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Ichthyological Contributions of PecesCriollos 22: 1-3 (2011) 1

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Presence of Australoheros facetus (Teleostei: Cichlidae) in the southern Pampean area. Considerations about the ichthyofaunal settlement and distribution in the Southern boundary of the Brazilian Subregion. María Cecilia Bruno1,3, Marta Lizarralde1, Adriana Almirón2 & Jorge Casciotta2,3

1 CREG, Centro Regional de Estudios Genómicos, UNLP. Av. Calchaquí Km 23,5, Florencio Varela, Buenos Aires, Argentina. Email: [email protected] 2 División Zoología Vertebrados, Museo de La Plata, UNLP, Paseo del Bosque, 1900 La Plata, Argentina 3 CIC, Comisión de Investigaciones Científicas de la provincia de Buenos Aires Abstract The discovery of Australoheros facetus in two streams of the Atlantic coastal drainage in Southern Buenos Aires province extends the distribution range for this species some 200 km to the south. Since there is no connection between the streams of the Atlantic slope and the La Plata basin this raises a question about the current distribution of the species in this area. Historical, geological and climatic factors could be responsible for the current distribution of fishes in the southern Pampean area. Resumen El hallazgo de Australoheros facetus en dos ambientes de la cuenca de pendiente Atlántica en la provincia de Buenos Aires extiende el rango de distribución para esta especie en alrededor de 200 Km al sur. Debido a que no existe conexión entre los arroyos de pendiente Atlántica con la Cuenca del Plata, se plantean interrogantes acerca de la distribución actual de las especies en dicha área. Factores climáticos, geológicos e históricos podrían ser responsables de la distribución actual de los peces en el área Pampeana austral. Introduction The rivers and streams of the Atlantic coastal drainage in the Argentinean Pampean area represent the southern boundary of the Brazilian Subregion (Casciotta et al., 1999). Most of these streams originate in elevated areas of Ventana and Tandil systems and flow into the Atlantic ocean or disappear from the surface before reaching the coast (Kruse et al., 1996). These streams flow parallel and are not connected to each others, nor to the ones flowing northward from these mountain systems. The cichlid fishes are restricted to tropical and subtropical freshwaters, however some species have a certain tolerance to salinity (Gomez & Gonzalez Naya, 2007; Murray, 2001). The recently established genus Australoheros Říčan & Kullander, 2006 has a wide distribution including the Atlantic coastal drainages of Brazil, Uruguay, and Argentina, and La Plata basin (Casciotta et al., 1995, Casciotta et al., 2006; Říčan & Kullander, 2003, 2008).

Fig. 1. Australoheros facetus from Arroyo Claromecó upon capture

Fig. 2. Arroyo Claromecó, one of the new localities where A. facetus was collected

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The genus Australoheros includes 20 valid species (Rican et al., submitted); among these A. facetus (Jenyns, 1842) has a widespread distribution in Argentina, inhabiting the basins of ríos Paraná, Uruguay and Río de la Plata, and Atlantic coastal drainages (Casciotta, 1998). Up to now, the southernmost record of A. facetus was from the río Quequén Grande in Buenos Aires province (Ringuelet, 1975). The purpose of this paper is to register the presence of A. facetus (Fig. 1) in the arroyo Claromecó (Fig. 2) and río Sauce Grande, in the Pampean area, extending the southern boundary for this species, and to consider biogeographic implications of this presence. Material examined Australoheros facetus. MACN-ict 9584, 1 ex., 30.5 mm SL, Argentina, Buenos Aires province, arroyo Claromecó, (38° 42’ 13,7’’ S – 60° 10’ 10’’W) (Figs: 1, 3). MACN-ict 9583, 3 ex., 57.7-68.9 mm SL, Argentina, Buenos Aires province, río Sauce Grande (38° 45’ 44,6’’ S – 61° 42’ 42’’ W).

Fig. 3. Southernmost geographical distribution of A. facetus. Localities of collection in the Atlantic coastal drainage: 1: río Quequén Grande, 2: arroyo Claromecó, 3: río Sauce Grande. Discussion The Brazilian subregion includes the central, Eastern and Northern parts of the Argentinian territory. At present it is considered that the Southern boundary for this region is the río Negro (Almirón et al., 1997, Casciotta et al., 1999). The finding of Australoheros facetus in the arroyo Claromecó and río Sauce Grande, Atlantic coastal drainages, extends its distribution more than 200 km South-West (Fig. 3). This species as was noted above is also present in several drainages of La Plata basin. Since there is no connection between the streams of Atlantic drainages and La Plata basin, it raises a question about the current distribution of the species in this area. Cione & Barla (1997) and Casciotta et al. (1999) proposed five hypotheses to explain the presence and distribution of fishes in the southern Pampean area: 1. The species were present in the southern Pampean area before the last glacial periods and

withstood the unfavorable climate. This could be feasable as A. facetus actually has a widespread distribution in the area, occupying many of the Atlantic drainage streams.

2. Fishes entered in the area by drainages presently summerged on the shelf. About twenty cold periods have occurred during the present Glacial Age. During these periods, sea-level dropped about 120 m. At the latitude of the Ventana, the shelf is very wide. In the presently flooded area, many drainages surely existed during glacial periods. These drainages could have been connected with northern rivers. This hypothesis could be verified by molecular studies of demographic history and phylogeography of the species that inhabit the area.

