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A new species of Propimelodus Lundberg & Parisi, 2002 Siluriformes: Pimelodidae...

A new species of Propimelodus from the middle course of the rio Araguaia is described. Propimelodus araguayae, new species, can be distinguished from its congeners in having a conspicuous black dot on the base of the dorsal-fin rays (vs. a different pattern), large eyes (29.7-34.8% of head length and 62.7-74.7% of snout length vs. 14.5-21.1% and 31-44% in P. caesius and 9.5-19.7% and 17-38% in P. eigenmanni), a...

Two new ornamental loricariid catfishes of Baryancistrus from rio Xingu drainag...

Two new species of the hypostomine genus Baryancistrus are described from the rio Xingu drainage. Baryancistrus xanthellus is distinguished from all other Baryancistrus species by the presence of yellow spots along the entire body and conspicuous yellow marks on distal tip of dorsal and caudal fins. Baryancistrus chrysolomus is distinguished from its congeners by its uniform dark body coloration and presence of...

A new species of Ancistrus Kner, 1854 (Siluriformes: Loricariidae) from rio Mad...

During the Mosaico do Apuí expedition in 2006, a new species of Ancistrus was found in the rio Sucunduri, a large tributary of the rio Madeira basin in south Amazonas State. The new species has a unique color pattern for the genus and is distinguished by the presence of alternate light and dark vertical bars on the trunk. Other Ancistrini genera have species with a similar color pattern, but the new species is ...

A new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from th...

Hypostomus delimai is described from the rio Tocantins, Tocantins State, and from the rio Araguaia, Pará, and Tocantins States, Brazil. The new species is distinguished from all other Hypostomus species, except from H. carinatus, H. hoplonites, and H. watwata, by the presence of five to eight (mode seven) predorsal plates limiting posterior border of the supraoccipital bone (vs. one to three plates). It can be ...

Two New Species of the Armored Catfish Genus Baryancistrus Rapp Py-Daniel, 1989...

Unexpected species diversity in electric eels with a description of the stronge...

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioele...

Hypoxic environments as refuge against predatory fish in the Amazonian floodplains

Several groups of Amazonian fishes exhibit behavioral, morphological and physiological characteristics that allow occupying hypoxic environments, despite the energetic costs of living in such harsh conditions. One of the supposed advantages of occupying hypoxic habitats would be a lower predation pressure resulting from a lower number of piscivorous fishes in those environments. We tested this hypothesis in an ...

Karyotype characterization and ZZ/ZW sex chromosome heteromorphism in two speci...

We present karyotypic characteristics and report on the occurrence of ZZ/ZW sex chromosomes in Ancistrus ranunculus (rio Xingu) and Ancistrus sp. "Piagaçu" (rio Purus), of the Brazilian Amazon. Ancistrus ranunculus has a modal number of 2n=48 chromosomes, a fundamental number (FN) of 82 for both sexes, and the karyotypic formula was 20m+8sm+6st+14a for males and 19m+9sm+6st+14a for females. Ancistrus sp. "Piaga...

Fish fauna of small streams of the Catua-Ipixuna Extractive Reserve, State of A...

Karyotype description of three species of Loricariidae (Siluriformes) and occur...

The neotropical freshwater systems have a high number of catfish species (Siluriformes), and many of those are denominated "cascudos" in Brazil. Cytogenetic data about three "cascudos" species fished in the rio Araguaia are described in the present study. The Pterygoplichthys joselimaianus showed 2n=52, with 28 metacentrics (M) chromosomes, 16 submetacentrics (SM) and 8 subtelocentrics/acrocentrics (ST/A) in bo...