Phylogeny of the Neotropical genus Acestrorhynchus (Ostariophysi: Characiformes) based on nuclear and mitochondrial gene sequences and morphology: A total evidence approach

Acestrorhynchus is the sole genus of the family Acestrorhynchidae which includes 14 species currently recognized as valid. Species of Acestrorhynchus comprise small-to-medium sized piscivorous fishes and have been traditionally grouped on the basis of well-defined color patterns. A recent phylogeny, based on morphological characters, could not resolve the phylogenetic affinities of A. heterolepis and the relationships among the species of the clade formed by A. abbreviatus, A. altus, A. falcatus, A. lacustris, and A. pantaneiro. The simultaneous analysis of two mitochondrial genes (16S and ATP synthase subunits 6 and 8) and one nuclear intron (S7) was able to resolve the latter clade, but the position of A. heterolepis remained unresolved. The combination of the molecular and morphological data sets in a total evidence analysis resulted in a well-resolved hypothesis regarding the phylogenetic relationships of Acestrorhynchus species. (C) 2009 Elsevier Inc. All rights reserved.

Diet and feeding activity of Acestrorhynchus lacustris (Lütken, 1875) (Characiformes, Acestrorhynchidae) in the water reservoir at Ribeirão Claro, SP

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytogenetic analysis of species of the genera Acestrorhynchus, Oligosarcus and Rhaphiodon (Teleostei: Characiformes)

In the present study the karyotypes and the number and position of nucleolus organizer regions (NORs) of four species of Characiformes are described. The analyses showed that Acestrorhynchus lacustris had 2n=50 chromosomes (8M+34SM+6ST+2A), Oligosarcus longirostris had 2n=50 chromosomes (2M+20SM+10ST+18A), Oligosarcus cf. paranensis from Keller and Mourão rivers had 2n=50 chromosomes (2M+26SM+8ST+14A), and Rhaphiodon vulpinus had 2n=54 chromosomes (32M+12SM+8ST+2A). The number of NOR-bearing chromosome pairs ranged from one to three among the species studied. The results available show that there is no variation in the diploid number within the genera analyzed. However, clear differences related to the karyotypic formulae and the number and position of Ag-NORs were found even in the comparison between populations. The possible relationships between the genera analyzed and other Characiformes are discussed.

Estrutura fina do espermatozóide de Acestrorhynchus falcatus Bloch (Teleostei, Characidae) da região norte do Brasil

Spermatozoa of amazon fish, Acestrorhynchus falcatus Bloch, 1794 were investigated by optical microscopy (DIC) and electron microscopy (TEM). Spermatozoa have no acrosome, the head is ovoid, and the midpiece region cylindrical, contains spherical mitochondria. The centriolar complex is located at the lateral side of the nucleus, formed by nine peripheral pairs of microtubules and arranged in a right angle to each other. The flagellum consists of nine pairs of peripheral and two central microtubules.

Estudo dos mixozoários (Myxozoa : Myxosporea) parasitos dos peixes characiformes Acestrorhynchus lacustris (Lütken, 1875) e Steindachnerina insculpta (Fernández-Yépez, 1948) coletados no Rio do Peixe, médio Rio Tietê, SP, Brasil

The São Paulo State has as one of its main rivers the Tietê, which is an extremely important source because of its biodiversity, use in navigation and mainly as direct supplier of water for thousands of people in the region. Currently, the biodiversity of marine and freshwater ecosystems has been threatened, primarily by environmental problems resulting from the degradation of ecosystems, an example is the stretch of the Middle Tietê River, where the Barra Bonita dam (SP) focused virtually the whole load organic effluents from the metropolitan region of São Paulo, leading to eutrophication with the loss of water quality. This basin is located in the Peixe’s River, a tributary of the Barra Bonita whose sources are on the slopes of the Cuesta de Botucatu, presenting an altitudinal gradient in a good state of conservation and water quality. From another perspective, the studies related to parasites and other pathogens of aquatic organisms have considerably increased the relevance, especially those hosts with potential for growing and marketing, given the significant increase these activities in Brazil and worldwide. Among the agents responsible for diseases in fish are the myxosporean, which can cause major economic damage, with high mortality ratios. Based on the above, this study evaluated the biodiversity of myxosporean parasites of two species of fish Acestrorhynchus lacustris and Steindachnerina insculpta. During the period January to November 2012, 40 specimens of Acestrorhynchus lacustris and 33 specimens of Steindachnerina insculpta were collected from the Peoxe’s river at four different points. The necropsies were performed and all organs were analyzed looking for myxosporean. Only the species Steindachnerina insculpta had their gills parasitized by two species of the genus Henneguya

Parasite communities of the predatory fish, Acestrorhynchus falcatus and Acestrorhynchus falcirostris, living in sympatry in Brazilian Amazon.

