Search

Fishes of the order Siluriformes, known as catfishes, have a global distribution with more than 3,600 valid species of which 2,087 occur in the Neotropical region. Despite being highly diverse, abundant, and of economic importance as food and ornamental fishes, knowledge about the diversity and distribution of their helminth parasites is fragmentary and scarce. Eight species of catfishes (Pterodoras granulosus, Trachydoras paraguayensis, Pimelodella avanhandavae, Loricariichthys platymetopon, Pterygoplichthys ambrosettii, Rhinelepis aspera, Hemisorubim platyrhynchos, and Sorubim lima) from the Aguapeí River, Upper Paraná River basin, municipality of Castilho, São Paulo State, Brazil, were surveyed for helminth parasites. Collected fishes were weighed, measured, and examined for helminth parasites following standard methodology. Fifty helminth parasite taxa (23 monogeneans, 13 digeneans, 11 nematodes, and three cestodes) were found from a total of 405 fishes screened. The helminth taxon that showed the highest mean intensity of infection and mean abundance was the nematode Rondonia rondoni from P. granulosus, followed by the nematode Parasynodontisia petterae from R. aspera. The ecological analyses were carried out at the component community level and at the infracommunity level. Trachydoras paraguayensis had the richest helminth component community. Pterygoplichthys ambrosettii had the most diverse helminth component community and R. aspera had the lowest. Both hosts are loricariids and have similar diet. However, the high parasite diversity of P. ambrosettii is due to the number of dactylogyrids species found (10), which are directly transmitted, whereas only three dactylogyrid species were found in R. aspera. At infracommunity level, the nematode species R. rondoni and P. petterae dominated the parasite communities. This study presents 38 new host records, contributing considerably to increase the diffuse knowledge of helminth parasites of Neotropical siluriforms., Graphical abstract Image 1, Highlights • Fifty helminth parasite taxa were recovered from 405 catfishes surveyed. • Monogenea was the most diverse group, representing 46% of the helminth taxa found. • Thirty-eight new host records are presented.

The ventricle of the fish heart is a chamber that exhibits great morphological and vascular variability among species. However, although the Neotropical region has the greatest taxonomic and functional diversity in freshwater fish, many considerations have been formed without previous knowledge of the ventricular morphology of these fishes. Thus, the purpose of the present study was to describe the anatomy, myoarchitecture, and distribution of coronary vessels in the ventricle of three species belonging to two representative groups from this geographical area, Leporinus elongatus, Hoplias malabaricus (Characiformes) and Pterodoras granulosus (Siluriformes), using gross anatomy and light microscopy. The species L. elongatus and H. malabaricus presented a pyramidal ventricle associated to a mixed myocardium, formed by compact and spongy layers. The mixed myocardium was also observed in P. granulosus, but associated with a sac-like ventricle. The compact layer of the species studied was formed by muscular bundles in longitudinal and circular disposition. The spongy layer constituted most of the ventricular myocardium and was formed by a complex network of trabecular sheets presenting muscle fibers also in longitudinal and circular disposition. Coronary vessels were present in the three species and were observed primarily on the surface of the bulbus arteriosus, later branching on the ventricular surface and penetrating the myocardium only at the compact layer level. These characteristics allow classification of the ventricles studied as type II. Although the type I ventricle is the most common type in teleosts, it is important to emphasize that this type has not been observed in any Neotropical freshwater teleosts studied to date.

Fil: Takagui, Fábio Hiroshi. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Dias, Ana Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Olivan Birindelli, José Luís. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología animal y vegetal. Museo de Zoología; Brasil. Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología. Laboratorio de Histología y Genética; Brasil. Fil: Da Rosa, Renata. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Lui, Roberto Laridondo. Universidad del Oeste de Paraná. Centro de Ciencias Biológicas y de la Salud. Laboratorio de Citogenética; Brasil. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética. Laboratorio de Citogenética General; Argentina. Fil: Giuliano-Caetano, Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. The family Doradidae (Siluriformes) is an important group of fishes endemic to freshwater ecosystems in South America. Some cytogenetic studies have been conducted focused on the group; however, there are no reports on the occurrence of B chromosomes for the family. In this paper the chromosomal characteristics of Platydoras armatulus (Valenciennes, 1840), Pterodoras granulosus (Valenciennes, 1821) and Ossancora punctata (Kner, 1855) were investigated through classical cytogenetics approaches. The conventional staining reveals 2n=58 in Platydoras armatulus and Pterodoras granulosus, however with distinct karyotypic formulae, possibly originated by pericentric inversions. In Ossancora punctata a derivate karyotype was described with 2n=66 and predominance of acrocentric chromosomes. The C banding pattern was resolutive in discriminating the three species, being considered an important cytotaxonomic marker. All species showed B chromosomes totally heterochromatic with non-Mendelian segregation during meiosis and low frequencies in mitotic cells. The probably origin of these additional elements was through fragmentations of chromosomes of the standard complement, which occurred recently and independently in these three species. The diploid number observed in O. punctata is an evidence of centric fusions and up to the moment it is the highest diploid number reported for Doradidae.

The first molecular assessment of phylogenetic relationships of cladorchiid digeneans (superfamily Paramphistomoidea Fischoeder, 1901) from freshwater fishes based on 28S rDNA, ITS2 and cox1 sequences reveals the subfamilies Dadayiinae Fukui, 1929 and Kalitrematinae Travassos, 1933 as non-monophyletic, whereas Dadaytrema Travassos, 1931 represented by three species is monophyletic. Fourteen species of cladorchiids were found in characiform, perciform and siluriform fishes in the Neotropical Region (Brazil and Peru), with numerous new host and geographical records. The first scanning electron micrographs of seven species are presented. Two new species of dadayiine and one new species of kalitrematine paramphistomes are described. Microrchis macrovarium sp. n. from Pimelodella cristata (Müller et Troschel) (type host), Tetranematichthys quadrifilis (Kner) and Pterodoras granulosus (Valenciennes) in Brazil and Peru differs from all three congeners in that the testes are directly tandem, not oblique, and that the ovary, between the caecal ends, is widely separated from the testes. Pronamphistoma philippei sp. n. from Heros sp. in Brazil is distinguished from the type and only species, Pronamphistoma cichlasomae Thatcher, 1992, by the absence of the anterior collar-like expansion present in the type species, the presence of extramural rather than intramural pharyngeal sacs, and the unusual development of the dorsal and ventral exterior circular muscle fibre series in the acetabulum. Pseudocladorchis romani sp. n. from P. granulosus (type host), Brachyplatystoma vaillantii (Valenciennes), Calophysus macropterus (Lichtenstein), Megalodoras uranoscopus (Eigenmann et Eigenmann) and Oxydoras niger (Valenciennes) in Brazil and Peru, is most similar to Pseudocladorchis nephrodorchis Daday, 1907 but differs in the shape of the testes (irregular, versus reniform in the latter species) and the size of the ovary (as large as, or larger than, the testes in the new species). The generic diagnosis of Pronamphistoma Thatcher, 1992 is amended. Dadaytremoides parauchenipteri Lunaschi, 1989 is transferred to Doradamphistoma Thatcher, 1979 as D. parauchenipteri (Lunaschi, 1989) comb. n. based on morphological and molecular evidence.

