Hisonotus ringueleti Aquino, Schaefer & Miquelarena, 2001

Carvalho, Tiago P. & Reis, Roberto E., 2009, Four new species of Hisonotus (Siluriformes: Loricariidae) from the upper rio Uruguay, southeastern South America, with a review of the genus in the rio Uruguay basin, Zootaxa 2113 (1), pp. 1-40 : 31-34

Hisonotus ringueleti Aquino, Schaefer & Miquelarena, 2001

( Figures 19–20 , Table 7)

Hisonotus ringueleti Aquino, Schaefer & Miquelarena, 2001:1–12 , (type locality: Uruguay, Rivera, creek at km 18 of route joining Santana do Livramento , Brazil, and Rivera, Uruguay).

Hisonotus candombe Casciotta, Azpelicueta, Almirón & Litz, 2006:147–152 , (type locality: Uruguay, Departamento Salto, río Uruguay basin, arroyo Palomas – New synonym).

Material examined. All from rio Uruguai basin: Rio Quaraí drainage: ILPLA 886, holotype, 35.4 mm SL, Uruguay, Rivera, creek at km 18 of route joining Santana do Livramento, Brazil, and Riveira, Uruguay, close to border, tributary to rio Quaraí drainage (ca. 31°00’ S 55°30’W). ILPLA 883, paratypes, 95, 24.2–35.4 mm SL; ANSP 177878, paratypes, 3 + 1 c&s, 22.8–31.3 mm SL; MCP 26154, paratypes, 3 + 1 c&s, 22.6–32.1 mm SL; and MLP 9536, 4, 27.2–34.1 mm SL; collected with the holotype. AI 187, paratypes of H. candombe , 3, 23.6–29.2 mm SL, Uruguay, Artigas, arroyo Catalán Grande, 30°50’35”S 56°14’30”W. MCP 11215, 128 + 4 c&s 13.5–38.4 mm SL, Brazil, Quaraí, arroio Quaraí-Mirim on road between Quaraí and Alegrete, 30°18’S 56°19’W. MCP 35239, 1, 39.4 mm SL, Brazil, Quaraí, arroio Quaraí-Mirim on road from Quaraí to Baltazar Brum train station about 20 km northeast from Quaraí, 30°14’38”S 56°18’23”W. UFRGS 4208, 1, 31.9 mm SL, Brazil, Uruguaiana, sanga Mergulhão tributary of arroio Garupá on highway BR-290. UFRGS 7763, 3, 19.7–38.3 mm SL, Uruguay, Artigas, arroyo Cuaró Grande on ruta 4, 30°46’57”S 56°46’47”W. Rio Ibicuí drainage: MCN 11383, 2, 35.5–37.7 mm SL, Brazil, Alegrete, sanga do Lagoão about 20 km south of Alegrete, tributary of arroio Pai-Passo, tributary of rio Ibirapuitã, MCP 11373, 3, 13.6–18.8 mm SL, Brazil, Quaraí, arroio Pai-Passo on highway RS-185 between Alegrete and Santana do Livramento, 30°13’S 56°02’W. MCP 27659, 1, 36.8 mm SL, Brazil, Tupaciretã, rio Santana near to locality of Jari, tributary to rio Jaguari, 29°14’33”S 54°16’47”W. Río Arapey Grande drainage: ZVC-P 5595, holotype of Hisonotus candombe , 28.7 mm SL, Uruguay, Salto, Arroyo Palomas, 31°04’43S 57°37’26”W. ZSM 32062, paratype of H. candombe , 1, 25.9 mm SL; AI 164, paratype of H. candombe , 25.5 mm SL; and MHNG 2662.86, paratype of H. candombe , 1, 26.3 mm SL, collected with the holotype. UFRGS 8029, 1, 26.3 mm SL, Uruguay, Salto, creek tributary to Río Arapey Grande on ruta 4. Other drainages of Río Uruguay: UFRGS 7976, 3, 32.3–40.8 mm SL, Uruguay, Artigas, arroyo Guaviyú on ruta 3, 30°38’S 57°41’W. UFRGS 8064, 3, 29.9–43.4 mm SL, Uruguay, Artigas, arroyo Mandiyú on ruta 3, 30°51’S 57°39’W. UFRGS 8573, 3, 33.5–40.6 mm SL, Uruguay, Salto, arroyo del Tala on ruta 31 between Artigas and Salto, 31°23’S 57°33’W.

