Friday 16 August 2013

A new species of Cichlid Fish from the Río Acaray in Paraguay.

The Cichlids are an extremely successful group of freshwater Perciform Fish (Perches), found in North, Central and South America, as well as the Caribbean, the Middle East, South Asia and, most notably Africa, where the group reaches its highest diversity. There are one of the most diverse Fish, and therefore Vertebrate, families, with over 1600 described species. Over 700 species have been described from Lake Malaŵi alone, which is more species of freshwater fish than have been described from the entire Northern Hemisphere and slightly over 1% of every vertebrate species ever described. hey are popular in the aquarium trade, which has led to them becoming naturalized in many parts of the world where they are not native.

In a paper published in the journal Zootaxa on 23 April 2013, Sven Kullander of the Department of Zoology at the Swedish Museum of Natural History and Carlos de Lucena of the Laboratório de Ictiologia at the Museu de Ciências e Tecnologia at the Pontifícia Universidade do Rio Grande do Sul describe a new species of Cichlid Fish from the Río Acaray drainage basin in Paraguay.

The new species is placed in the genus Crenicichla and named Crenicichla gillmorlisi, in honour of Walter Gill Morlis, a fisheries officer of the Itaipú Binacional Hydroelectric Project in Ciudad del Este, Paraguay. Crenicichla gillmorlisi is a silvery Cichlid Fish with an olive sheen reaching 174 mm in length. It has a specked body and a distinctive bar beneath the eye.

Crenicichla gillmorlisi, male specimen from the Yguazú Reservoir. Walter Gill Morlis in Kullander & de Lucena (2013).

Crenicichla gillmorlisi appears to be restricted to the drainage basin of the Río Acaray, a tributary of the  Río Paraná, where it appears to dwell close to overgrown riverbanks, often with turbid water. The Río Acaray now has two barriers to Fish movement, the Acaray Hydroelectric Power Plant and the Yguazú Reservoir, both of which dam the river. This clearly divides the population of Crenicichla gillmorlisi into smaller sub-populations, though what effect this is having on the long-term viability of the species is unclear.

The known distribution of Crenicichla gillmorlisi; black spots represent sites where the fish has been found. Kullander & de Lucena (2013).

Typical habitat where Crenicichla gillmorlisi has been found. Kullander & de Lucena (2013).

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