This study assessed the quality of vegetation cover in the Parque Estadual das Varzeas do Rio Ivinhema (PEVRI, Upper Parana River basin, MS, Brazil), the concentration of metals (Cd, Pb, Cr, Cu, Fe, Zn and Ni) in water and muscle and hepatic tissues of five fish species collected in the PEVRI – Hemiodus orthonops, Leporinus friderici, Prochilodus lineatus, Pterodoras granulosus and Pimelodus maculatus – in addition to non-carcinogenic risk assessment and genotoxicity potential in these species. Regarding vegetation index, we found that only 26.25% of the PEVRI area is occupied by denser vegetation. In the sites analyzed, Cd, Cu, Fe and Ni showed high concentrations in water, above the reference values established by the legislation. In the muscle and hepatic tissues of the fish species analyzed, Cd and Pb values exceeded the reference limits. The genotoxic alterations identified in erythrocytes of the fish species studied were nuclear invagination, nuclear budding, picnosis, binucleated cell and lobulate nucleus. For the non-carcinogenic risk assessment in fish, Cd and Pb presented values greater than 1, indicating risk in the consumption of these fish. In the bioaccumulation factor, Cd and Pb were greater than 100 in all fish species analyzed, except for Pb in L. friderici. The results indicated that the water resources of the PEVRI are being affected by some type of contaminant, probably due to anthropic activities carried out around the park or carried from the upper portions of the basin through the drainage system.

GASPAR DA LUZ, Karla Danielle; FUGI, Rosemara; ABUJANRA, Fabiane; AGOSTINHO, Angelo Antonio. Alterations in the Pterodoras granulosus (Valenciennes, 1833) (Osteichthyes, Doradidae) diet due to the abundance variation of a bivalve invader species in the Itaipu Reservoir, Brazil. Acta Scientiarum, Maringá, v. 24, n.2, p.427-432, 2002. Disponível em: http://www.eduem.uem.br/acta/bio/2002/22_270_01.pdf Variations in the diet of Pterodoras granulosus (Osteichthyes, Doradidae) were evaluated from 1994 to 1998 taking into account two events that affected the abundance of an introduced bivalve Corbicula fluminae: (i) the abundance explosion of the bivalve in the reservoir, started in 1994 and (ii) the slaughter of the bivalve population due to fluctuations in water level, started in July 1996. Stomach contents were analyzed and results were shown considering the methods of frequency of occurrence and volumetric, combined in an alimentary index (AI). In 1994, 1995 and 1996 C. fluminae was the most consumed item, constituting about 90% of the diet. A decrease of this item intake (39%) was verified in 1997, with an increase of the vascular plants intake (26%). The diet of P. granulosus changed drastically in 1998, when it became based on algae (49%) and vascular plants (45). These results indicate the important role played by water level fluctuations in reservoirs, on the food availability for P. granulosus. Resumo: Foram avaliadas as alterações na dieta de Pterodoras granulosus (Osteichthyes, Doradidae), no reservatório de Itaipu, no período de 1994 a 1998, associadas às alterações na abundância de um bivalve invasor, Corbicula fluminea, considerando-se dois eventos: (i) a explosão de C. fluminea no reservatório a partir de 1994, e (ii) a mortandade desse bivalvia em função das flutuações do nível de água a partir de julho/96. Os conteúdos estomacais, foram analisados pelos métodos de ocorrência e volumétrico, combinados no Índice Alimentar. A análise mostrou que C. fluminea foi o principal alimento nos anos de 94/95/96, representando aproximadamente 90% da dieta. Em 1997, houve uma queda no consumo de C. fluminea (39% da dieta), concomitante a um incremento no consumo de vegetal (26%), enquanto no ano de 98 a dieta foi composta basicamente por algas filamentosas (49%) e vegetal superior (45). Estes resultados evidenciam a importância da flutuação do nível da água em reservatórios sobre a disponibilidade alimentar de P. granulosus. Foram avaliadas as alterações na dieta de Pterodoras granulosus (Osteichthyes, Doradidae), no reservatório de Itaipu, no período de 1994 a 1998, associadas às alterações na abundância de um bivalve invasor, Corbicula fluminea, considerando-se dois eventos: (i) a explosão de C. fluminea no reservatório a partir de 1994, e (ii) a mortandade desse bivalvia em função das flutuações do nível de água a partir de julho/96. Os conteúdos estomacais, foram analisados pelos métodos de ocorrência e volumétrico, combinados no Índice Alimentar. A análise mostrou que C. fluminea foi o principal alimento nos anos de 94/95/96, representando aproximadamente 90% da dieta. Em 1997, houve uma queda no consumo de C. fluminea (39% da dieta), concomitante a um incremento no consumo de vegetal (26%), enquanto no ano de 98 a dieta foi composta basicamente por algas filamentosas (49%) e vegetal superior (45). Estes resultados evidenciam a importância da flutuação do nível da água em reservatórios sobre a disponibilidade alimentar de P. granulosus.

HAHN, Norma Segatti; MONFREDINHO JÚNIOR, Aldo; FUGI, Rosemara; AGOSTINHO, Angelo Antonio. Aspectos da alimentação do armado, Pterodoras granulosus (Ostariophysi, Doradidae) em distintos ambientes do alto rio Paraná. Revista Unimar, Maringá, v.14, supl., p.163-176, 1992. The diet and feeding activity of Perodoras granulosus were studied by means of stomachs of individuals captured in montly samples in Itaipu reservoir, in its left bank tributaries and in a flood plain in the High Parana River, in the region near Porto Rico/PR - Nova Andradina/MS. The results showed clearly that this species uses a huge variety of food kinds in its diet, with predominance of high plants, mainly among bigger individuals. As far as alimentary activity is concerned, it was regular and higher during the year, among fishes caught in Porto Rico - Nova Andradina, whereas among the individuals from Itaipu reservoir and its tributaries, this activity was higher in Autumn. Para estudo da dieta e atividade alimentar de Pterodoras granulosus, foram utilizados estômagos de indivíduos obtidos em coletas mensais, realizadas no reservatório de Itaipu, seus tributários da margem esquerda e na planície de inundação do rio Paraná, região de Porto Rico/PR - Nova Andradina/MS. Os resultados evidenciaram que esta espécie utiliza, em sua dieta, ampla variedade de tipos de alimento, com predomínio de vegetais superiores, principalmente entre indivíduos de grande porte. Considerando-se a atividade alimentar, verificou-se que esta foi mais intensa e mais regular, durante o ano, entre os peixes coletados em Porto Rico, enquanto que entre os exemplares do reservatório de Itaipu e tributários esta atividade foi mais acentuada no outono. Abstract: The diet and feeding activity of Perodoras granulosus were studied by means of stomachs of individuals captured in montly samples in Itaipu reservoir, in its left bank tributaries and in a flood plain in the High Parana River, in the region near Porto Rico/PR - Nova Andradina/MS. The results showed clearly that this species uses a huge variety of food kinds in its diet, with predominance of high plants, mainly among bigger individuals. As far as alimentary activity is concerned, it was regular and higher during the year, among fishes caught in Porto Rico - Nova Andradina, whereas among the individuals from Itaipu reservoir and its tributaries, this activity was higher in Autumn.

