Comparative cytogenetic studies of Curimatidae (Pisces, Characiformes) from the middle Paraná River (Argentina)

Almost all species of the Curimatidae family have a stable karyotype, with a diploid number of 54 metacentric (M) and submetacentric (SM) chromosomes, and one sole nucleolus organizer pair. This family has considerable specific diversity in Argentinean fluvial basins; however, no cytogenetic data are available. Eight species from the Paraná River (Argentina): Cyphocharax voga, C. spilotus, C. platanus, Steindachnerina brevipinna, S. conspersa, Curimatella dorsalis, Psectrogaster curviventris, and Potamorhina squamoralevis were analyzed cytogenetically. Chromosome preparations were obtained from direct samples and through cell culture, and they were processed for conventional, C- and nucleolar organizer region-banding. Six of the species exhibited the standard family karyotype, with 2n = 54 M-SM and fundamental number of chromosomes (FN) = 108, as well as variations in the chromosome formula, and in heterochromatic and nucleolar organizer regions. Though nucleolar organizer regions were located on only one chromosome pair, they varied in both carrier chromosomes and pairs involved. On the other hand, C. platanus showed a complement of 2n = 58 M-SM and subtelocentric with FN = 116, and P. squamoralevis presented 2n = 102, with some M-SM and a large number of acrocentric chromosomes. Even though the karyotype macrostructure appears to be conserved, the speciation process within the family has been accompanied by micro-structural rearrangements, as evidenced by pattern diversity in the heterochromatin and nucleolar organizer regions. Some changes in chromosome macrostructure have also occurred in this group, primarily in C. platanus and P. squamoralevis, in which there have been centric dissociations and inversions.     

Brumptomyia angelae, a new species of Phlebotominae (Diptera, Psychodidae) of the Atlantic forest of the state of Paraná, Brazil

The male of Brumptomyia angelae, sp. nov., a new species of Phlebotominae (Diptera, Psychodidae) of the Atlantic forest of the state of Paraná, Brazil, is described and illustrated. This new taxon is closely related to Brumptomyia ortizi Martins, Silva & Falc?o 1971, Brumptomyia nitzulescui (Costa Lima, 1932), and Brumptomyia troglodytes (Lutz, 1922). The male genitalia of these three latter species have also been drawn.     

A new species of Curimata (Characiformes,Curimatidae) from Paraná system,in resistencia,Argentine

A new curimatid fish, Curimata gnaca, from two localities, both in the neighborhoods of Resistencia, Chaco Province, Argentine, is described. The species is distinguished from other curimatids by the position of the mouth, a low number of perforated scales in lateral line, scales with straight margin on sides of body and long pectoral fins. The new species is placed in the genus Curimata until the problems within it will be solved.     

Argyrotaenia sphaleropa (Meyrick) (Lepidoptera: Tortricidae) in citrus in the State of Paraná, Brazil

Argyrotaenia sphaleropa (Meyrick) is associated with various fruit species in South America. This tortricid was first detected in citrus, Citrus sinensis (L.) Osbeck, in Brazil, in commercial groves in northern Paraná, during the 1994/95-crop season. The aim of this work was to study the biology of this lepidopteran under laboratory conditions (28 +/- 2 degrees C, 70 +/-10% UR, 14h photofase) using the citrus cultivar Pêra. Larvae obtained from egg masses collected in a commercial citrus grove in Rolandia, PR, were individually placed on citrus terminal leaves inside glass shell vials (8.5 x 2.5 cm) until adulthood. A male and a female moth were then transferred to acrylic cages (13 x 10 cm) containing inside a bouquet made with new citrus flush to serve as oviposition substrate. Adults were fed daily with a 10% honey solution. The biological parameters evaluated were duration of development of egg, larval and pupal stages; pupae weight; duration of pre-oviposition and oviposition periods, fecundity and longevity. The length of the egg to adult stage was around 36 days. The pre-oviposition period was almost two days, the oviposition period approximately ten days and the embryonary period around six days. Adult longevity was almost 15 days for females and nine days for males, and the lifetime fecundity was slightly over 180 eggs.     

