Aphyocharax rathbuni Eigenmann, 1907

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, pp. 1-9 : 2-3

Aphyocharax rathbuni Eigenmann, 1907

figs. 1,2

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. 2021b).

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.

Figures

fig. 7 Distribution map of the recorded species: yellow = Aphyocharax rathbuni; green = Oligosarcus robustus; red = Psalidodon erythropterus; blue = Pseudocorynopoma stanleyi. Triangles = records from Uruguay; circles = records from outside Uruguay based on literature. Py. = Paraguay; Uy. = Uruguay.