Pterodoras granulosus (Valenciennes, 1821) Fig. 20 Body deep; greatest body depth contained 2.9 to 4.4, head length 3.4 to 4.4 times in SL; snout length contained 2.2 to 2.3, horizontal orbital diameter 8.3 to 11.8 and least interorbital width 2.5 to 3.1 times in HL; orbital diameter contained 3.1 to 4.3 times in interorbital width. Mouth terminal; with dentigerous plates in both premaxilla and dentary. Lateral line with 27-28 plates. Dorsal fin with I,6, pectoral fin with I,8- 10, pelvic fin with 7 and anal fin with 12 or 13 rays. Ground color pale brown to greyish, darker dorsally, lighter ventrally; dark-brown or grey chromatophores irregularly distributed on body. Dark-brown or yellowish fins (Graça, Pavanelli, 2007). Maximum standard length. 635.0 mm (Graça, Pavanelli, 2007). Distribution. Amazon, río Paraná and coastal drainages of Guyana, Surinam and French Guiana. Remarks. Pterodoras granulosus is a non-native species from the upper rio Paraná, and its occurrence can be associated with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls., Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 66, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Pavanelli CS, Graca WJ, Zawadzki CH, Britski HA, Vidotti AP, Avelino GS, Verissimo S. Fishes from the Corumba Reservoir, Paranaiba River drainage, upper rio Parana basin, State of Goias, Brazil. Check List. 2007; 3 (1): 58 - 64."]}

Heavy metals concentration in fishes are important indicator geomorphological or environmental integrity in aquatic habitats. Aiming to evaluate metal concentration in fish muscles in Apa River, upper Paraguay basin, we analyzed 124 individuals of eight fish species at Cachoeira do Apa district (Porto Murtinho) from 2013 to 2014 belonging to Brycon hilarii, Leporinus friderici, Megaleporinus macrocephalus, Megaleporinus obtusidens, Piaractus mesopotamicus, Prochilodus lineatus, Pterodoras granulosus and Salminus brasiliensis. The samples were frozen and in the laboratory the musculature was removed, the samples were digested using the triacid method, and later the concentration of heavy metals was quantified in a flame atomic absorption spectrophotometer. There is a significant difference in the concentration of metals in fish (F=27.79, pf studied species, we observed that P. lineatus have a more different pattern of metal concentration, with P. granulosus also presenting a different pattern of others species. None species presented the concentration of metals above the limit defined by Brazilian legislation, however, species differed in their metal concentrations according to the position in the water column and feeding, suggesting that the integrated assessment of the concentration of metals may be an indicator of ecological differences in the obtaining of resources by species in aquatic communities. DOI: http://dx.doi.org/10.17807/orbital.v10i1.1040

A região no entorno de Barcarena, se destaca na pesca artesanal e na elevada dependência da população em relação aos recursos pesqueiros. Deste modo, o presente estudo objetiva apresentação de um levantamento e estimativa de parâmetros ecológicos da ictiofauna nas proximidades da Vila de Itupanema - Barcarena. As amostras foram realizadas em duas campanhas ocorridas em março e setembro de 2008, com intuito da caracterização nos períodos chuvoso e menos chuvoso na região. Foram definidas sete estações de coleta nas proximidades da Ilha do Meritizal, ao longo do canal principal do rio Pará, acerca da localidade de Itupanema. Foram utilizadas redes com malhas 25, 30 e 35 mm para as pescarias do tipo armadilha, tapagem e arrasto. Após o recolhimento dos apetrechos de pesca, os indivíduos foram separados por espécie e quantificados. Um exemplar de cada espécie foi conservado em caixa isotérmica, com gelo e devidamente etiquetado para posterior identificação, e transportados para o laboratório onde foram identificados utilizando classificações sistemáticas. Os parâmetros analisados para levantamento da ictiofauna foi: Frequência, Riqueza, Índice de Simpson e Índice de Shannon. A diversidade das espécies capturadas foi similar ao longo das campanhas realizadas. Contudo, a família Scianidae foi a que apresentou maior quantidade de espécies por família em ambos os períodos analisados. E se verificou ainda, a existência de três espécies dominantes que foram Pterodoras granulosus, Geophagus obscurus e Plagioscion squamosissimos. Palavras-chave: ictiofauna, porto graneleiro de Barcarena, biodiversidade. DOI: http://dx.doi.org/10.18561/2179-5746/biotaamazonia.v5n3p72-77

Vallone, E.R., Vezzosi, R.I. & Cione, A.L. February 2017. First fossil fish (Teleostei, Siluriformes) from the Late Pleistocene of Santa Fe Province, Argentina. Alcheringa 00, 000–000. ISSN 0311-5518. The record of fossil fish from the Pleistocene of Argentina is poor. Here we describe the first ichthyofauna from Late Pleistocene riverbank beds in the Salado River of Santa Fe Province, Argentina. The material consists of isolated pectoral and dorsal fin spines, together with skull fragments. Four species-level taxa referable to three families can be identified: Pterodoras granulosus (Doradidae), Pimelodus cf. maculatus and Pimelodus cf. albicans (Pimelodidae) and cf. Hypostomus sp. (Loricariidae). Specimens attributed to Pterodoras granulosus and Pimelodus maculatus represent a minimum age for origin of these taxa. The Salado River assemblage includes the richest record of Pleistocene catfishes yet documented from southern South America. Evelyn Romina Vallone [evelynvallone@conicet.gov.ar] and Raúl Ignacio Vezzosi [vezzosiraul@gmail.com], Laboratorio de Paleontología de Vertebrados, CICYTTP-CONICET, Materi y España, (3105) Diamante, Entre Ríos, Argentina; Alberto Luis Cione [acione@museo.fcnym.unlp.edu.ar], División Paleontología de Vertebrados. Museo de La Plata. Paseo del Bosque s/n, (1900) La Plata, Argentina. Fil: Vallone, Evelyn Romina. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Vezzosi, Raúl Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Cione, Alberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina

This study evaluated the relationship between the young of year (YOY) abundance of migratory fish species and the interannual variations in the duration and delay of floods in the Upper Parana River floodplain. YOY of the most abundant migratory species Brycon orbignyanus, Hemisorubim platyrhynchos, Leporinus elongatus, Leporinus macrocephalus, Leporinus obtusidens, Pseudoplatystoma corruscans, Pterodoras granulosus, Prochilodus lineatus, Salminus brasiliensis and Sorubim lima were studied in a stretch of the Parana river influenced by dams. Multiple regression analyses were performed with flood duration and delay as predictors for YOY abundances. There were differences among the species in the responses to flood duration and delay. The species B. orbignyanus, L. elongatus, L. macrocephalus, L. obtusidens, and P. lineatus exhibited an exponential increase in YOY abundance with flood duration. An exponential decrease in YOY abundance with flood delay was found for most of the studied species. Nevertheless, flood delay and flood duration were significant predictors of YOY abundance for L. elongatus, L. obtusidens, P. corruscans and P. lineatus. For these species, flood delays may result in failure of recruitment because these species migrate early in the season to adjust their energy reserves and their swimming patterns. Therefore, any efforts to preserve migratory fish should consider discharge manipulation from reservoirs upstream of the study areas. It is crucial that reservoirs are operated in such a way that the quantity, duration and timing of water release are compatible with the viability of spawning and the survival of early life stages of migratory fish.