Populations and production of fish in two small tributaries of the Paraná River,Paraná, Brazil

Mean biomass (153-1) and production (P) of fish in two small tributaries of the Paraná River (Paraná, Brazil) were 61 kg ha^–1 and 48 kg ha^–1 yr^–1 in the Caracu River and 29 kg ha^–1 and 26 kg ha^–1 yr^–1 in the Agua do Rancho River, respectively. Matrix correlation analysis revealed high positive correlations of both 153-2 and P to maximum depth and hiding places and, at a lower level of significance, to mean depth, pH and oxygen level. Lower 153-3 and P values were found in the Agua do Rancho River, whose valley has retained a more natural character, rich canopy and scarcity of macrophytes, but also lower conductivity and nitrogen and phosphate levels than those in the Caracu River.Address for correspondence     

A new species of Kritskyia (Dactylogyridae,Ancyrocephalinae) parasite of urinary bladder of Prochilodus lineatus (Prochilodontidae,Characiformes) from the Floodplain of the High Paraná river,Brazil

A new species of Kritskyia inhabits the urinary bladder of the "curimba", Prochilodus lineatus in the floodplain of the high Paraná river. The new species resembles others members of Kritskyia in the following features: haptor lacking anchors and with 14 hooks marginal, posterior male copulatory organ non articulated with the accessory piece and vagina a sclerotized tube. However, it differs from the known species mainly by the shape of the copulatory complex. This is the third endoparasitic monogenean species reported from freshwater Neotropical fish.     

Influence of host sex and age on infracommunities of metazoan parasites of Prochilodus lineatus (Valenciennes, 1836) (Prochilodontidae) of the upper Paraná River floodplain, Brazil

149 specimens of Prochilodus lineatus were collected on the upper Paran6 River floodplain. Of these, 121 (82.1%) were parasitized. 33 species of metazoan parasites were recorded. Rhinonastes pseudocapsaloideum was classified as secondary, while all other species were classified as satellites. Ergasilus sp. and Tereancistrum curimba were positively associated and their abundances were positively correlated. Saccocoelioides magnorchis and S. nanii were positively associated and their abundances were positively correlated. The mean diversity in the infracommunities of P. lineatus was H = 0.6875 +/- 0.4398. Host standard length was not correlated with parasite diversity (rs = 0.1726; p = 0.0533). The abundances of T. curimba and Kritskyia boegeri, and S. magnorchis and S. nanii were significantly correlated with host length. Correlation between fish age and parasite prevalence was not significant. The abundances of Amplexibranchius sp., K. boegeri and S. magnorchis were significantly different among host age classes. For Amplexibranchius sp., the three-year old age class had more parasites. For K. boegeri, the intermediate age classes had the most numerous parasites. Only Tereancistrum curimba showed significant difference in the prevalence between the sexes, with females being more parasitized.     

Feeding ecology of Macrobrachium borelli (Nobili) (Decapoda: Palaemonidae) in the flood valley of the River Paraná, Argentina

The feeding habits and selectivity of Macrobrachium borelliiwere studied by examining the stomach content of specimens from anox-bow lake across one year. M. borellii isomnivorous-carnivorous, feeding largely on members oflittoral-benthic communities. The bulk of the stomach content wasformed by oligochaetes, dipteran larvae, and a variety of organismsranging from algae to palaemonids. Copepods and cladocerans were analternative food source in winter, at low-water, when macrophytes haddeclined. Oligochaetes and dipteran larvae were positively, algae andmicrocrustaceans negatively selected. This revised version was published online in July 2006 with corrections to the Cover Date.     

