Population structure and natural diet of Astyanax cf. paranae Eigenmann 1914 a typical species of neotropical headwaters streams

This work describes the habits of individuals of the species Astyanax cf. paranaethat inhabitRibeirão do Ferro,a bedside stream. Overall,92 specimens were analyzed (53 females and 39 males),and the size ranged from class 4.7-5.7 cm to class 10.7-11.7 cm. The females consisted in thelarger portion of the samples,except for classes of 4.7-5.7 and 5.7-6.7 cm. The condition factor between males and females (t = 2.1545; p < 0.05) shows distinguished values,with females having higher averages. Fragments of allochthonous insects and plant matter make up the basis of the species' diet. The study showed that the population of A. cf. paranaeis predominantly females and have the highest standard for length and weight,which may favor biological diversity and increased larvae and juveniles,maximizing the chance of individuals reaching adulthood. The species prefers an environment with predominance of rocks and logs,which favors shelters. Its diet comes mostly from the riparian forest,with a high dependence on the allochthonous items, thus, these vegetations are very important for maintaining populations of the species.

Taxonomic revision of the deep channel electric fish genus Sternarchella (Teleostei: Gymnotiformes: Apteronotidae), with descriptions of two new species

This paper provides a taxonomic revision of the Neotropical electric fish genus Sternarchella, with redescriptions of seven valid species and descriptions of two new species. A maximum parsimony analysis of 76 morphological characters from seven ingroup and seven outgroup taxa recovered a non-monophyletic Sternarchella, in which a clade comprising two species with a ventral mouth (S. orinoco + S. sima) is the sister group to a clade comprising seven species that possess a terminal or superior mouth. Nested within this higher-diversity clade is the genus Magosternarchus (recognized herein as a junior synonym of Sternarchella) comprising M. duccis and M. raptor. The Magosternarchus clade forms a polytomy with S. orthos and S. schotti. Sternarchella calhamazon + a new species from the upper Río Madeira (sister species to S. calhamazon), and a new larger-bodied species from the central and upper Río Amazonas also form a clade. Sternarchella orthos is distributed in both the Amazon and Orinoco basins, where it exhibits considerable phenotypic diversity. Sternarchella orthos includes most specimens from the Amazon formerly assigned to the nominal species S. terminalis (recognized herein as a junior synonym of S. schotti).(AU)

Este artigo propõe uma revisão taxonômica do gênero Neotropical de peixe-elétrico Sternarchella, incluindo a redescrição de sete espécies válidas e duas novas espécies. Análise de máxima parcimônia com 76 caracteres morfológicos e amostragem de sete grupos internos e sete grupos externos indica que Sternarchella não constitui grupo monofilético, sendo um clado composto por duas espécies com bocas ventrais (S. orinoco + S. sima) e outro com sete espécies com bocas terminais ou superiores. Dentro deste último clado estão as espécies do gênero Magosternarchus (reconhecido aqui como um sinônimo júnior de Sternarchella): M. duccis e M. raptor. O clado de Magosternarchus forma uma politomia com S. orthos e S. schotti. Sternarchella calhamazon + uma nova espécie do alto rio Madeira (espécie irmã de S. calhamazon) e uma nova espécie de corpo maior do rio Amazonas central e superior também formam um clado. Sternarchella orthos está distribuída nos rios amazônicos e no Orinoco, onde apresenta elevada diversidade fenotípica. Sternarchella orthos inclui a maioria dos espécimes do rio Amazonas anteriormente atribuídos à S. terminalis (considerada neste estudo como sinônimo júnior de S. schotti).(AU)