A new species of the neotropical catfish genus Trichomycterus (Siluriformes : Trichomycteridae) representing a new body shape for the family

Trichomycterus crassicaudatus is described as a new species from the Rio Iguacu basin in southern Brazil. The new species has an exceptionally deep posterior region of the body (caudal peduncle depth 22.8-25.4% SL), resulting in an overall shape which distinguishes it at once from all other members of the Trichomycteridae. The caudal fin of the species is broad-based and forked, a shape also distinguishing it from all other species in the family. A number of autapomorphic modifications of T. crassicaudatus are associated with the deepening of the caudal region, including an elongation of the hemal and neural spines of the vertebrae at the middle of the caudal peduncle. Phylogenetic relationships of the new species are yet unresolved, but it shares a similar color pattern and a thickening of caudal-fin procurrent rays with T. stawiarski, a poorly-known species also from the Rio Iguacu basin. Coloration and body shape also include similarities with T. lewi from Venezuela.

New Species of the Thorny Catfish Genus Leptodoras (Siluriformes: Doradidae) from Rio Fresco, Xingu Basin, Brazil

A new species of the thorny catfish genus Leptodoras (family Doradidae) is described. The new species shares three characters with its congeners, the modified oral hood with distinct upper labial extensions, the first gill arch with enlarged accessory lamellae extending well onto medial face of gill filaments, and the pelvic fin inserted in anterior half of body. The new species is distinguished from congeners by having a large dark submarginal blotch on distal half of dorsal-fin spine and anteriormost dorsal-fin branched rays, lower labial extension of modified oral hood extending more posteriorly than upper labial extension, relatively few midlateral scutes, gas bladder moderately sized (not reduced), paired bony capsules on anteriormost vertebrae reduced to paired cup-like laminar ossifications separated by a triangular septum, pair of small, swelling-like diverticula on each side of the anterior chamber of gas bladder, a well-developed anterior nuchal plate, and nuchal foramina present. The new species was discovered from a single specimen collected in the rio Fresco, a tributary of the rio Xingu, and is described based on this and on additional material recently collected in the same area. A discussion of its placement within Leptodoras is also presented.

Taxonomic Status and Redescription of the Gillbacker Sea Catfish (Siluriformes: Ariidae: Sciades parkeri)

The Gillbacker Sea Catfish is a valid species of ariid catfish from the northeastern coast of South America. There are many synonyms In the literature for the Gillbacker Sea Catfish and even recent classifications have used different scientific names. Examination of a wide range of sizes of Individuals from different localities and examination of types and original species descriptions of Silurus parkeri, Bagrus flavescens, B. emphysetus, Arius physacanthus, A. bonneti, A. clavispinosus, and A. despaxi has lead us to the conclusion that all these names refer to the Gillbacker Sea Catfish and the valid name for the species is Sciades parkeri. The species is distinguished from all other ariid species by the following combination of features: body coloration yellow; swim bladder divided Into three chambers, posterior chamber moderately sized; nuchal plate shield-shaped, usually larger than supraocciptal process; anterior notch of nuchal plate absent; head shield exposed and granulated In orbital and postorbital regions; lateral edge of accessory patches not emarginated or shallowly notched; fleshy furrow connecting posterior nares absent; and mesial gill rakers absent from first two gill arches. Striking intraspecific and/or ontogenetic variation In eye size, maxillary-barbel length, supraoccipital-process size, nuchal-plate size and shape, and dorsal-spine thickness contributed to the numerous synonyms and misidentifications for Sciades parkeri. Bagrus albicans, described from French Guiana, has at times been listed as a synonym of Sciades parkeri. Our examination of the holotype of B. albicans, however, led us to conclude that It is a synonym of Sciades proops.

Systematics of the Jaguar catfish genus Liosomadoras Fowler, 1940 (Auchenipteridae: Siluriformes)

Liosomadoras Fowler, 1940 includes two nominal species: L. oncinus, described from the rio Negro in Brazil, and L. morrowi described from the Peruvian Amazon. Both species are known from only few specimens deposited in fish collections, and information on these fishes is scarce. In order to rectify this situation, diagnoses of the genus and its species and an osteological description off.. oncinus are presented based on recently collected specimens. In addition, the taxonomy of the species of Liosomadoras is reviewed, and L. morrowi is confirmed as distinct from L. oncinus, and also distributed in the Brazilian Amazon. Liosomadoras is hypothesized as a relatively basal genus within Auchenipterinae, sister to all other species of the group, except Asterophysus batrachus and Tocantinsia piresi.