Population dynamics of Corbicula fluminea (Bivalvia) in the Paraná River Delta (Argentina)

Benthic individuals and drifting planktonic juveniles of Corbicula fluminea were sampled in the Lower Delta of the Paraná River (Argentina) at monthly intervals between October 1995 and October 1996. Densities of settled clams above 1 mm, around 300–1000 ind. m-2, varied little throughout the year. Below 1 mm benthic juveniles, on the other hand, showed a single conspicuous abundance peak in October-November (up to 1722 ind. m-2), and were practically absent during the rest of the year (overall annual mean: 1070 ± 797 ind. m-2). Drifting juveniles showed one major peak in December 1995 (160 ind. m^-3), and a minor one at the end of March (24 ind. m^-3). Length-frequency analyses of the monthly field data clearly indicate a highly structured population with a single well defined reproduction period centered on October–November. Population parameters derived from the seasonally oscillating version of von Bertalanffy's growth formula were as follows: maximum shell length: 32 mm (maximum observed shell length: 33 mm); growth constant: 0.65; growth seasonality (i.e., span of summer-to-winter growth-rate difference): 0.7; winter point (i.e., time of the year when growth is minimum): 0.5 (June–July); estimated size range for one year-old individuals: 15.3–22.4 mm; for two years: 23.5–27 mm, and three years: 27.5–29.3 mm. Comparison with previous data confirm the influence of water temperature on the clam's reproduction and growth and furnish additional evidence suggesting that food availability may be as important for recruitment as thermic regimes. Contrasts between traits of the population analyzed herein with those described previously from a nearby (ca. 10 km) site more influenced by industrial pollution point at the influence of water quality on Corbicula's recruitment and growth. This revised version was published online in July 2006 with corrections to the Cover Date.     

Leishmania (Viannia) braziliensis: epidemiology of canine cutaneous leishmaniasis in the State of Paraná (Brazil)

The present study examines the role that dogs play in the maintenance of the Leishmania cycle in the State of Paraná, Southern Brazil. Dogs were examined in three regions where cutaneous leishmaniasis is endemic or epidemic (R1-Vale da Ribeira; R2-Central region of Paraná State and R3-Northern region). To determine serum prevalence rates ELISA was used. In regions endemic for Trypanosoma cruzi (R1 and R3), serum from dogs seroreactive towards Leishmania antigen was subjected to T. cruzi adsorption in order to eliminate cross-reaction with common antigen epitopes. Concomitantly, dogs with cutaneous lesions were biopsied to isolate and identify parasites using RAPD. Leishmania were classified by the phenetic method using the Jaccard coefficient of similarity, and grouped by Unweighted Pair-Group Method using an Arithmetic Average (UPGMA). A total of 410 dogs were studied. In R1 (Vale da Ribeira) 159 dogs were evaluated of which 10 had anti-Leishmania antibody. In R2 (Central Paraná), 39 animals were examined of which 8 were seropositive. In R3 (the North) 212 dogs were evaluated of which 39 animals were seropositive. Thirteen dogs had cutaneous lesions and the parasites were isolated from a dog with mucocutaneous lesion in R1, two animals with simple skin lesions in R2 and 10 dogs with multiple lesions in R3. The identification of the parasite by molecular methods showed it to be L. (Viannia) braziliensis. Based on this information, the role of domestic dogs in Leishmania infection of cutaneous leishmaniasis in Paraná is discussed.     

Allozyme comparison of two populations of Rineloricaria (Siluriformes, Loricariidae) from the Ivaí River, upper Paraná River basin, Brazil

Two allopatric morphotypes of the genus Rinelocaria were compared through the allozyme electrophoresis technique: one morphotype, R. pentamaculata, from the Keller River in the middle stretch of the Ivaí River basin and the other, R. aff. pentamaculata, from the São João River in the upper portion of the Ivaí River basin. The morphotype from the São João River was collected upstream from the São João waterfall, which is about 80 m deep. Twelve enzymatic systems (AAT, ADH, EST, GCDH, G3PDH, GPI, IDH, LDH, MDH, ME, PGM and SOD) were analyzed, which allowed to score 22 loci. Only lociAat-2, Est-3 and Mdh-C showed polymorphism. The two samples differed in allele frequencies at the three polymorphic loci. The average expected heterozygosity for all loci was 0.0806 ± 0.0447 in the Keller River sample. For the São João River morphotype, this value was 0.0489 ± 0.0350. Nei'' s genetic identity and distance between the two populations were respectively 0.9789 and 0.0213. Wright''s F_IS , F_IT and F_ST over all loci were estimated as 0.3121, 0.4021 and 0.1309, respectively. We consider that the two morphotypes represent species in statunascendi.     

