Cyanocharax alburnus ( Hensel , 1870 ) ( Characiformes : Characidae ) : First distribution record in Argentina

This note reports the presence of Cyanocharax alburnus in the Argentinian Mesopotamia. This represents the southern distributional limit for the species in South America and the first record for Argentina’s fresh water fish fauna. 1 Instituto de Limnología “Dr. Raúl A. Ringuelet” (CONICET CCT La Plata-UNLP). CC 712, 1900. La Plata, BA, Argentina. 2 Museo de La Plata, División Zoología Vertebrados. Paseo del Bosque s/n, 1900. La Plata, BA, Argentina. * Corresponding author. E-mail: lprotogino@gmail.com.ar Lucila C. Protogino 1,2* and Amalia M. Miquelarena 1,2 Cyanocharax alburnus (Hensel, 1870) (Characiformes: Characidae): First distribution record in Argentina The genus Cyanocharax Malabarba and Weitzman, 2003, included in the family Characidae, comprises smallsized species: C. alburnus (Hensel, 1870), C. alegretensis Malabarba and Weitzman, 2003; C. dicropotamicus Malabarba and Weitzman, 2003; C. itaimbe Malabarba and Weitzman, 2003; C. lepiclastus Malabarba, Weitzman and Casciotta, 2003; C. tipiaia Malabarba and Weitzman, 2003 and C. uruguayensis (Messner, 1962) known only for the Atlantic drainage basins in southeastern Brazil, in the states of Rio Grande do Sul and Santa Catarina and in the Uruguay River drainage basin in Brazil, Uruguay and Argentina. These characids are identified by the following diagnostic characters: presence of two unbranched and eight branched rays in the dorsal fin; absence of insemination; absence of caudal and anal glands or specialized organ; presence of one unbranched and six branched rays in the pelvic fin; possession of clearly anterior mouth with unspecialized teeth, and lack of ventrally located mouth with modified maxillary, premaxillary and dentary bones; branched rays in the anal fin ranging from 21 to 35; and incompletely toothed maxilla, with 2 to 8 teeth (Malabarba and Weitzman 2003). In November 2004, we collected 4 specimens of C. alburnus (Figure 1, Table 1) from Villaguay creek in the beach sector at 31°55’00” S, 59°03’00” W, Villaguay Department, part of the Gualeguay River basin in Entre Ríos province, scientific permit LP N°4892/70, (Figure 2). Villaguay creek is a relatively extensive watercourse, with some sectors about 50 m wide and pools over 2 m deep. The banks are vegetated with grasses and other plants, and the bottom consists of mud and clay. Entre Ríos province represents, along with the rest of the Mesopotamic region, one of the areas of highest biodiversity in Argentina (López et al. 2005). The specimens we collected in Villaguay creek were identified as C. alburnus by the possession of two unbranched and eight branched rays in the dorsal fin, one unbranched and six branched rays in the pelvic fin, four unbranched and 20-24 branched rays in the anal fin, total number of scales in lateral-line row 37-38, scale rows between dorsal-fin and lateral line 5, scale rows between lateral line and pelvic-fin origin 3 and unpigmented adipose fin. Malabarba and Weitzman (2003) diagnose C. alburnus by the presence of a complete series of 36 to 39 perforated lateral-line scales, a character that sets it apart from those species with interrupted lateral line (C. alegretensis, C. lepiclastus, C. tipiaia and C. uruguayensis). Additionally, the presence of an unpigmented adipose fin distinguishes it from C. dicropotamus and C. itaimbe. Figure 1. Cyanocharax alburnus, ILPLA 2172, female, 38.1 mm, Villaguay creek, Entre Ríos Province, Argentina. Figure 2. Habitat of Cyanocharax alburnus, Villaguay creek, Entre Ríos Province, Argentina.