This study investigated the parasite communities of wild Acestrorhynchus falcatus and Acestrorhynchus falcirostris populations living in sympatry in Brazilian Amazon. In these two hosts, a total of 12 parasite species e 1-9 parasite species were found per fish, and 10 of these species are metazoans. Eight species of parasites were common to both host species and four of them exhibited differences in abundance and/or prevalence. Parasite communities of the hosts were taxonomically similar (83%) and composed of both ectoparasites and endoparasites, and characterized by high prevalence and high abundance of endoparasites and an aggregated dispersion pattern. For A. falcirostris, the dominant parasite was Ichthyophthirius multifiliis, and for A. falcatus, it was Piscinoodinium pillulare. Shannon diversity and Berger-Parker dominance were similar for both hosts, while the parasites species richness and evenness showed differences influenced by the ectoparasites species. These two populations of hosts that inhabited the same geographical area had different sizes, but were exposed to the same infective stages, and acquired qualitatively and quantitatively similar endoparasites community, thus indicating that the amounts and types of prey congeneric that they were eating were similar. Therefore, the overlap in the same occurrence area play an important role in the parasite communities to these phylogenetically related hosts.

Assessment of the ichthyofauna in stretches under the influence of Salto Grande Reservoir (Middle Paranapanema River, SP/PR, Brazil).

Aim: To analyze the composition, species richness and spatial distribution of the fish fauna in the area under influence of the Salto Grande Reservoir; Methods: Fish were caught every two months from November/05 to October/06, using gill nets, seining nets and sieve; Results: It was registered 67 fish species, 1,964 individuals and 146.2 kg, representing CPUEn of 1,964 and CPUEb of 278 kg. The most representative orders were Characiformes, with 29 species, Siluriformes (21 species) and Perciformes (11 species) Nine non-native species were registered. The most abundant species in the reservoir were Astyanax altiparanae, Steindachnerina insculpta and Acestrorhynchus lacustris, indicating the predominance of medium and small fishes in this reservoir. The dendrogram of similarity separated the Dam and Pedra Branca stretches from Pardo River Mouth, indicating differences in the assemblages. The species turnover among the stretches was demonstrated by the beta diversity, which may be related to the diversity of habitat; Conclusions: Although being a small reservoir, it displays great habitat diversity, reflecting in the composition and structure of fish assemblages.

NEW HOSTS and DISTRIBUTION RECORDS FOR NEMATODE PARASITES of FRESHWATER FISHES FROM São Paulo STATE, BRAZIL.

A study on the nematode parasites of nine species of freshwater fishes from Peixe River São Paulo, State, Brazil. was conducted. Fish were collected between February 2010 and March 2011 and the following species were found: Procamallanus (Spirocamallanus) inopinatus and Contracaecum sp. (larvae) in Astyanax altiparanae; Contracaecum sp. (larvae), Dioctophyma renale (larvae), Philometroides caudata, P. (Spirocamallanus) inopinatus, P. (Spirocamallanus) neocaballeroi (larvae) and P. (Spirocamallanus) saofranciscensis in Acestrorhynchus lacustris; Contracaecum sp. (larvae), Guyanema sp., Hysterothylacium sp. (larvae) and Icthyouris sp. in Cyphocharax modestus; Contracaecum sp. (larvae), Cosmoxynemoides aguirrei and Pharyngodonidae gen. sp. in C. nagelii; Dioctophyma renale (larvae), Hysterothylacium sp. (larvae) and Rhabdochona sp. in Gymnotus sylvius; Capillariidae gen. sp. in Hoplosternum littorale; Cosmoxynema vianai, Guyanema sp., Ichthyouris sp. and Travnema travnema in Steindachnerina insculpta; Contracaecum sp. (larvae), Procamallanus (Spirocamallanus) rebecae (larvae) in Triportheus angulatus and Rhabdochona acuminata in Triportheus nematurus. This is first study of nematode parasites from the Peixe River, therefore all the species found are new geographical records and 19 are new host records.

Nuclear DNA content determination in Characiformes fish (Teleostei, Ostariophysi) from the Neotropical region

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relações entre acúmulo de metais em tecido muscular de peixes com diferentes hábitos alimentares coletados na Bacia Hidrográfica do Turvo/Grande

Pós-graduação em Química - IBILCE

Partilha de recursos alimentares nas assembléias de peixes do reservatório de Salto Grande (médio rio Paranapanema SP/PR, Brasil)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aspectos da morfologia na relação presa/predadores de três predadores Characiformes e suas principais presas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Host-parasite interaction between crustaceans of six fish species from the Brazilian Amazon.

Host-parasite interactions between crustaceans and six fish species (Psectrogaster falcata, Ageneiosus ucayalensis, Acestrorhynchus falcirostris, Hemiodus unimaculatus, Serrasalmus gibbus and Geophagus proximus) from a reservoir in eastern Amazon, northern Brazil, were investigated. Eight hundred and seventy-eight parasites belonging to three crustacean species, Excorallana berbicensis, Argulus chicomendesi and Ergasilus turucuyus, which parasitized the hosts? mouth, gills and tegument, were collected from 295 fish and examined. High infestation levels were caused by E. berbicensis on the body surface of the hosts. Excorallana berbicensis showed aggregate dispersion, except in S. gibbus, while E. turucuyus showed random dispersion in A. falcirostris. The host?s sex did not influence infestation by E. berbicensis, and high parasitism failed to affect the body conditions of the fish. In the case of some hosts, rainfall rates, temperature, dissolved oxygen levels and water pH affected the prevalence and abundance of E. berbicensis, the dominant parasite species. Results revealed that the environment and life-style of the hosts were determining factors in infestations by parasites. Current assay is the first report on E. berbicensis for the six hosts, as well as on A. chicomendesi for G. proximus and P. falcata.