A new species of Ilyocryptus (Crustacea: Anomopoda) from the River Paraná basin,Argentina

A new species of Ilyocryptus Sars from several localities in River Paraná basin, is described and figured. By the presence of a lateral process on the valves I. paranaensis n.sp. resembles I. cornutus Mordukhai-Boltovskoi & Chircova, but it shows several morphological differences in the shape and the armature of the postabdomen and in the antennal formula.     

Stomach Content of Juvenile and Adult Piranhas (Serrasalmus marginatus) in the Paraná Floodplains,Brazil

The piranha, Serrasalmus marginatus is an abundant fish in the floodplains of the upper ParanáÝ river. We studied the stomach content of juvenile and adult piranhas over a year and determined the food items. Fragments of fish were the main diet components with age-dependent differences. There was no seasonal variation in the prey. This piranha is basically a diurnal predator with some differences in daily periods of feeding activity between juveniles and adults.     

Seasonal dynamics of Callibaetis willineri (Ephemeroptera, Baetidae) associated with Eichhornia azurea (Pontedericeae) in Guaraná Lake of the Upper Paraná River, Brazil

The micro-anatomy of the cephalon is described in the troglobic asellotan isopod Craseriella anops from the Nohoch Nah Chich anchialine cave system in southeast Mexico. The cephalon is entirely covered by cuticular scales bordered by marginal spines. The anterior end of the cephalon is bordered by a carina that is wider medially. The isopod is eyeless. The distal seventh portion of the cephalon is characterized by the presence of two sutures and six setae. A suture is found on each side of the distal margin of the cephalon.Each suture is bordered by microtrichs. Two simple setae with a sensory hair, articulated on the base by a socket, are found one on each side of each of the sutures. Two additional setae, similar in shape and size, occur medially on the cephalon. A terminal pore is absent on the sensory hairs of all setae. These setae are suggested to be mechanoreceptors that provide directional sensitivity and enhance the sensibility of turbulent motion, viscosity and changes of hydrostatic pressure.     

Diversity and Abundance of the Planktonic Rotifers in Different Environments of the Upper Paraná River Floodplain (Paraná State – Mato Grosso do Sul State,Brazil)

This study proposes that diversity and abundance of rotifers show spatial and temporal variations in the Upper Paraná River floodplain due to heterogeneity of the environment and hydrological level fluctuations of the main river. The structure and dynamics of rotifer assemblages were investigated by samplings carried out during the rainy (February) and dry period (August) of the year 2000, in 36 environments (rivers, channels, backwaters, open and isolated floodplain lakes). The influence of phytoplankton biomass on rotifer diversity and abundance was also investigated. 104 taxa of rotifers were identified. The highest species richness was found in rivers and open floodplain lakes, the highest abundances in the isolated floodplain lakes, and the highest values of species diversity in the channels, especially during the rainy period. β₂-diversity values were higher in the channels, especially during the dry period. Flow differences and food availability were predominant factors influencing the structure and dynamics of the rotifer communities.     

The influence of water and sediment properties on the occurrence of Potamocaris Dussart, 1979 (Harpacticoida) in the upper Paraná River (Brazil)

In the main channel of the Upper Paraná River, four sampling sites were established according to the profile of the bottom. Samples were carried out monthly from July 1993 to February 1995 with a modified Petersen grab. Four species were found at four sites: Potamocaris bifida, P. bidens, P. bidentata and P. tridentata. Canonical correspondence analysis indicated differences in the preferred microhabitats of the Potamocaris species, mainly in regard to sand particle size in the main river channel. Bedform stability was the most important factor affecting the abundance of this community.     