deMeloGermano,R.,Stabille,S.R.,deBrittoMari,R.,Pereira,J.N.B.,Faglioni, J.R.S. and de Miranda Neto, M.H. 2014. Morphologicalcharacteristics of the Pterodoras granulosus digestive tube (Valenciennes, 1821)(Osteichthyes, Doradidae). — Acta Zoologica (Stockholm) 95: 166–175.Little is known about the digestive tube (DT) morphology of the fish Pterodorasgranulosus. Therefore, macro-, meso-andmicroscopicaspectsof15 P. granulosusDTs were analysed. The muscular layer was composed of striated skeletal mus-cle in the oesophagus and smooth muscle i n the other segments. The epitheliumprogressed from a stratified pavement in the oesophagus to a simple column inthe other segments, with a flat striated border in the intestine. A large number ofmucus-secreting periodic acid-Schiff (PAS)-positive cells were observed in theoesophagus. In the stomach, the number of glands in the region decreasedtowards the cardiac–fundic region, and none were found in the pylorus. Theintestine showed an epithelium with absorptioncellsandanincreasingnumberof PAS-positive caliciform cells towards the distal region. Tests showed that theoesophagus is adapted for passing and preparing food for the chemical digestionthat occurs in the stomach, which also has storage functions without grindingaction. The proximal intestinal region was consistent with fat absorption, andthe medium region, with the absorption of other nutrients. The distal region wasshort and consistent with a role in absorption for osmoregulation as well as inthe formation, storage and disposal of faeces.Ricardode Melo Germano, Departamento de Ci^enciasMorfologicas, Universid-ade Estadual de Maringa, Av. Colombo, no. 5790 –Bloco H79 –CEP. 87020-900, Maringa –Parana, Brasil. E-mail: prof.ricardogermano@gmail.comIntroductionThroughout the evolutionary process, fish have developedtheir own mechanisms to obtain food and to survive, with spe-cific physiological and morphological changes of the digestivesystem associated with their feeding behaviour (Dzhumaliyev1982; Fanta et al. 2001).In general, the digestive tubes of fish present the classicstratigraphic organisation that is described for the tubularorgans of other vertebrates. However, the macro- and micro-scopic structures of the segments are indicative of the fairlyprecise nature of the fish diet and how food is ingested by thespecies (Chaves and Vazzoler 1984; Seixas-Filho et al. 2000;Fugi et al. 2001). These factors have led to the appearance ofmorphological changes from the oesophagus to the distalintestine, which can be used to distinguish fish structures fromclassical descriptions.Pterodoras granulosus, described by Valenciennes in 1821(Fowler 1951) and popularly known as ‘armado’, ‘armadocomum’ or ‘abotoado’, belongs to the Siluriformes order,Doradidae Family and is found in the basins of the Paran a,Paraguay, Uruguay, Amazonas and Goias rivers. This specieswasnotfoundintheupperParana River and its floodingchannels until the construction of the Itaipu reservoir andwater levelling, when the P. granulosus increased its distribu-tion (Agostinho et al. 2003; Feitoza et al. 2004).

Determining quality of food ingested and digestibility can be helpful in understanding the mechanisms that determine trophic plasticity, which is the ability of a given species to use a more advantageous food source at a given time. In this study, the chemical composition and digestibility of food ingested by various trophic fish groups at different sites of the Upper River Paraná floodplain are evaluated. Specimens of Pseudoplatystoma corruscans, Prochilodus lineatus, Leporinus friderici, Pterodoras granulosus and Schizodon borellii from the Baía, Ivinheima and Paraná Rivers and from Fechada and Ventura Lagoons were taken as samples (3-16cm-mesh net). Volume participation analyses of food items were determined and contents from the stomach and the intestine’s latter quarter were removed for bromatological analysis (energy, crude protein, ash and dry matter). Internal marker acid- insoluble ash was employed for apparent digestibility coefficients. P. lineatus and P. corruscans had an intake with lower and higher energy and crude protein contents, respectively. P. corruscans had slight variations in food items and composition, whereas P. granulosus had the greatest variation. Whereas P. lineatus had the highest apparent digestibility coefficients in energy, S. borellii showed least variation in diet. P. granulosus and P. lineatus had the higher percentages of dry matter in the stomach in the Paraná River, whereas P. corruscans had similar use in the Baía Rivers and Ventura Lagoon. S. borellii showed low utilization of germanous energy. It may be concluded that the site determined the variation in quality and use of diet by L. friderici, P. granulosus and S. borellii. The generalist species L. friderici demonstrated a good use of different food items ingested at the site; likewise, the generalist species P. corruscans had a similar diet and the same use of food. Rev. Biol. Trop. 59 (1): 85-101. Epub 2011 March 01.Determining quality of food ingested and digestibility can be helpful in understanding the mechanisms that determine trophic plasticity, which is the ability of a given species to use a more advantageous food source at a given time). El objetivo de este estudio fue evaluar la composición química y la digestibilidad de los alimentos consumidos por los peces de los diferentes grupos tróficos en diferentes lugares de la llanura de inundación del alto río Paraná. Fueron colectados (red 3 a 16cm de tela) individuos de Pseudoplatystoma corruscans, Prochilodus lineatus, Leporinus friderici, Pterodoras granulosus y Schizodon borellii en los ríos Baía (Rbai) Ivinheima (RIvi) y Paraná (RPar), lagunas Fechado (LFec) y Ventura (LVen). Se realizaron análisis de la participación en volumen de elementos alimentarios como contenido estomacal y el contenido de la cuarta parte final del intestino fue removido para análisis bromatológicos (energía, proteína, cenizas y materia seca). Se determinaron los coeficientes de digestibilidad aparente (CDA) utilizando las cenizas insolubles en ácido como marcador interno. P. lineatus y P. corruscans consumieron alimentos con menores y mayores contenidos de energía y proteína bruta, respectivamente con P. corruscans teniendo poca variación en los elementos y en la composición del alimento, mientras que PG presentó la mayor variación de estos. P. lineatus tuvo mejores CDA de la energía y S. borellii presentó la menor utilización de energía alimentaria. P. granulosus y P. lineatus tuvieron un mejor uso del alimento en el RPar y P. corruscans presentó aprovechamiento similar en el RBai y Lven. Schizodon borellii tuvo bajo aprovechamiento de la energía proveniente de las gramíneas. Se concluye que L. friderici, P. granulosus e S. borellii presentaron variación en la calidad y en el aprovechamiento del alimento consumido debido a los subsistemas. El L. friderici, especie generalista, presentó buena utilización de los diferentes alimentos consumidos en los subsistemas, mientras que P. corruscans, especialista, tenía una dieta similar y el mismo aprovechamiento.

Summary Length–weight relationships (LWR) were estimated for 12 species, representing three orders and eight families of fishes from the Parana and Uruguay rivers in Argentina: Acestrorhynchus pantaneiro, Cynopotamus argenteus, Pachyurus bonariensis, Pterodoras granulosus, Hypostomus commersoni, Pseudoplatystoma corruscans, Pimelodus maculatus, Parapimelodus valenciennis, Salminus brasiliensis, Prochilodus lineatus, Hoplias malabaricus and Leporinus obtusidens. For the last four species, the length at first spawning (Lm) was estimated using three different methods. The captures were made in shallow river areas during 2005–2013. Significant length–weight relationships were found for all species. None or few LWRs were previously available for these species.

By means of the analysis of 28 modern individuals of Pterodoras granulosus, a silurid of great importance in the archaeological assemblages of the Amazonas and Parana basins, allometric equations based on the size of the spines have been derived, allowing the reconstruction of size profile and weight of the individuals recovered in fossil assemblages. These equations have been obtained from four different measures, three of them related to different sections of the spine articulation with the cleithrum, an area that usually has an excellent preservation in the archaeological and palaeontological records. This study allows observation of remarkable individual variability of the captured specimens regarding its total weight, mainly due to the weight variability of viscera, and also probably with other metabolic situations, episodic intakes and/or reproductive aspects, among others. Hence, allometric equations determine more accurately length than weight, resulting in proxy data for the reconstruction of different size profiles of archaeological assemblages. Copyright © 2010 John Wiley & Sons, Ltd.