The genus Cyanocharax Malabarba and Weitzman, 2003, included in the family Characidae, comprises smallsized species: C. alburnus (Hensel, 1870), C. alegretensis Malabarba and Weitzman, 2003;C. dicropotamicus Malabarba and Weitzman, 2003;C. itaimbe Malabarba and Weitzman, 2003;C. lepiclastus Malabarba, Weitzman and Casciotta, 2003;C. tipiaia Malabarba andWeitzman, 2003 andC. uruguayensis (Messner, 1962) known only for the Atlantic drainage basins in southeastern Brazil, in the states of Rio Grande do Sul and Santa Catarina and in the Uruguay River drainage basin in Brazil, Uruguay and Argentina.These characids are identified by the following diagnostic characters: presence of two unbranched and eight branched rays in the dorsal fin; absence of insemination; absence of caudal and anal glands or specialized organ; presence of one unbranched and six branched rays in the pelvic fin; possession of clearly anterior mouth with unspecialized teeth, and lack of ventrally located mouth with modified maxillary, premaxillary and dentary bones; branched rays in the anal fin ranging from 21 to 35; and incompletely toothed maxilla, with 2 to 8 teeth (Malabarba and Weitzman 2003).
In November 2004, we collected 4 specimens of C. alburnus (Figure 1, Table 1) from Villaguay creek in the beach sector at 31°55'00" S, 59°03'00" W, Villaguay Department, part of the Gualeguay River basin in Entre Ríos province, scientific permit LP N°4892/70, (Figure 2).According to Malabarba and Weitzman (2003), Cyanocharax species have pelvic-and anal-fin hooks, suggesting they belong to a clade of South American characiforms with fin hooks.We also observed the presence of bony hooks on the dorsal fin.
These records represent the southernmost limit for this species (Figure 3); according to the biogeographical proposal of López et al. (2008), they are located within the Great Rivers Province.
The examined specimens are deposited at Instituto de Limnología "Dr.Raúl A. Ringuelet" (ILPLA) and Museo de La Plata (MLP).We also examined specimens from the collection of the Museu de Ciências e Tecnología PUCRS, Brazil.
Identifications were made using Malabarba and Weitzman (2003).Measurements to the nearest 0.01 mm were made using a digital caliper following Fink and Weitzman (1974).Osteological observations were made on one specimen cleared and stained (c &s) for bone and cartilage following the protocol by Taylor and Van Dyke (1985).Cyanocharax alburnus: Argentina: ILPLA 2172, 3 (1c&s), 35.7-38,33 (37.4) mm SL, Entre Ríos Province, Department Villaguay, Gualeguay River basin, Villaguay creek on the beach area of Villaguay creek, 31°55'00" S, 59°03'00" W, Col. A. Miquelarena, H. López, R. Menni and L. Protogino, 06/11/04; MLP 10177, 39.9 mm SL, the same data as above and Brazil: MCP 7054, 10, 47.0-58.5 (54.2) mm SL, América do Sul, Rio Villaguay creek is a relatively extensive watercourse, with some sectors about 50 m wide and pools over 2 m deep.The banks are vegetated with grasses and other plants, and the bottom consists of mud and clay.Entre Ríos province represents, along with the rest of the Mesopotamic region, one of the areas of highest biodiversity in Argentina (López et al. 2005).The specimens we collected in Villaguay creek were identified as C. alburnus by the possession of two unbranched and eight branched rays in the dorsal fin, one unbranched and six branched rays in the pelvic fin, four unbranched and 20-24 branched rays in the anal fin, total number of scales in lateral-line row 37-38, scale rows between dorsal-fin and lateral line 5, scale rows between lateral line and pelvic-fin origin 3 and unpigmented adipose fin.Malabarba and Weitzman (2003) diagnose C. alburnus by the presence of a complete series of 36 to 39 perforated lateral-line scales, a character that sets it apart from those species with interrupted lateral line (C.alegretensis, C. lepiclastus, C. tipiaia and C. uruguayensis).Additionally, the presence of an unpigmented adipose fin distinguishes it from C. dicropotamus and C. itaimbe.

Table 1 .
Morphometric and meristic data of Cyanocharax alburnus from Argentina.