Larissa Sbeghen Pelegrini

A total of 30 specimens of Mylossoma aureum and 30 of Mylossoma duriventre from the Middle Madeira River Basin were examined between October 2020 to March 2021. Eight species of parasites were identified. About 65% of the hosts were parasitized. A total of 386 parasites was collected in M. aureum and 436 in M. duriventre. Species accumulation curves in M. aureum did not reach the asymptote, while in M. duriventre the curves showed tendency to stabilization. Contracaecum sp. larvae was the only endoparasite found. Anacanthorus paraspathulatus was the dominant species in M. aureum. In M. duriventre, the core species with highest parasite indexes was Mymarothecium sp. 3. Margalef’s and Shannon’s diversity indexes were higher in M. aureum. Most of the parasites showed an aggregated distribution pattern. Mymarothecium sp. 1, Mymarothecium sp. 2 and the parasite richness showed a significant positive correlation between its abundance and host length and between Mymarothecium sp. 1 abundance and host weight in M. aureum. All parasites are the first records for the Southern Amazonas. Except A. paraspathulatus, all M. aureum parasites are mentioned for the first time in this host. The three morphotypes of Mymarothecium spp. are probably new species that are in the process of taxonomic description. O total de 30 espécimes de Mylossoma aureum e 30 de Mylossoma duriventre da Bacia do Médio Rio Madeira foi examinado entre outubro de 2020 e março de 2021. Oito espécies de parasitos foram identificadas, e 65% dos peixes analisados estavam parasitados. Foram coletados 386 parasitos em M. aureum e 436 em M. duriventre. As curvas de acumulação de espécies em M. aureum não atingiram a assíntota, enquanto em M. duriventre as curvas tenderam à estabilização. Contracaecum sp. foi o único endoparasito encontrado. Anacanthorus paraspathulatus foi central e dominante em M. aureum. Em M. duriventre, a espécie central com maiores índices parasitários foi Mymarothecium sp. 3. Os índices de Margalef e Shannon foram maiores em M. aureum. A maioria dos parasitos apresentou padrão de distribuição agregado. Mymarothecium sp. 1, Mymarothecium sp. 2 e a riqueza parasitária mostraram correlação positiva significativa entre sua abundância e o comprimento de M. aureum e entre abundância de Mymarothecium sp. 1 e peso de M. aureum. Todos os parasitos são primeiros registros para o sul do Amazonas. Exceto A. paraspathulatus, todos os parasitos de M. aureum são mencionados pela primeira vez nesse hospedeiro. Os três morfotipos de Mymarothecium spp. são espécies novas que estão em processo de descrição taxonômica.

Studies on the production of Pimelodidae catfish in the Amazon are generally carried out in large fishing centers. However, the data referring to small-scale fisheries have gaps that can represent a risk to the activity. This study evaluated the volume produced and the revenue obtained from migratory catfish of the Pimelodidae family of commercial interest landed in Humaitá, Amazonas, Brazil, from May 2018 to April 2019. Daily monitoring was carried out with the Z-31 Fishermens Colony through questionnaires to fishermen for each vessel docked. The total production was 6013.93kg, with 1,689 fish counted and 13 species. A total of 186 landings by 122 fishermen in 24 fishing sites characterized as rivers, lakes, and igarapés were evaluated. The average selling price was R$5.57/kg, and the highest volumes were obtained from July to September, mainly with gillnets, where the Surubim Pseudoplatystoma punticfer had the highest volume and revenue. Low productivity was verified in most localities, characterizing the fishing as artisanal. The lack of adequate conditions for storing and transporting fish, the local hydrological variations, and the presence of hydroelectric plants on the Madeira River are major factors limiting the fishing expansion in southern Amazonas.

