Serrapinnus calliurus

Serrapinnus calliurus (Boulenger, 1900) (fig. 1)

o Cheirodon calliurus Boulenger, 1900 *: 3 [description]

o Cheirodon piaba (partim): Carrera, 1976: 37 [species list]. NON Chirodon piaba Lütken, 1875

o Serrapinnus piaba: Reichert, 2002: 28, 114 [drawing and brief description of coloration]. NON Chirodon piaba Lütken, 1875

o Serrapinnus piaba (partim): Nión et al., 2002: 12 [species list]; Nión et al., 2016: 29, 73, 132 [species list]. NON Chirodon piaba Lütken, 1875

o Serrapinnus calliurus: Malabarba, 1998 *: 215 [new combination]; Malabarba, 2003: 219 [catalog]; Miquelarena et al., 2008: 73 [identification key, redescription and distribution]; Litz & Koerber, 2014: 12 [species list]; Mantinian, 2011 *: 50, 93 [identification key, redescription, pictures and distribution]

o Serrapinnus sp. (partim): Loureiro et al., 2013: 104, 110 [species list and conservation]

Examined material (18 lots): MHNM 984, 3 ex., 30,2-33,0 mm SL, Laguna de las Lavanderas (30°24'52''S; 56°26'49"W), Artigas, Artigas Department, Uruguay, col.: E. Messner, 10/I/1962. MHNM 1207, 4 ex., 29,3-32,5 mm SL, Laguna de las Lavanderas (30°24'52''S; 56°26'49"W), Artigas, Artigas Department, Uruguay. MHNM 3783, 19 ex., 13,9-29,8 mm SL (1ex. 20,9 mm SL fixed in 95% Ethanol), Paso de la Cruz (30°16'19.50"S; 57°19'12.72"W), Cuareim River, Artigas Department, Uruguay, col.: W.S. Serra, M. Loureiro, F. Teixeira de Mello, S. Villars, D. Olsson, N. Zaldúa & F. Stábile, 26-27/IX/2015. MHNM 3994, 2 ex., 24,4-28,6 mm SL, Paso de León (30º08'12,11''S; 57º06'14,73''W), Cuareim River, Artigas Department, Uruguay, col.: W.S. Serra, M. Zarucki, M. Loureiro & D. Arrieta, 22/III/2014. MHNM 4051, 2 ex., 13,3-19,9 mm SL, Arroyo Lemos (30°19'37,53"S; 56°34'31,08"W), Artigas Department, Uruguay, col.: M. Loureiro, F. Teixeira de Mello, I. González-Bergonzoni & F. Quintans, III/2007. MHNM 4067, 1 ex., 25,8 mm SL, pond near Uruguay River (31°04'19,98"S; 57°51'32,83"W), Villa Constitución, Salto Department, Uruguay, col.: W.S. Serra, 22/X/2016. ZVC-P 2674, 22 ex., 20,2-31,3 mm SL, Arrocera CONTI in front of Isla del Zapallo (30°30'00,03"S; 57°51'24,97"W), Uruguay River, Artigas Department, Uruguay, col.: C. Ríos & J. González, 01/VII/1979. ZVC-P 5224, 7 ex., 25,0- 30,8 mm SL, Arrocera CONTI in front of Isla del Zapallo (30°30'00,03"S; 57°51'24,97"W), Uruguay River, Artigas Department, Uruguay, col.: C. Ríos & J. González, 01/VII/1979. ZVC-P 7971, 1 ex., 31. 2 mm SL, Aº Higueritas (33°52'50.92"S; 58°24'36.96"W), Nueva Palmira, Colonia Department, Uruguay, col.: R. Vaz-Ferreira, B. Sierra de Soriano & J. Soriano, 22/IX/1962. ZVC-P 8136, 1 ex., 27,5 mm SL (fixed in 95% Ethanol), Laguna Redonda, Rincón de Franquia (30°13'09,38"S; 57°37'20,32"W), Bella Unión, Artigas Department, Uruguay, col.: I. González-Bergonzoni & A. Duarte, 01/XI/2007. ZVC-P 8201, 20 ex., 14,7-25,8 mm SL, Estancia El Espinillar – ANCAP (30°57'50,61"S; 57°49'41,85"W), Salto Department, Uruguay, col.: R. Vaz-Ferreira & F. Achaval, 25/I/1980. ZVC-P 10867, 2 ex., 22,1-25,0 mm SL, Arroyo Yucutujá (30°20'49,42"S; 57°19'43,00"W), Artigas Department, Uruguay, II/2006. ZVC-P 12558, 2 ex., 26,9- 29,5 mm SL, Paso de León (30°08'12,11"S; 57°06'14,03"W), Artigas Department, Uruguay, col: A. Duarte, W.S. Serra & M. Loureiro, 4/XII/2012. ZVC-P 14190, 2 ex., 22,4-25,2 mm SL. (fixed in 95% Ethanol), Laguna Redonda (30°13'09,38"S; 57°37'20,32"W), Bella Unión, Artigas Department, Uruguay, col.: M. Loureiro, J. Bessonart, M. Zarucki & S. Paullier, 17/VIII/2017. ZVC-P 14193, 8 ex., 17,6-30,5 mm SL., Laguna Redonda (30°13'09,38"S; 57°37'20,32"W), Bella Unión, Artigas Department, Uruguay, col.: M. Loureiro, J. Bessonart, M. Zarucki & S. Paullier, 17/VIII/2017. ZVC-P 14195, 1 ex., 23,9 mm SL, Franquia (30°12'34,26"S; 57°37'29,76"W), Bella Unión, Artigas Department, Uruguay, col.: M. Loureiro, J. Bessonart, M. Zarucki & S. Paullier, 18/VIII/2017. ZVC-P 14198, 1 ex., 24,0 mm SL, Arroyo del Cortado (30°08'56,34"S; 57°05'55,34"W), Artigas Department, Uruguay, col.: A. Duarte, W.S. Serra & M. Loureiro, 5/XII/2012. ZVC-P 14199, 5 ex., 18,0- 23,6 mm SL, Cañada del Sauzal de la Divisa (30°19'54,09"S; 57°25'30,08"W), Artigas Department, Uruguay, col.: M. Loureiro, F. Teixeira de Mello, I. González-Bergonzoni & F. Quintans, III/2007.