– Diet composition of Pterodoras granulosus was investigated from June 2004 to June 2005 in the Upper Parana River floodplain, following invasion by two mollusc species Corbicula fluminea and Limnoperna fortunei. Stomach and intestinal contents analysis showed spatial differences in the diet composition. In the Baia River, P. granulosus diet consisted mainly of C. fluminea, whereas plant items dominated in the Ivinheima River, and L. fortunei was the most important food in the Parana River. There was little selectivity in shell length consumed. In spite of C. fluminea being a larger mollusc, L. fortunei appears to be energetically more profitable because its shell is more fragile and is rapidly opened and digested. A considerable amount of closed shells of C. fluminea at the end of the digestive tract points to a possible role of P. granulosus as a mollusc disperser.

– We studied the migratory behaviour of armado, Pterodoras granulosus, in the Parana River Basin of Brazil, Paraguay and Argentina, during 1997–2005. This species invaded the Upper Parana River after upstream dispersal was facilitated when Itaipu Reservoir inundated a natural barrier. Fish were tagged (N = 8051) in the mainstems of the Yacyreta and Itaipu reservoirs, bays of major tributaries, the Parana River floodplain above Itaipu Reservoir, and below dams. In all, 420 fish were recaptured of which 61% moved away from the release area. Fish moved a maximum of 215 km (mean 42), and at a maximum rate of 9.4 km·day−1 (mean 0.6). Of the 256 armados that moved away from the release site, 145 moved upstream towards unimpounded stretches of the Parana River and 111 moved downstream into the reservoir and bays of its tributaries (maximum 150 km). Based on the observed migratory movements, we suspect that most of the reproductive output originates in tributaries to the reservoirs. The ability of this species to expand its range presents a conundrum by pitting fishery management interests against conservation needs. Maintenance of the important armado fisheries depends on the ability of the species to migrate freely to use spawning and nursery areas in reservoir tributaries and floodplains. However, its ability to migrate long distances can allow this non-native species the opportunity to invade most of the Upper Parana River.

This article provides the first data on the occurrence of adult proteocephalidean tapeworms (Cestoda) in freshwater fishes from the Peruvian part of the Amazon River. In total, 29 species of proteocephalidean cestodes of the genera Amphoteromorphus, Chambriella, Choanoscolex, Euzetiella, Houssayela, Mariauxiella, Monticellia, Nomimoscolex, Nupelia, Peltidocotyle, Proteocephalus, Rudolphiella, Scholzia, Sciadocephalus, Spatulifer, Travassiella, and Zygobothrium are reported from 10 species of pimelodid, heptapterid and doradid catfish and the cichlids Astronotus ocellatus and Cichla monoculus. All species are reported from western Amazonia and Peru for the first time, with 6 taxa representing new geographical records for the Amazon River basin. The most remarkable finding is that of Houssayela sudobim (Woodland, 1935) from Pseudoplatystoma fasciatus, reported for the first time since its original description. Four other taxa (Chambriella sp. and Proteocephalus sp. from Phractocephalus hemioliopterus, Nupelia sp. from Goeldiella eques, and Proteocephalus sp. from Pterodoras granulosus) may be new for science. A list of the species found is provided together with brief comments on their fish hosts and geographical distribution. In addition to adult tapeworms, larvae (metacestodes) of proteocephalideans were found encysted in the mesenteries, intestinal wall, and gills of small catfish.

Summary The diet of seven fish species from the Rio de la Plata was studied to evaluate their behaviour as predators on the invasive bivalves Corbicula fluminea and Limnoperna fortunei. It was concluded that the teleosts Pterodoras granulosus, Pimelodus maculatus, Paraloricaria vetula and Ricola macrops prey upon C. fluminea, whilst Leporinus obtusidens, Rhinodoras dorbignyi and Brochiloricaria chauliodon feed on Lim. fortunei. These fish species had altered their diets to consume large amounts of these molluscs. Three of the fishes recorded here were previously unknown to feed on molluscs. The fishes studied here prey upon molluscs that ingest trace metals with their food items, thus monitoring the situation is suggested as several of these fish species are caught for human consumption.

Objetiva-se avaliar o efeito da carga parasitária de Rondonia rondoni sobre o fator de condição de armados, Pterodoras granulosus. Foram necropsiados 51 espécimes de armados, coletados no rio Paraná (Porto Rico/Paraná). Para as análises, utilizaram-se os testes de “t”, de Student, para determinar se o comprimento dos hospedeiros machos e fêmeas eram semelhantes; “U”, de Mann-Whitney, para determinar o efeito do sexo do hospedeiro na intensidade de infecção da espécie de parasito; “G” Log-likelihood, para determinar o efeito do sexo do hospedeiro na prevalência do parasito; coeficiente de correlação (CC) “r”, para determinar a correlação entre o comprimento do hospedeiro e a prevalência de infecção; CC por postos de Spearman “rs”, para determinar as possíveis correlações entre a intensidade de infecção e a diversidade parasitária com o comprimento do hospedeiro e para verificar a correlação entre a intensidade parasitária e o fator de condição (K). Os resultados permitiram concluir que, apesar das variações no comprimento entre machos e fêmeas, o sexo não influencia na intensidade e na prevalência de infecção. Porém a intensidade de parasitismo e a prevalência aumentaram com o incremento do comprimento do hospedeiro, e a intensidade parece não afetar o fator de condição de armado, o qual parece estar em equilíbrio com esse parasita nesse ambienteAiming to evaluate the effect of parasitic load of Rondonia rondoni over the condition factor of Pterodoras granulosus. Fifty one specimens of P. granulosus were collected in Paraná River, (Porto Rico/Paraná). To analyze were used: Student’s “t”, to determine if length of hosts males and females were similar; Mann-Whitney test “U”, to determine the effect of sex of host on the intensity of infestion of the parasite; “G” Log-likelihood test, to determine the effect of sex of the host on the prevalence of parasite; coefficient of correlation “r”, to determine the correlation between the length of host and the prevalence of infection; Spearman rank correlation coefficient “rs”, to determine as possible correlation’s between the intensity of infection and the parasitic diversity with the length of the host, and to examine the correlation between the parasitic intensity and the condition factor (K). Based in this results we conclude, that despite of variations in the length, between males and females, the sex does not influence in the intensity and prevalence of infection. However, the intensity of parasites and the prevalence of R. rondoni increased with the length of host being that, the intensity does not affect the condition factor of Pterodoras granulosus, which mean to be in equilibrium with the parasite in this local

Foram utilizados 1033 exemplares de Pterodoras granulosus (Siluriformes, Doradidae), 512 machos e 521 fêmeas coletados no reservatório de Itaipu, Estado do Paraná. A idade individual foi estimada a partir dos anéis etários encontrados nas vértebras. O número máximo de anéis encontrados nas vértebras para o período estudado foi 10 para ambos os sexos. Os anéis encontrados nas vértebras são anuais e formados em novembro, como o observado através da análise da variação temporal do incremento marginal médio, possivelmente resultado do início do período reprodutivo. A curva de crescimento expressa pelo modelo de von Bertalanffly, usando o procedimento não-linear, é Ls =48,57 [1-e-0,16(t+1,83)] para machos; e Ls = 65,06 [1-e-0,11(t+1,87)] para fêmeas, na qual o comprimento padrão é dado em centímetro e a idade em anosA total of 1033 individuals of Pterodoras granulosus (512 males and 521 females) were collected in Itaipu Reservoir. Individual age was estimated through the rings found in the vertebrae. In the period studied, the highest number of rings found was 10 for both sexes. The rings are annual and formed in November, as observed in time variation analysis of marginal increment, possibly resulted from the reproductive period beginning. The growth curve, expressed through Von Bertalanffy model, using the nonlinear procedure, is: Ls=48,57[1-e-0,16(t+1,83)] for males and Ls= 65,06[1-e-0,11(t+1,87)] for females, in which the standard length is given in centimeters and the age in years

