Rediscovery of <i>Crenicichla yaha</i> (Teleostei: Cichlidae)

Abstract

<i>Crenicichla yaha</i> was described from the Urugua-í river (arroyo Urugua-í; and erroneously on one specimen from the Rio Iguazú) in Misiones, Argentina. The species was only known from nine specimens collected in 1986 during an environmental impact study prior to the construction of the Urugua-í hydroelectric dam in 1989. The species has not been collected since and is absent from the artificial lake where ecological conditions have been severely altered and where the diversity and biomass of non-native species are on the increase. We report here the rediscovery of <i>Crenicichla yaha</i> in the Urugua-í basin based on nine specimens collected in December 2016 at two localities outside the influence of the artificial lake. The species is distinct (especially in live coloration) from <i>Crenicichla tesay</i> which was previously treated as conspecific with it or confused with it. <i>Crenicichla yaha</i> is endemic to the Urugua-í river basin, while <i>Crenicichla tesay</i> is endemic to the Iguazú river basin. The original description of <i>Crenicichla yaha</i> was based on long preserved specimens lacking most coloration patterns. We expand the description and diagnosis of the species with the now known coloration patterns based on live specimens including breeding coloration and rediagnose the species by comparisons with the remaining closely related species of the <i>C. mandelburgeri</i> species group which were not known at the time of the original description of <i>C. yaha</i>.