Sunday, January 14, 2018

[Ichthyology • 2017] Gymnogeophagus taroba • A New Species (Teleostei: Cichlidae) from the río Iguazú Basin, Misiones, Argentina

Gymnogeophagus taroba
 Casciotta, Almirón, Piálek & Říčan, 2017

HISTORIA NATURAL. Tercera Serie. 7(2)


 The Gymnogeophagus setequedas group is based on our results composed of three endemic species of which one, Gymnogeophagus taroba sp. n., is described as a new species. The three species are diagnosable from each other and from other species of Gymnogeophagus by stable differences in several morphological characters among which the best are found in coloration patterns. Body and head shapes and meristic characters show lesser differentiation but several are also clearly diagnostic in the G. setequedas group. The G. setequedas group is strongly structured allopatrically. The prime candidates for this fragmentation and speciation are the origins of the waterfalls on the individual tributaries. The largest of the waterfalls, the famous Cataratas del Iguazú, with a height of 72 m, separate G. taroba sp. n. from its closest relatives G. che and G. setequedas. The original 28 m high Urugua-í falls separate G. che from G. setequedas. Gymnogeophagus setequedas is separated from G. che and G. taroba by large rapids (about 65m in total elevation above the río Paraná) and a former fall on the Acaray river and by the 45 m high Monday falls located a few km from the mouth of the Monday into the río Paraná just opposite the mouth of the Iguazú.

 Key words. Cichlid fishes, endemism, morphology, La Plata River basin, Paraná river basin

Figure 3- Gymnogeophagus taroba, coloration of live specimens immediatelly after capture.
 (A-B) IBIGEO-I 449, paratype specimens, 87.8 mm, 79.8 mm. (C-D) MLP uncat., Říčan et al., February 2014, data as holotype. 

Family Cichlidae Bonaparte, 1835
Genus Gymnogeophagus Miranda Ribeiro, 1918

Gymnogeophagus taroba, new species (Figures 1-7; Table 1)

Gymnogeophagus aff. setequedas Casciotta et al., 2016
(photo of live holotype, first mention of the species)

Diagnosis. Gymnogeophagus taroba is distinguished from all species of Gymnogeophagus in the G. gymnogenys group by the possession of 23 to 25 E1 scales and the absence of a well developed adipose hump in adult males. Gymnogeophagus taroba is most easily distinguished from all species in the G. rhabdotus group (G. terrapurpura, G. rhabdotus, G. meridionalis, G. setequedas and G. che) by the pigmentation of the dorsal fin. ....


Etymology. The specific epithet taroba refers to Tarobá, a warrior, and refers to a legend of the Kaingang people; a noun in apposition. The Kaingang were the original first inhabitants of the present province of Misiones in Argentina and the southern Brazilian states of Paraná, Santa Catarina and Rio Grande do Sul and also the southeastern state of São Paulo. Their language and culture is quite distinct from the neighboring Guaraní. The Kaingang language is classified as a member of the Gê language family. The legend tells that at the beginning of time, the río Iguazú was inhabited by a huge and monstrous serpent called Mboi, a guardian god. The Kaingang sacrificed a beautiful young maiden every year to Mboi. When Tarobá meets Naipí, chosen for the sacrifice, he rebells against the elders of the tribe who refuse to release her. Tarobá and Naipí try to escape in a canoe by the river. Mboi becomes furious and brakes the course of the river forming the Iguazú falls, catching the lovers. Naipí is transformed into one of the rocks of the falls, perpetually punished by the turbulent waters, and Tarobá is turned into a palm tree on the bank of the waterfall. Mboi lives submerged in the Garganta del Diablo, from where he watches over the lovers, preventing them from joining again. However, on sunny days and as a bridge of love, the rainbow overcomes the power of Mboi by rejoining Naipí and Tarobá.

Jorge Casciotta, Adriana Almirón, Lubomir Piálek and Oldřich Říčan. 2017. Gymnogeophagus taroba (Teleostei: Cichlidae), A New Species from the río Iguazú Basin, Misiones, Argentina.  HISTORIA NATURAL. Tercera Serie. 7(2); 5-22.

Resumen. En base a nuestros resultados, el grupo Gymnogeophagus setequedas esta compuesto por tres especies endémicas, de las cuales, G. taroba sp. n., se describe como una nueva especie. Las tres especies son diagnosticables entre sí y de otras especies de Gymnogeophagus por diferencias estables en varios caracteres morfológicos, entre los cuales los mejores son los patrones de coloración. La forma del cuerpo, la cabeza y los caracteres merísticos muestran una menor diferenciación, pero algunos también son claramente diagnósticos en el grupo G. setequedas. El grupo G. setequedas está fuertemente estructurado alopátricamente. La causa principal para esta fragmentación y especiación es la formación de cascadas en los afluentes. La más grande de las cascadas, la famosa Catarata del Iguazú, con una altura de 72 m, separa G. taroba sp. n. de sus parientes más cercanos G. che y G. setequedas. El salto original del Urugua–í de 28 m de altura, separa G. che de G. setequedas. Gymnogeophagus setequedas está separada de G. che y G. taroba por grandes rápidos (unos 65 m de elevación total sobre el río Paraná) y un primer salto en el río Acaray y por otro salto de 45 m de altura en el río Monday localizado a unos pocos kilómetros de la desembocadura del Monday en el río Paraná justo enfrente de la desembocadura del Iguazú. 
Palabras clave. Cíclidos, endemismo, morfología, Cuenca del Plata, Cuenca del río Paraná