Foram avaliadas as alterações na dieta de Pterodoras granulosus (Osteichthyes, Doradidae), no reservatório de Itaipu, no período de 1994 a 1998, associadas às alterações na abundância de um bivalve invasor, Corbicula fluminea, considerando-se dois eventos: (i) a explosão de C. fluminea no reservatório a partir de 1994, e (ii) a mortandade desse bivalvia em função das flutuações do nível de água a partir de julho/96. Os conteúdos estomacais, foram analisados pelos métodos de ocorrência e volumétrico, combinados no Índice Alimentar. A análise mostrou que C. fluminea foi o principal alimento nos anos de 94/95/96, representando aproximadamente 90% da dieta. Em 1997, houve uma queda no consumo de C. fluminea (39% da dieta), concomitante a um incremento no consumo de vegetal (26%), enquanto no ano de 98 a dieta foi composta basicamente por algas filamentosas (49%) e vegetal superior (45). Estes resultados evidenciam a importância da flutuação do nível da água em reservatórios sobre a disponibilidade alimentar de P. granulosus.Variations in the diet of Pterodoras granulosus (Osteichthyes, Doradidae) were evaluated from 1994 to 1998 taking into account two events that affected the abundance of an introduced bivalve Corbicula fluminae: (i) the abundance explosion of the bivalve in the reservoir, started in 1994 and (ii) the slaughter of the bivalve population due to fluctuations in water level, started in July 1996. Stomach contents were analyzed and results were shown considering the methods of frequency of occurrence and volumetric, combined in an alimentary index (AI). In 1994, 1995 and 1996 C. fluminae was the most consumed item, constituting about 90% of the diet. A decrease of this item intake (39%) was verified in 1997, with an increase of the vascular plants intake (26%). The diet of P. granulosus changed drastically in 1998, when it became based on algae (49%) and vascular plants (45). These results indicate the important role played by water level fluctuations in reservoirs, on the food availability for P. granulosus.

Fil: Villar, Carlos. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Limnologia ; Argentina

A new anisakid nematode, Raphidascaroides brasiliensis n. sp., is described from the intestine of the freshwater thorny catfish Pterodoras granulosus (Valenciennes) (Doradidae, Siluriformes) from Amazonia (Manaus), Brazil. It is characterised mainly by the smooth, almost rounded tail tip in both sexes, the length of the spicules (0.952–1.183 mm) and by the number and arrangement of the caudal papillae (24–34 pre-anal, 1 adanal and 5 postanal pairs and 1 median pre-anal papilla) in the male. It is the first Raphidascaroides species described from South America and the second species of this genus reported from a freshwater fish.

This study characterized the morphological differences among migratory fish species from the Paraná River Basin. A total of 177 adult fish of Leporinus elongatus, Leporinus macrocephalus, Prochilodus lineatus, Salminus brasiliensis, Pimelodus maculatus, Pinirampus pirinampu, Pseudoplatystoma corruscans, Pterodoras granulosus, and Rhaphiodon vulpinus were sampled in the Canal da Piracema, a fish passage system at Itaipu Dam, Paraná River. The migratory species were analyzed through 22 morphometric measurements and fineness ratio to identify morphological patterns related to swimming performance. Four species groups were indicated by the Cluster analysis: I) R. vulpinus; II) P. corruscans; III) L. macrocephalus, L. elongatus, P. lineatus, P. maculatus, and S. brasiliensis - measurements of head height and anal fin length formed this group; and IV) P. granulosus and P. pirinampu - measurements of maximum body width and caudal peduncle width contributed to form this group. The morphometric variables that most contributed to the distinction were head length and mouth width for groups I and II. The species R. vulpinus and P. granulosus differed from other species, showing fineness ratios of 9.4 and 3.7, respectively. Leporinus elongatus, L. macrocephalus, P. lineatus, P. maculatus, and S. brasiliensis showed significant differences from other species, with ratios ranging from 4.57 to 5.19, indicating that these species may be better swimmers. Long-distance migratory species using the Piracema Canal to ascend upstream areas differed morphologically, morphological characteristics such as a narrow caudal peduncle and maximum body length, besides to the values of the fineness ratio, were essential to differentiate the migratory species. Este estudo caracterizou as diferenças morfológicas entre espécies de peixes migradores da bacia do rio Paraná. Um total de 117 peixes adultos das espécies Leporinus elongatus, Leporinus macrocephalus, Prochilodus lineatus, Salminus brasiliensis, Pimelodus maculatus, Pinirampus pirinampu, Pseudoplatystoma corruscans, Pterodoras granulosus e Rhaphiodon vulpinus foram capturados no Canal da Piracema, um sistema de transposição para peixes na barragem de Itaipu, rio Paraná. As espécies migradoras foram analisadas através de 22 medidas morfométricas e razão fineza para identificar padrões morfológicos relacionados à capacidade natatória. Quatro grupos de espécies foram evidenciados pela Análise de Cluster: I) R. vulpinus; II) P. corruscans; III) L. macrocephalus, L. elongatus, P. lineatus, P. maculatus e S. brasiliensis, medidas de altura de cabeça e comprimento da nadadeira anal formaram este grupo; e IV) P. granulosus e P. pirinampu - medidas de largura máxima do corpo e largura do pedúnculo caudal contribuíram para a formação deste grupo. As variáveis morfométricas que mais contribuíram para distinção dos grupos I e II foram comprimento da cabeça e largura da boca. As espécies R. vulpinus e P. granulosus diferiram das demais, apresentando razão de fineza de 9,4 e 3,7, respectivamente. Leporinus elongatus, L. macrocephalus, P. lineatus, P. maculatus, S. brasiliensis diferiram significativamente das demais espécies com valores de razão fineza que variaram entre 4,57 a 5,19, indicando que estas espécies podem apresentar melhor desempenho natatório. As espécies migradoras de longa distância que utilizam o Canal da Piracema para ascender áreas a montante diferiram morfologicamente, características morfológicas como pedúnculo caudal estreito e largura máxima do corpo, bem como os valores de razão de fineza foram determinantes na diferenciação das espécies aqui analisadas.

The composition of the diets of 66 species of fishes was investigated from September 2009 to June 2010 in three subsystems of the Upper Paraná River floodplain (Brazil), following invasion by the two mollusk species Limnoperna fortunei (Dunker, 1857) and Corbicula fluminea (Müller, 1774), and the macrophyte Hydrilla verticillata (L.f.) Royle. Limnoperna fortunei was consumed in all three subsystems and occurred in the diet of 15 fish species, with a high proportion in the diet of Leporinus obtusidens. Corbicula flumineawas present in the diet of Pterodoras granulosus caught in the Paraná and Ivinheima subsystems. Hydrilla verticillataoccurred in the diet of Schizodon nasutus caught in the Ivinheima and Paraná subsystems. It is not yet possible to evaluate the potential of these species to control invasive mollusks in the study area or the impact of these species on the structure of the food chain. Omnivorous and herbivorous fishes in the study area may have little impact on the population of H. verticillata.