Nuclear abnormalities in erythrocytes and morphometric indexes in the catfish Cathorops spixii (Ariidae) from different sites on the southeastern Brazilian coast

Nuclear abnormalities in erythrocytes (NAE) were taken as biomarkers in the catfish Cathorops spixii (Ariidae) sampled in an estuary little affected by human activity (Cananeia) and in three regions (Santos Channel: SC, Santos Bay: SB and Sao Vicente Channel: SVC) of the Santos-Sao Vicente estuary impacted by various anthropogenic activities. Increases in NAE were observed in fish from SC and SVC sampled in the summer period as compared with specimens from the Cananeia estuary. These results suggest the presence of genotoxic compounds in these regions. However, the absence of significant differences in micronuclei frequency reflects slight mutagenic effects in these individuals. It is possible that the lower NAE frequency in specimens from SB might be associated with the greater remobilization and dilution of chemicals in this region. The low frequency of NAE in C. spixii from the Cananeia estuary is in accordance with the slight anthropogenic influence in this system, and may be suggestive of the absence of genotoxic and mutagenic effects in these organisms.

THE STABILITY OF FROZEN MINCED AFRICAN CATFISH

The objective of the present study was to evaluate the stability (-18 degrees C) of minced African catfish (MF) for 180 days. Microbiological aspects, lipid oxidation, and total volatile nitrogenous bases (TVB-N) of the MF were determined with and without washing. Washing of the MF caused an increase in moisture content, decrease in proteins, and leaching of the compounds responsible for lipid oxidation. The TVB-N remained stable during the storage period. The microbiological parameters of the MF remained within the legal limits. Thus, a 180-days storage period does not affect the quality of MF and could be a good alternative for the exploitation of this species in Brazil.

Trichomycterus anhanga, a new species of miniature catfish related to T. hasemani and T. johnsoni (Siluriformes: Trichomycteridae) from the Amazon basin, Brazil

Trichomycterus anhanga is described from the Amazon basin, northern Brazil. The species is diagnosed by the latero-sensory system which is restricted to LL1 and LL2, the pectoral fin with two branched rays, the absence of pelvic fins and girdle, the reduced jaws and pharyngeal dentition, the presence of six to seven interopercular odontodes, the absence of a lateral series of spots, the presence of a small dark spot on the ventral surface of the mandibular symphysis, the narrow comma-shaped palatine, the absence of procurrent rays anterior to the dorsal and anal fins, the position of insertion of the first dorsal-fin pterygiophore and the presence of a single pair of pleural ribs. Trichomycterus anhanga shares with T. hasemani and T. johnsoni a wide cranial fontanel which occupies most of the skull roof. Miniaturization as well as synapomorphies for the T. hasemani group are discussed.

A new armored catfish species of the genus Hypostomus Lacepede, 1803 (Siluriformes: Loricariidae) from the upper rio Xingu basin, Brazil

A new armored catfish species of the genus Hypostomus is described from the upper rio Xingu basin, Mato Grosso State, Brazil. The new species is diagnosed from congeners by having high number of teeth (58 to 101, mean 77 on premaxilla, and 58 to 105, mean 80 on dentary), dark spots over body and fins, and abdomen mostly naked. The new species is known from the rapids of the rio Culuene, where it is sympatric with Hypostomus faveolus.

A new species of the catfish genus Trichomycterus from the La Plata River basin, southern Brazil, with comments on its putative phylogenetic position (Siluriformes: Trichomycteridae)

The genus Trichomycterus is a highly diverse group of Neotropical catfishes that encompass almost 60% of all the currently recognized species of the Trichomycteridae. A new species of this genus, T. perkos, is herein described from tributaries of the Paranapanema and Uruguai River basins, southern Brazil. The new species exhibits a remarkable ontogenetic change in its pigmentation, having a unique color pattern when adult. The adult pigmentation consists of three wide dark brown stripes, located in an inner skin layer of trunk and caudal peduncle, combined with a superficial light brown freckled pattern on the dorsum and caudal peduncle. Small, presumably juvenile specimens lack the superficial freckles but already have the dark stripes, thus resembling the color pattern of a few other congeners. Nevertheless, several unequivocal morphological features distinguish both juveniles and adults of T. perkos from these congeners. In spite of the difficulties in estimating phylogenetic relationships within Trichomycterus, the new species is tentatively proposed as being the sister-taxon of a small group of species composed by T. crassicaudatus, T. igobi, and T. stawiarski.

A New Genus and Species of a Minute Suckermouth Armored Catfish (Siluriformes: Loricariidae) from the Rio Tocantins Drainage, Central Brazil: The Smallest Known Loricariid Catfish

Nannoplecostomus eleonorae, a new genus and species of a miniature suckermouth armored catfish, is described based on specimens collected from the karst region of Sao Domingos, upper Rio Tocantins basin, Goias State, central Brazil. The new genus and species can be diagnosed among loricariids by presenting a unique reductive pattern of lateral dermal plates, with most of the body covered by only three series of plates (viz., dorsal, mid-ventral, and ventral). Based on the available published phylogenetic studies for the family, we provisionally consider Nannoplecostomus eleonorae as being an incertae sedis taxon within Loricariidae. Achieving a maximum standard length of 22.2 mm SL, Nannoplecostomus eleonorae is the smallest known loricariid catfish, and a list of the remaining smallest loricariids is provided.