This species differs from other congeners from the La Plata River basin by the following combination of characters: premaxillary teeth with 7-9 cusps, dorsal fin hyaline, incomplete lateral line, abdominal black spot absent and procurrent rays of the ventral profile of the caudal peduncle not anteriorly curved (Almirón et al., 2015; Jerep & Malabarba, 2014; Malabarba & Jerep, 2014; Mantinian, 2011; Miquelarena et al., 2008).

Uruguayan specimens present all the mentioned characters and come from Artigas, Salto and Colonia Departments, mainly associated to the Uruguay River and its affluent, the Cuareim River (fig. 3). These specimens were collected in shallow lagoons, canals and wetlands. The material (one specimen) from Colonia was collected in a stream that drains into the Río de la Plata just in front of the Paraná River. We suggest that the presence of S. calliurus in the southwestern Uruguay is related to the latter river, probably not forming established populations in Colonia. Previously reported distribution of S. calliurus extends through La Plata River basin and Patos Lagoon System, in Argentina, Bolivia, Brazil, Paraguay and Uruguay (Miquelarena et al., 2008; Mantinian, 2011; Malabarba, 2003; Sarmiento et al., 2014).

Reichert (2002) offers a drawing and a brief description of the coloration of “ Serrapinnus piaba ”, both quite non diagnostic as presented. The author does not specify if the drawing effectively belongs to a specimen collected in Uruguay or not. We formally attribute this record to S. calliurus due to the lack of the abdominal spot in the illustration by Reichert. Serrapinnus piaba inhabits the São Francisco River basin and northeastern coastal Atlantic drainages in Brazil (Malabarba & Jerep, 2014) and previously to the revision of Malabarba (1998) it was widely recorded in South America through La Plata, Amazon and San Francisco river basins (Géry, 1977).

Carrera (1976) listed Serrapinnus piaba (under Cheirodon) for Uruguay, without providing a list of the examined material. In the Museo Nacional de Historia Natural (Montevideo), we located material from Uruguay that may correspond with the specimens examined by Carrera (1976). Four lots (of six listed in the catalog) were found; one actually belongs to Serrapinnus calliurus (MHNM 984) and other two (MHNM 1173 and MHNM 1123) are Cheirodon ibicuhiensis Eigenmann, 1915. All were identified by E. Messner as " Cheirodon piaba ". Messner, along with Carrera, worked in the MHNM. The fourth lot in the catalog (MHNM 1207) should be splitted, as it contains specimens with five different tattooed numbers of the Messner’s personal catalog: M768 and M979 are specimens of Cheirodon interruptus, M990 and M861 are C. ibicuhiensis, and M 796 specimens of S. calliurus. We reassigned the number MHNM 1207 to the latter, and the other four lots were provided with new numbers from the catalog (M768 to MHNM 4066, M861 to MHNM 4064, M979 to MHNM 4065, and M990 to MHNM 4063). Nión et al. (2002) also listed Serrapinnus piaba for Uruguay without providing a list of examined material, apparently based on Carrera (1976), and therefore considering C. ibicuhiensis and C. interruptus under the concept.

Malabarba (2003) listed Serrapinnus calliurus for Uruguay, again without providing examined material or mentions of previous citations, probably based on Nión et al. (2002). Miquelarena et al. (2008) listed S. calliurus probably based on Malabarba (2003). Litz & Koerber (2014) listed S. calliurus based on Nión et al. (2002) taking in consideration Malabarba (2003) who restricted S. piaba to the São Francisco river basin (Brazil). Loureiro et al. (2013) listed Serrapinnus sp. from Uruguay, based on most of the material here reported (although not detailed or identified at species level at that moment) and therefore including both S. calliurus and S. kriegi. Finally, the mention of Serrapinnus piaba in Nión et al. (2016) probably was due to the omission of the data provided by Malabarba (2003), who also mentioned for the first time C. ibicuhiensis for Uruguay, and Litz & Koerber (2014). In the absence of any mention of examined material we assume that the specimens cited as S. piaba by them are actually S. calliurus.