The presence of intact seeds in the digestive tract of fish could be a favourable indication for the occurrence of dispersal (Gottsberger 1978). The presence may be merely incidental or there may be a regular and natural link between fish and riverine plants, especially in areas subject to regular floods. The fish might act as carriers of diaspores upriver (Pijl 1982). The study of the behaviour of Pterodoras granulosus (Valenciennes 1883) has shown that this is an omnivorous migrating species. From March to July there is little migrating intensity and when it happens, it is downstream. August marks the start of upstream migration, probably towards the reproduction areas. The movement gathers intensity in October and reaches its peak in January (Fundacao Universidade Estadual de Maringa 1990). This kind of behaviour, according to Gottsberger (1978), would reinforce its position as a potential disperser. During the periods of flooding, the overflow considerably increases plant food available for the fish, while in the periods of drought it is reduced to the river banks. Similarly, the area of dispersal is also affected by the flow regime of the Parana River. Therefore, during flooding, the plant species, whose seeds go

In the present paper the authors describe and illustrate a new species of proteocephalidean cestode, Monticellia belavistensis, sp.n., parasite of a freshwater siluriform fish (thorny catfish). Pterodoras granulosus (Valenciennes, 1833), from the Itaipu Reservoir and Paraná River, in the region of Porto Rico. This is the first reference of a proteocephalid in this host. The values of prevalence and mean intensity of infection are given and the life cycle is discussed.

A new nematode genus and species. Neoparaseuratum travassosi n. g., n. sp., is described from the intestine of the freshwater thorny catfish, Pterodoras granulosus (Valenciennes), from the Paraná River, Brazil. This seuratoid nematode species represents a new genus of the family Quimperiidae, being characterized mainly by the presence of numerous narrow longitudinal bands of inflated cuticle extending along the cephalic region of the body, small deirids, postoesophageal position of the excretory pore, relatively short (0.159-0.303 mm), equal spicules and a gubernaculum, the absence of caudal alae and preanal sucker in the male, and by some other features.

The diet and feeding habits of armado catfish, Pterodoras granulosus (Valenciennes, 1821), were studied in the Lajeado Reservoir, Tocantins, Brazil, and the mouth of its tributaries. Stomach contents of 327 specimens were analyzed by the percentage composition and volumetric methods. The feeding of armado on a wide variety of foods, including both animal and plant items, leads to its classification as a euriphagic species with herbivorous tendency. However, it should be noted that armado showed a strong ontogenetic diet shift, with the gradual replacement of detritus and sediment by plant items, especially terrestrial ones. The environmental use pattern of P. granulosus corroborates the ontogenetic shift observed in its diet. Small fish predominated mainly in the benthic region and detritus and sediment represented an important resource, whereas large fish fed mainly on terrestrial plants, as they explore open water sites and the surface of the water column. Foi investigada a dieta e o hábito alimentar do armado, Pterodoras granulosus (Valenciennes, 1821) no reservatório do Lajeado, Tocantins e na foz de seus tributários. Conteúdos estomacais de 327 exemplares foram analisados através dos métodos de composição percentual e volumétrico. A utilização de uma ampla variedade de tipos de itens alimentares pelo armado, incluindo itens de origem animal e vegetal permite classificar esta espécie como eurifágica, com tendência à herbivoria. No entanto, deve ser considerado que esta espécie apresenta uma forte variação ontogenética na dieta. Foi constatada uma redução gradual na participação de detrito e sedimento na dieta em detrimento dos itens de origem vegetal, especialmente os terrestres. O padrão de utilização do ambiente por P. granulosus está de acordo com a variação ontogenética observada na dieta do armado. Enquanto os indivíduos pequenos utilizam predominantemente a região bentônica e têm o detrito e sedimento como itens importantes na composição da dieta os indivíduos de maior porte utilizam áreas abertas e superficiais da coluna da água tendo os vegetais terrestres como principal item da dieta.

Variations in the diet of Pterodoras granulosus (Osteichthyes, Doradidae) were evaluated from 1994 to 1998 taking into account two events that affected the abundance of an introduced bivalve Corbicula fluminae: (i) the abundance explosion of the bivalve in the reservoir, started in 1994 and (ii) the slaughter of the bivalve population due to fluctuations in water level, started in July 1996. Stomach contents were analyzed and results were shown considering the methods of frequency of occurrence and volumetric, combined in an alimentary index (AI). In 1994, 1995 and 1996 C. fluminae was the most consumed item, constituting about 90% of the diet. A decrease of this item intake (39%) was verified in 1997, with an increase of the vascular plants intake (26%). The diet of P. granulosus changed drastically in 1998, when it became based on algae (49%) and vascular plants (45). These results indicate the important role played by water level fluctuations in reservoirs, on the food availability for P. granulosus. Foram avaliadas as alterações na dieta de Pterodoras granulosus (Osteichthyes, Doradidae), no reservatório de Itaipu, no período de 1994 a 1998, associadas às alterações na abundância de um bivalve invasor, Corbicula fluminea, considerando-se dois eventos: (i) a explosão de C. fluminea no reservatório a partir de 1994, e (ii) a mortandade desse bivalvia em função das flutuações do nível de água a partir de julho/96. Os conteúdos estomacais, foram analisados pelos métodos de ocorrência e volumétrico, combinados no Índice Alimentar. A análise mostrou que C. fluminea foi o principal alimento nos anos de 94/95/96, representando aproximadamente 90% da dieta. Em 1997, houve uma queda no consumo de C. fluminea (39% da dieta), concomitante a um incremento no consumo de vegetal (26%), enquanto no ano de 98 a dieta foi composta basicamente por algas filamentosas (49%) e vegetal superior (45). Estes resultados evidenciam a importância da flutuação do nível da água em reservatórios sobre a disponibilidade alimentar de P. granulosus.

Aiming to evaluate the effect of parasitic load of Rondonia rondoni over the condition factor of Pterodoras granulosus. Fifty one specimens of P. granulosus were collected in Paraná River, (Porto Rico/Paraná). To analyze were used: Student’s “t”, to determine if length of hosts males and females were similar; Mann-Whitney test “U”, to determine the effect of sex of host on the intensity of infestion of the parasite; “G” Log-likelihood test, to determine the effect of sex of the host on the prevalence of parasite; coefficient of correlation “r”, to determine the correlation between the length of host and the prevalence of infection; Spearman rank correlation coefficient “rs”, to determine as possible correlation’s between the intensity of infection and the parasitic diversity with the length of the host, and to examine the correlation between the parasitic intensity and the condition factor (K). Based in this results we conclude, that despite of variations in the length, between males and females, the sex does not influence in the intensity and prevalence of infection. However, the intensity of parasites and the prevalence of R. rondoni increased with the length of host being that, the intensity does not affect the condition factor of Pterodoras granulosus, which mean to be in equilibrium with the parasite in this local Objetiva-se avaliar o efeito da carga parasitária de Rondonia rondoni sobre o fator de condição de armados, Pterodoras granulosus. Foram necropsiados 51 espécimes de armados, coletados no rio Paraná (Porto Rico/Paraná). Para as análises, utilizaram-se os testes de “t”, de Student, para determinar se o comprimento dos hospedeiros machos e fêmeas eram semelhantes; “U”, de Mann-Whitney, para determinar o efeito do sexo do hospedeiro na intensidade de infecção da espécie de parasito; “G” Log-likelihood, para determinar o efeito do sexo do hospedeiro na prevalência do parasito; coeficiente de correlação (CC) “r”, para determinar a correlação entre o comprimento do hospedeiro e a prevalência de infecção; CC por postos de Spearman “rs”, para determinar as possíveis correlações entre a intensidade de infecção e a diversidade parasitária com o comprimento do hospedeiro e para verificar a correlação entre a intensidade parasitária e o fator de condição (K). Os resultados permitiram concluir que, apesar das variações no comprimento entre machos e fêmeas, o sexo não influencia na intensidade e na prevalência de infecção. Porém a intensidade de parasitismo e a prevalência aumentaram com o incremento do comprimento do hospedeiro, e a intensidade parece não afetar o fator de condição de armado, o qual parece estar em equilíbrio com esse parasita nesse ambiente