The scent of stress: Pintado catfish differentially respond to chemical cues from stressed conspecifics

We examined whether pintado catfish (Pseudoplatystoma corruscans) can discriminate between scents of non-injured conspecifics stressed by a predator or by confinement and how fish use this information in the trade-off between feeding and predator avoidance. In the confinement stress condition, fish ingested the food, whereas in the predator stress condition, fish did not eat. This finding and comparisons of the latency to food ingestion and the time spent swimming between the confinement and predator-stress conditions indicated that pintado catfish can discriminate between conspecifics stressed by a predator or confinement using chemical cues, and use this information for adjusting the trade-off between food intake and predator avoidance.

Ventilatory responses to skin extract in catfish

The ventilation rate (VR) of an ostariophysan fish, the speckled catfish Pseudoplaty - stoma coruscans, exposed to a chemical alarm cue was measured in the present study in multiple contexts. The influence of the extraction techniques, skin donor food intake and quantity of the alarm cue (skin extract) on this autonomic response was considered. Overall, the catfish VR decreased significantly when exposed to the skin extract (chemical alarm cue) compared with exposure to distilled water (control). No effect of the extraction technique was found. Increasing doses of the skin extract induced a VR reduction of similar magnitude. However, extract obtained from daily-fed fish induced a significant decrease in the VR, whereas extract obtained from foodrestricted fish did not induce any change in the VR. Thus, food intake was associated with the production of a more easily recognizable alarm cue in the speckled catfish. Interestingly, this effect was not related to differences in the number of club cells in the donor catfish epidermis. Dashing, or rapid swimming, a normal component of the alarm response in fish, including this catfish species, was not observed here, and hypoventilation was always associated with no swimming reaction. Together, these results suggest that hypoventilation is a reaction to a chemical alarm cue, likely resulting in improved crypsis, causing the fish to become less easily perceived by a potential predator that usually strikes prey in response to movement.

Life history of three catfish species (Siluriformes: Ariidae) from southeastern Brazil

This study evaluated the spatio-temporal distribution, reproduction and diet of the catfishes Genidens genidens, G. barbus and Aspistor luniscutis in Caraguatatuba Bay. Their sizes were recorded and the sex and reproductive stage identified. The abundance was compared between areas (South and North) and among months (August 2003 - October 2004). The species had different spatial distributions, allowing them to coexist. The temporal distribution reflected their tendencies to migrate in the reproductive period, as evidenced by the dominance of small immature individuals in the bay. G. genidens tended to reproduce in winter, and A. luniscutis in spring. The diet of G. genidens consisted of crustaceans, mollusks (shells), fish scales, ostracods, and bivalve siphons. G. barbus consumed a high proportion of mysids, followed by fish (bones and scales). For A. luniscutis, the diet was based on fish scales and crustaceans. High quantities of particulate organic matter were observed in the diet of all three species, as previously known for estuarine catfishes. The consumption of fish scales may reflect a lepidophagic habit. A small overlap was observed among the diets, reflecting differences in their environments as well as in the proportions of each item ingested.

A new armored catfish species of the genus Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from the upper rio Xingu basin, Brazil

A new armored catfish species of the genus Hypostomus is described from the upper rio Xingu basin, Mato Grosso State, Brazil. The new species is diagnosed from congeners by having high number of teeth (58 to 101, mean 77 on premaxilla, and 58 to 105, mean 80 on dentary), dark spots over body and fins, and abdomen mostly naked. The new species is known from the rapids of the rio Culuene, where it is sympatric with Hypostomus faveolus.

Nuclear abnormalities in erythrocytes and morphometric indexes in the catfish Cathorops spixii (Ariidae) from different sites on the southeastern Brazilian coast

Nuclear abnormalities in erythrocytes (NAE) were taken as biomarkers in the catfish Cathorops spixii (Ariidae) sampled in an estuary little affected by human activity (Cananéia) and in three regions (Santos Channel: SC, Santos Bay: SB and São Vicente Channel: SVC) of the Santos-São Vicente estuary impacted by various anthropogenic activities. Increases in NAE were observed in fish from SC and SVC sampled in the summer period as compared with specimens from the Cananéia estuary. These results suggest the presence of genotoxic compounds in these regions. However, the absence of significant differences in micronuclei frequency reflects slight mutagenic effects in these individuals. It is possible that the lower NAE frequency in specimens from SB might be associated with the greater remobilization and dilution of chemicals in this region. The low frequency of NAE in C. spixii from the Cananéia estuary is in accordance with the slight anthropogenic influence in this system, and may be suggestive of the absence of genotoxic and mutagenic effects in these organisms.