Remarks on synonymy. Examination of the type-series of Hisonotus candombe did not reaveal any consistent differences between the later and Hisonotus ringueleti ( Fig.19–20 ). According to Casciotta et al. (2006, p.150) H. candombe differs from H. ringueleti in having larger pectoral spine serrae distributed all along the posterior margin of the pectoral spine vs. serrae smaller and placed on distal two thirds of the spine. Besides that, H. candombe could be distinguished from H. ringueleti by having five branched anal-fin rays and males with a smaller flap on first pelvic-fin unbranched ray, whereas H. ringueleti supposedly presents four anal-fin rays and a well developed flap. A disapeareance of the pectoral-fin spine serrae in the ontogeny of specimens of H. ringueleti was observed. Smaller individuals of that species present strong serrations on the posterior portion of pectoral spine, decreasing in size with the development, being totally absent at about 35 mm SL ( Fig. 21 ). A similar disapearence of serrae in adults occurs in several other congeners. Since specimens used in the description of H. candombe are relatively small (range size 22.8–30.0 mm in SL) compared to the range of the species (up to 43 mm in SL), that difference seems to be due to the degree of ontogenetic development. In the same manner, a smaller pelvic flap in males of H. candombe is related with the maturity of the individuals, and not useful to diagnose the species. Lastly, the anal-fin ray count is identical in both nominal species. The description of Aquino et al. (2001, tab.1) of four branched anal-fin rays for H. ringueleti seems to be an error, since from 30 paratypes examined only one specimen presented four branched anal-fin rays, all remaining having five. Fin-ray counts do not vary considerably within or among species of Hisonotus , and are not useful to distinguish species. Therefore H. candombe is considered a junior synonym of H. ringueleti .

Remarks on type-locality. Hisonotus ringueleti was described from a single locality on the rio Uruguay basin ( Aquino et al., 2001). The type-locality is a creek tributary to the rio Quaraí at km 18 of route joining Santana do Livramento, Brazil and Rivera, Uruguay (ca. 31°00’S 55°30’W). However, the cities of Rivera and Santana do Livramento are contiguous and only divided by an avenue, without a route of 18 km between them. These cities are surrounded by the headwaters of three large drainages, rio Negro, rio Quaraí, and rio Ibicuí, all tributaries to the rio Uruguay basin. The approximate coordinates (ca. 31°00’ S 55°30’W) as well as all localities at about 18 km from Rivera in Uruguay are situated in the río Negro drainage. However, Hisonotus ringueleti was not found in that drainage. The headwaters of rio Quaraí drainage, nearby Santana do Livramento/ Rivera were located in the Brazilian territory, or in the Departmento of Artigas in Uruguay which seems the most probable type-locality of Hisonotus ringueleti .

Figures

FIGURE 19. Hisonotus ringueleti, MCP 11215, female, 37.0 mm SL. Arroio Quaraí-Mirim on road between Quaraí and Alegrete, Quaraí, Rio Grande do Sul, Brazil.

FIGURE 20. Juvenile specimens of Hisonotus ringueleti. A—ILPLA 883, paratype of H. ringueleti, 23.9 mm SL. Creek at km 18 of route joining Santana do Livramento and Rivera, rio Quaraí drainage, Rivera, Uruguay. B—MHNG 2662:86, paratype of H. candombe, 26.3 mm SL. Arroyo Palomas, Río Arapey Grande drainage, Salto, Uruguay.

FIGURE 21. Left pectoral-fin spine of Hisonotus ringueleti in dorsal view.A—MCP 11215, 38.1 mm SL. B—MCP 11215, 31.2 mm SL. Scale bar is 2mm.