3. The fishes could have entered in the área due to flooding that crossed Tandilia. Floodings have been common in the pampean area, but they have not historically documented crossing Tandilia, therefore there are no faunal interchanges today with northern basins.

4. Marine dispersal. This could apply to amphibiotic species such as Mugil liza. Cichlids are restricted to freshwater and brackish marine environments. Murray (2001) considered a possible oceanic dispersal to explain current distribution of cichlids and Azpelicueta et al. (1998) recordered A. facetus living in high values of salinity (13 ‰). However, so far there is no record of A. facetus from a marine environment.

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5. Human introduction. This could be applied to the finding of this species because it has ornamental importance. The distribution of A. facetus in the area including the río Quequén Grande, arroyo Claromecó and río Sauce Grande, suggesting a continuum in the range. In addition, there is no evidence of anthropochory for this species in the Atlantic coastal drainages.

The expansion in the range of distribution of A. facetus can be attributed to several causes, as mentioned above. In order to define a more specific pattern about the actual distribution and possible means of settlement of this species and others occuring in the area (see Casciotta et al., 1999), we are conducting studies on phylogeography and historical demography, which consider the paleoclimatic effects that might affect persistence and distribution of the icthyofauna in the southern Pampean area. Finally the presence of A. facetus in the Atlantic coastal drainages represents the southernmost limits for Cichlasomatinae. Acknowledgements The authors thank to Fernando Mapelli for his collaboration during collecting trips and different stages of this paper. References Almirón, A., M. Azpelicueta, J. Casciotta & A. López Cazorla (1997): Ichthyogeographic boundary between the Brazilian and Austral subregions in South America, Argentina. Biogeographica 73: 23-30 Azpelicueta, M., D.E. Figueroa, J.M. Díaz de Astarloa & M.B. Cousseau (1998): Freshwater fishes in a world reserve biosphere: Mar Chiquita coastal lagoon (Buenos Aires, Argentina). Biogeographica 74: 85-90 Casciotta, J.R. (1998): Cichlid-fishes from la Plata basin in Argentina: Laetacara dorsigera (Heckel), Bujurquina vittata (Heckel), and ‘Cichlasoma’ facetum (Jenyns) (Perciformes: Labroidei). Neotropica 44 (111-112): 23-39 Casciotta, J., A. Almirón, A. Cione & M. Azpelicueta (1999). Brazilian freshwater fish assemblages from southern Pampean area, Argentina. Biogeographica 75: 67-78 Casciotta, J.R., S.E. Gómez & N.I. Toresani (1995): ‘Cichlasoma’ tembe, a new cichlid species from the río Paraná basin, Agentina (Osteichthyes: Labroidei). Ichthyological Explorations of Freshwaters 6: 193-200 Casciotta, J., A. Almirón & S. Gómez (2006): A new species of Australoheros (Teleostei: Perciformes: Cichlidae) from the río Iguazú basin, Argentina. Zoologische Abhandlungen 55: 77-83 Cione, A. & M. Barla (1997): A new locality for the synbranchid eel Synbranchus marmoratus (Teleostei: Percomorpha) in southern Buenos Aires Province, Argentina. Neotropica 43: 113-115 Gómez, S.E. & M.J. Gonzalez Naya (2007): Resistencia a la salinidad en dos especies de peces neotropicales de la familia Cichlidae (Pisces, Perciformes). Memoria de la Fundación La Salle de Ciencias Naturales 2007 (“2006”) 166: 47-57 Kruse, E., M. Deluchi, L. Varela & P. Laurencena (1996): Escenarios geoambientales en la llanura interserrana de la Provincia de Buenos Aires. Actas XIII Congr. Geol. Arg. y III Congr. Explor. Hidrocarburus. Buenos Aires 2: 117-130 Murray, A.M. (2001): The fossil record and biogeography of the Cichlidae (Actinopterygii: Labroidei). Biological Journal of the Linnean Society 74: 517-532 Říčan, O. & S.O. Kullander (2003): 'Cichlasoma' scitulum: a new species of cichlid fish from the Río de La Plata Region in Argentina, Brazil, and Uruguay. Copeia 2003: 794-802 Říčan, O. & S.O. Kullander (2008): The Australoheros (Teleostei: Cichlidae) species of the Uruguay and Paraná River drainages. Zootaxa 1724: 1-51 Říčan, O., L. Piálek, A. Almirón & J. Casciotta (submited): Two new species of Australoheros (teleostei:

Cichlidae), with notes on diversity of the genus and biogeography of the Río de la Plata basin. Zootaxa Ringuelet, R.A. (1975): Zoogeografía y ecología de los peces de aguas continentales de la Argentina y consideraciones sobre las áreas ictiológicas de América del Sur. Ecosur 2 (3): 1-122 recommended form for reference: Bruno, M.C., M. Lizarralde, A. Almirón & J. Casciotta (2011): Presence of Australoheros facetus (Teleostei: Cichlidae) in the southern Pampean area. Considerations about the ichthyofaunal settlement and distribution in the southern boundary of the Brazilian Subregion. Ichthyological Contributions of PecesCriollos 22: 1-3 available as pdf-file at www.pecescriollos.de since 16.Jun.2011