Astyanax laticeps ( Teleostei : Characiformes : Characidae ) from rivers and streams of Uruguay

Several species of Astyanax – currently diagnosed as a combination of several broadly distributed features among Characidae – are known in the rivers of the República Oriental del Uruguay. MESSNER (1962) recorded several species and subspecies of Astyanax in rivers and streams of that country. Since that moment, no other articles are known concerning the genus Astyanax although several new species have been described in close regions (AZPELICUETA & GARCÍA, 2000; BERTACO & MALABARBA, 2001; CASCIOTTA et al., 2003). The examination of collections of Facultad de Ciencias (Universidad de la República, Uruguay) and Museo Nacional de Historia Natural y Antropología and those material studied by MESSNER (1962) allow us to record Astyanax laticeps (COPE, 1894) in streams Astyanax laticeps (Teleostei: Characiformes: Characidae) from rivers and streams of Uruguay


Introduction
Several species of Astyanax -currently diagnosed as a combination of several broadly distributed features among Characidae -are known in the rivers of the República Oriental del Uruguay.MESSNER (1962) recorded several species and subspecies of Astyanax in rivers and streams of that country.Since that mo-ment, no other articles are known concerning the genus Astyanax although several new species have been described in close regions (AZPELICUETA & GARCÍA, 2000;BERTACO & MALABARBA, 2001;CASCIOTTA et al., 2003).The examination of collections of Facultad de Ciencias (Universidad de la República, Uruguay) and Museo Nacional de Historia Natural y Antropología and those material studied by MESSNER (1962) allow us to record Astyanax laticeps (COPE, 1894) in streams

Materials and Methods
Measurements are straight distances taken with calliper to nearest 0.1 mm.dorsal-fi n rays in most specimens.Tip of pectoral fi n far from pelvic-fi n origin even in small specimen.Tip of pelvic fi n reaching anal-fi n origin in small although far from it in adults.
Scales cycloid, without circuli on posterior fi eld.Lateral line with 36 (4 ex.), 37 (8 ex.), 38 (5 ex.) or 39 (1) perforated scales.Scales between dorsal-fi n origin and lateral line 6-7; scales between lateral line and pelvic fi n origin 5-6.Scales around caudal peduncle 17 (2) or 18 (16).Scales between tip of supraoccipital spine and base of dorsal fi n 12-14, usually forming an irregular row.Short row of scales forming a sheath covering base of unbranched and fi rst 10 branched  anal-fi n rays.Few scales covering only the base of caudal-fi n lobes.
Colour of alcohol preserved specimens.Flanks of body darker dorsally; head dark; chromatophores located on posterior margin of scales forming a reticu-lar pattern especially notable on upper half of fl anks, although present on anteroventral region of body in most specimens.In some specimens, there are concentrations of chromatophores between scales forming lines that resembles those of A. lineatus.One black humeral spot horizontally oval or rounded, surrounded by a light area.A vertically elongated projection of this humeral spot in few specimens.Origin of black wide lateral stripe at different levels but usually close to humeral spot, lateral stripe ending at tip of caudalfi n rays with a broader area on caudal peduncle.Tip of dorsal fi n dusky; margin of caudal fi n darker; paired fi ns hyaline.A fresh specimen from arroyo Alférez is shown in fi gure 3.
Distribution and biological notes.All localities where A. laticeps were found are over 50 meters above sea level, in tributaries of the main rivers of Laguna Merin basin, and tributaries of Laguna Castillos and Laguna de Rocha basins.Furthermore, recent collections in the protected area of Quebrada de los Cuervos (tributaries of río Olimar, Dep.Treinta y Tres, Fig. 4A) include juvenil and adult specimens from small upstream isolated ponds and pools, temporary disconnected from main creeks and streams.The juveniles were found in ponds located in the head waters of streams (Figure 4B) while adults were found in those places and also in isolated pools of high slope streams (descending 60 meters in less than 500 meters) (Figure 4C).EIGENMANN (1921EIGENMANN ( , 1927) ) included several subspecies of Astyanax scabripinnis in his large paper about Characidae, being one of them A. s. laticeps.MALA-BARBA (1989) restricted the geographical distribution of A. s. laticeps to the Laguna dos Patos system, in Brazil.BERTACO & MALABARBA (2001) demonstrated that some of the subspecies of the A. scabripinnis complex are valid species.LIMA et al. (2003) mentioned A. laticeps also considering its distribution restricted to Rio Grande do Sul, in the laguna dos Patos system although with a question mark.MESSNER (1962) studied some samples included in this paper, identifying them as A. scabripinnis (ZVC P 1427), A. s. paranae (ZVC P 1428, ZVC P 1420), and A. s. laticeps (ZVC P 1765).All those specimens correspond to A. laticeps.Astyanax laticeps is distinguished from other species of Astyanax by low body, scarcely deeper at dorsal-fi n origin (28.2-37.3% of SL at dorsal-fi n origin, 28.0-33.8taken at the level of a vertical through middle pectoral fi n); blunt snout; 1-4 maxillary teeth; 18-24 branched anal-fi n rays; 36-39 perforated scales in lateral line; 6-7/5-6 transverse scales; short caudal peduncle (12.6-13.7 % of SL); dorsal-fi n origin nearer snout than caudal-fi n rays origin; a horizontally oval or rounded humeral spot, surrounded by a light area; bony hooks of males restricted to 1-5 branched pelvic rays and 7-11 anteriormost anal-fi ns rays of mature males.

Discussion
Astyanax laticeps is found in different rivers and streams of the laguna Merín, laguna Castillos, and la-guna de Rocha basin, in Uruguay (Fig. 4).Although, the later lagoons basins currently outfl ow to the Atlantic Ocean, the distribution of this species support a past connection of these systems to those of Laguna Merín.This scenario may correspond to the sea level fl uctuations reported for this region (SPRECHMANN, 1978;MONTAÑA & BOSSI, 1995;GARCÍA-RODRIGUEZ, 2003) or basin capture events that connected these water bodies.Morevover, at least other seven endemic species of the laguna dos Patos-Merin system are present in Laguna Castillos tributaries (Mimagoniates inequalis, Heptapterus sympterigyum, Hyphessobrycon boulengeri, Aus trolebias cheradophilus, A. viarius, A. luteofl amulatus, and Cynopoecilus melanotaenia) and other one in Laguna de Rocha tributaries (Austrolebias luteofl amulatus) (LOUREIRO & GARCÍA, 2006).Comparisons with specimens from Brazil (see material and Fig. 2) reveal same characters and measurements.
Vertebrate Zoology ■ 59 (1) 2009 Dorsal-fi n origin located nearer snout tip than base of caudal-fi n rays.Pelvic-fi n origin located anterior to vertical through dorsal-fi n origin.Anal-fi n origin located notably behind vertical line through base of last
Tab. 1. Measurements of 18 specimens of Astyanax laticeps from streams of Uruguay.Body depth 1 indicates body depth at dorsal-fi n origin; body depth 2 indicates depth at vertical through middle pectoral-fi n.