Fish diversity and community structure in two small tributaries of the Paraná River,Paraná State,Brazil

In eleven sites on two small tributaries of the Paraná River (North-West Paraná State), 6.8 and 4.0 km in length, 1263 fish specimens of 28 taxons and 14 families were collected using electrofishing. Up to twelve years ago the catchments of the two rivers were covered by tropical jungle; this has now been replaced by pasture and arable fields. Mean diversity indices of Simpson and Shannon indices were close to 0.6, which would indicate that human impact affected fish populations although the river beds have retained their original shape, except cleared of riparian trees. Despite their close location (about 18 km), the two streams differed from each other in their fish faunal composition. The distinctive nature of the fish communities in the two streams was a result of: conductivity, pH, also hiding places, riparian vegetation, submerged macrophytes and depth and width of the rivers.     

The reproductive strategy of Leporinus friderici (Characiformes, Anostomidae) in the Paraná River basin: the effect of reservoirs

The reproductive strategy of a species depends upon the interaction between intrinsic and extrinsic factors. Examining the population of Leporinus friderici in two reservoirs of the Upper Paraná River basin in reference to first gonadal maturation and breeding season and sites, the present investigation tested whether the environment formed by damming promoted spatial and temporal changes in the reproductive strategy of this species. Analyses of sex ratios showed that females significantly predominated in Itaipu, while in Corumbá the sexes were about equal with a slight predominance of males. Size-associated sexual dimorphism was observed, that is females dominated the longer length categories, and males the shorter. The minimum size at which L. friderici initiated reproduction varied from year to year, and was larger in the periods soon after formation of both reservoirs. In Itaipu, stabilization between the maximum and minimum lengths at first maturation was also noted after year 6 following closure and continuing until year 15. In general, the breeding season lasted from October through April, although cyclic changes in the duration and intensity of this season were evident. Young individuals predominated during the entire study period in Corumbá. The formation of Itaipu Reservoir had a greater effect on the reproduction of L. friderici, where a gradual adaptation of the reproductive strategy of this species may possibly have been occurring. It is also possible that some of the characteristics of the Itaipu population will in the future be shown by the Corumbá population. It was concluded that reproductive strategies constitute ecological adaptations that are temporally and spatially altered and are fitted to resource availability and environmental pressure.     

Petunia guarapuavensis (Solanaceae): A new species from planalto of Paraná and Santa Catarina,Brazil

Petunia guarapuavensis, a new species fromplanalto (high plateau) of Paraná and Santa Catarina in Brazil, is described, and its morphological distinction from related species, features of the habitats, and geographical distribution are discussed.     

Effects of water level fluctuations on phytoplankton in a river-floodplain lake system (Paraná River,Argentina)

Several aspects of community organization wereanalyzed comparatively in a small side-arm of theParaná River (Correntoso) and a shallowfloodplain lake (El Tigre) (31° 41 S and60° 42 W), in relation to the hydrology of thesystem. Taxonomic and morphological composition inthe river differed from that in the lake: the riverhad lower species richness (151 vs 218),different contributions of some Classes to totalspecies number (higher Cyano-, Zygo- andDiatomophyceae vs higher Chlorophyceae), anddiffent proportions of nannoplanktonic algae (67.5%vs 80.7%) and netplanktonic filamentousspecies (18.2% vs 4.2%). Phytoplanktonbiomass, higher in the lake than in the river due tothe retention time, was mostly dominated bynannoplankton and netplankton. Loticphytoplankton was dominated by typical fluvialspecies of Diatomophyceae (R-strategists). Riverconditions seem to maintain a subclimacticcommunity, which was little impacted by the flushingof populations from floodplain lakes. Water levelwas the main factor controlling phytoplanktonbiomass, species diversity (H), evenness (E) andcommunity change rate () in the river. Inthe lake, phytoplankton had an autogenicsuccessional sequence during the isolation phase (C-to S-strategists) and other responses todisturbance, mainly during the flood(R-strategists). Frequent changes in phytoplanktoncomposition, biomass, H, E and , revealed aenvironmental instability in the lake, which may beexplained by interactions of external factors(hydrology and climatology) and those of internalorigin, such as nutrients and grazing.