A total of 1033 individuals of Pterodoras granulosus (512 males and 521 females) were collected in Itaipu Reservoir. Individual age was estimated through the rings found in the vertebrae. In the period studied, the highest number of rings found was 10 for both sexes. The rings are annual and formed in November, as observed in time variation analysis of marginal increment, possibly resulted from the reproductive period beginning. The growth curve, expressed through Von Bertalanffy model, using the nonlinear procedure, is: Ls=48,57[1-e-0,16(t+1,83)] for males and Ls= 65,06[1-e-0,11(t+1,87)] for females, in which the standard length is given in centimeters and the age in years Foram utilizados 1033 exemplares de Pterodoras granulosus (Siluriformes, Doradidae), 512 machos e 521 fêmeas coletados no reservatório de Itaipu, Estado do Paraná. A idade individual foi estimada a partir dos anéis etários encontrados nas vértebras. O número máximo de anéis encontrados nas vértebras para o período estudado foi 10 para ambos os sexos. Os anéis encontrados nas vértebras são anuais e formados em novembro, como o observado através da análise da variação temporal do incremento marginal médio, possivelmente resultado do início do período reprodutivo. A curva de crescimento expressa pelo modelo de von Bertalanffly, usando o procedimento não-linear, é Ls =48,57 [1-e-0,16(t+1,83)] para machos; e Ls = 65,06 [1-e-0,11(t+1,87)] para fêmeas, na qual o comprimento padrão é dado em centímetro e a idade em anos

In the present paper the authors describe and illustrate a new species of proteocephalidean cestode, Monticellia belavistensis, sp.n., parasite of a freshwater siluriform fish (thorny catfish). Pterodoras granulosus (Valenciennes, 1833), from the Itaipu Reservoir and Paraná River, in the region of Porto Rico. This is the first reference of a proteocephalid in this host. The values of prevalence and mean intensity of infection are given and the life cycle is discussed.

The blood of the fish of the rivers and swamps of British Guiana is not all equally affected by CO2. A regular series can be shown to exist between the paku (Myleus setiger Müll and Troschel), an active river fish whose blood is considerably affected, and the electric eel (Electrophorus electricus (L.)), which is an air-breather, frequenting relatively stagnant and poorly oxygenated water, and whose blood is almost independent of the presence of CO2. The blood of all the fish examined was found to be acid, generally about pH 6·7. The CO2 combining power of the blood of the fish examined was found to be very much lower than in other animals, but higher than might be expected on theoretical grounds. The possibility of another type of buffering is suggested. In the one fish examined (the bom-bom, Pterodorasgranulosus (Vai.)) the CO2 contained in reduced blood was found to be no higher than in oxygenated blood. In spite of the low oxygen content of some of the waters, no fish examined showed a haemoglobin with any markedly increased affinity for oxygen, such as might enable it to be saturated more easily at low pressures. The yarrow (Erythrinus erythrinus (Schn.) or Hoplerythrinus unitaeniatus (Spix.)) was found to be a fish which could either use its gills or take in bubbles of air into its air-bladder as a means of respiration. This fish has been studied in detail and the conditions controlling its respiration are described. Three factors are concerned, pH, oxygen content of the water, and CO2 content of the water. Of the three the last is most often the limiting factor. Carbonic anhydrase was found in the blood of all the fish examined for its presence, which include practically all those mentioned in this paper. The bearing of these results on certain problems of general biological interest is discussed.

A preliminary study on the application of radio-telemetry techniques to describe the movements of fish in a bypass channel at Itaipu Dam (Paraná River), known as "Canal da Piracema," was carried out between January and February of 2004. Fourteen individuals of six species (Prochilodus lineatus, Leporinus friderici, Schizodon borellii, Pseudoplatystoma fasciatum, Pterodoras granulosus and Cichla kelberi) were intragastrically and surgically radiotagged and monitored by three experimental fixed radio-telemetry stations installed in the upper portion of the Canal. The surgical implantation of transmitters and the anesthesia using clove oil proved to be more efficient and allowed easier handling in comparison to intragastric implantation and electronarcosis immobilization. The use of fixed stations to obtain data was found to be very suitable for tracking movements of several different fish species in the Itaipu lateral channel. Three species (P. granulosus, S. borellii and C. kelberi) moved downstream after release. Two individuals of P. fasciatum and two of P. lineatus migrated upstream, leaving the channel 7 and 10 days and 2 and 24 days after release, respectively. Leporinus friderici was the only species that did not leave the release site until the end of the study period. Um estudo preliminar sobre a aplicação de técnicas de radiotelemetria para descrever os movimentos de peixes no canal de transposição da UHE Itaipu (Rio Paraná), conhecido como "Canal da Piracema", foi realizado entre janeiro e fevereiro de 2004. Seis espécies (Prochilodus lineatus, Leporinus friderici, Schizodon borellii, Pseudoplatystoma fasciatum, Pterodoras granulosus e Cichla kelberi) totalizando 14 indivíduos foram marcadas com radiotransmissores via cirúrgica e esofágica e rastreados através de três estações fixas experimentais de radiotelemetria instaladas na porção superior do Canal. A implantação de transmissores através de cirurgia e a anestesia por óleo de cravo mostraram-se mais eficientes e de fácil manejo do que a imobilização por eletronarcose e a implantação intragástrica. A utilização de estações fixas para obtenção dos dados mostrou-se apropriada para rastrear os movimentos de diferentes espécies no canal de transposição de Itaipu. Três espécies (P. granulosus, S. borellii e C. kelberi) movimentaram-se para jusante após a soltura. Dois indivíduos de P. fasciatum e dois de P. lineatus migraram para montante, deixando o canal 7 e 10 dias e 2 e 24 dias após a soltura, respectivamente. Leporinus friderici foi a única espécie que não deixou o local de soltura até o final do estudo.

Sampling sites were located at: 1) a coastal area on Buenos Aires harbour where high concentrations of "sábalo" occur year round and which on account of its importance merits a specific program itself; 2) a coastal fringe from Buenos Aires harbour to Quilmes (34° 10' - 58° 10') and 3) different stations within the inner zone of the river, which were covered through a tagging campaign performed as part of an agreement among INIDEP-Argentina, CARP-Argentina, Uruguay, INAPE-Uruguay. At present (Winter 1989) recaptures from the first seven species have been obtained, with a total recovery of 3.81 o/o the highest percentages corresponding to patí, boga, armado and sábalo. (Document contains 25 pages.)