arroyo que cruza la carretera (Castillos) ”, aprox. 34 ° 09 ' S 53 ° 50 ' W, col. E. Messner; MHNM 932, 1 ex., 52.4 mm SL, Ruta 16, “ 2 ° arroyo que cruza la carretera (Castillos) ”, aprox. 34 ° 09 ' S 53 ° 50 ' W, col. E. Messner; MHNM 1307, 2 ex., 39.6 - 41.9 mm SL, afluente de Laguna Negra, cruza Camino de los Indios, aprox. 33 ° 54 ' S 53 ° 43 ' W, col. E. Messner, 9 / IX / 1962. MHNM 2743, 1 ex., 35.5 mm SL, Arroyo del Pescado, 33 ° 58 ' 24 " S 53 ° 45 ' 04 " W, col. E. Messner; MHNM 2747, 4 ex., 45.5 - 68.1 mm SL, Playa de la Angostura, Laguna Negra, aprox. 34 ° 04 ' S 53 ° 38 ' W, col. Skuk, Rodríguez & Amato, 20 / I / 1982; MHNM 4424, 1 ex., 34.3 mm SL, nameless stream, 34 ° 09 ' 41 " S 53 ° 50 ' 27 " W, col. W. S. Serra & G. Furtado, 17 / XII / 2020; MHNM 4425, 3 ex., 52.0 - 56.1 mm SL, Paso del Bañado, Ruta 16 km 18.400, 34 ° 07 ' 37 " S 53 ° 50 ' 18 " W, col. W. S. Serra & G. Furtado, 17 / XII / 2020; MHNM 4426, 4 ex., 26.6 - 54.2 mm SL, Paso del Bañado, Ruta 16 km 18.400, 34 ° 07 ' 37 " S 53 ° 50 ' 18 " W, col. W. S. Serra & G. Furtado, 17 / XII / 2020. Treinta y Tres: MHNM 1039, 1 ex., 52.8 mm SL, “ A ° Malo, A ° Yerbal y otro de Río Olimar Grande ”, aprox. 33 ° S 54 ° W, col. E. Messner. This species differs from other congeners of the genus by the following combination of characters: 32 - 36 branched anal fin rays, presence of an intermediate lobe in the distal margin of the anal fin of males, and males with absence of black spots at the distal tip of the pectoral fin and the tip of the anterior lobe of the anal fin (Malabarba et al. 2020). Specimens analyzed present all these characters and come from eastern and northeastern Uruguay, associated to Merín Lagoon basin (fig. 7). The previously known distribution of P. stanleyi extended through Patos-Merin Lagoon basin and Tramandaí system in Rio Grande do Sul, Brazil (Malabarba, et al. 2020). Described in late 2020 and recorded with numerous lots from all Patos-Merin Lagoon basin in Rio Grande do Sul, P. stanleyi was expected to also be present in the Uruguayan region of the same basin, especially considering published records (Azpelicueta & García 2001; Serra et al. 2020) and numerous photographs from social media (“ Peces Argentinos ” Facebook’s group, e. g. Figure 6) of “ Pseudocorynopoma doriae ” from this area. Specimens here analyzed confirm with vouchers the presence of the species for Uruguayan territory.	en	Serra, Wilson S., Scarabino, Fabrizio, Furtado, Giovanni, Sanguinetti, Germán, Caligari, Mauricio (2021): Fighting faunistic chaos: confirmations and new records for Uruguayan Characidae (Ostariophysi: Characiformes). Ichthyological Contributions of PecesCriollos 77: 1-9, DOI: 10.5281/zenodo.17001646