Oncoceratiumn. gen. is proposed to accommodate Oncoceratium amphidactylumn. gen. n. sp. (Monogenoidea, Gyrodactylidae). Although the proposed genus is monotypic, the differences presented in the diagnosis clearly establish it as distinct from species from other genera, such as Gyrodactylus von Nordmann, 1832 and especially those that occur exclusively in the Neotropical region. The new genus is diagnosed by the presence of a bulbous male copulatory organ, with one row of spinelets of similar sizes and shapes, while the only spine usually found in the gyrodactylids is absent or not differentiated; a haptor with anchors presenting points folded outwards, and superficial and deep roots continuous and indistinguishable; the absence of a deep bar; and hooks in two bilateral clusters of eight hooks. Oncoceratium amphidactylumn. gen. n. sp. is described from the tamboata fish, Hoplosternum littorale (Hancock) (Callichthyidae), and is characterized by the presence of a pair of horn-shaped anchors with the point turned outwards, a superficial bar shield and absent deep bar, hooks disposed in bilateral lobes, and a MCO with no spine or with a row with large spinelets visible in place of the spine. In addition to the morphological features, distance analysis and Bayesian inference, based on 5.8s and partial ITS2, support placing the new species in a new genus, and not including it in a cluster of species of Gyrodactylus and near to Gyrodactyloides bychowskii Albova, 1948, Ieredactylus rivuli Schelkle et al., 2011 and Laminiscus gussevi (Bychowsky & Polyansky, 1953) Palsson & Beverely-Burton, 1983.

Here, we evaluate the relationships between the infestation rates of five monogenean parasites species with the dry and wet seasons, with the organic and inorganic parameters of the water of two rivers: the Jacaré-Pepira and Jacaré-Guaçú, and with the condition factors of its fish hosts: Serrasalmus maculatus and Astronotus crassipinnis, in the state of São Paulo, southeastern Brazil. Fish were collected between January and December 2017. Anacanthorus serrasalmi, Amphithecium speirocamarotum and Gussevia asota had higher abundance rates (Student’s t test, p ≤ 0.05) in the wet season. Gussevia asota had its abundance negatively correlated to nitrate in the Jacaré-Pepira River and with total nitrogen and potassium in the Jacaré-Guaçú River. Regarding the fish hosts condition factors, was observed a positive correlation with the abundances of G. asota in the Jacaré-Guaçú River, and with A. serrasalmi in the Jacaré-Pepira River. In general, wet season favored an increasing in the infestation rates of the monogeneans parasites in their host species, mainly in the river considered as the most polluted, the Jacaré-Guaçú River. Of the five parasites species analyzed in this study, only Gussevia astronoti and Rhinoxenus piranhus had no interaction with seasonality, river water variables, or fish host condition factors. On the other hand, G. asota had interactions both with water parameters (nitrate and total nitrogen) and with the hosts condition factors, which reflected in the abundance and intensity rates, showing itself as a species sensitive to changes in the environment and, therefore, that can be considered as a bioindicator organism.

Raphidascarid nematodes have been the focus of several studies, mainly due to the zoonotic potential of some species, even though the cases are underreported. Due to the difficulty in identifying their larvae, the use of diagnostic techniques involving morphological and molecular analyses has grown in the last 20 years. The present study had as objective the morphological and molecular characterization of the L3 larval types of Hysterothylacium collected in Pomatomus saltatrix and Pagrus pagrus from the Brazilian coast, close to the municipality of Santos, State of São Paulo. Twenty specimens of P. saltatrix were necropsied and Hysterothylacium type V (n = 257) and Hysterothylacium type X (n = 5) larvae were found. Five specimens of P. pagrus were necropsied and all were parasitized by Hysterothylacium type V larvae. The analyses showed a genetic proximity relationship between Hysterothylacium types V with other Hysterothylacium V and with H. deardorffoverstreetorum, although this is a species inquirenda. Haplotypes for Hysterothylacium type X found in the present study formed a monophyletic group with other Hysterothylacium X, H. amoyense, and H. zhoushanense. Through this study, new hosts and localities were registered for Hysterothylacium type V and Hysterothylacium type X.

We recorded the parasitic fauna of Hoplias malabaricus in a Neotropical River from southeastern Brazil, the Jacaré-Pepira River, in the Tietê-Batalha River Basin. The objective of this study was to inventory the composition of the parasitic fauna of H. malabaricus collected, through ecological and biodiversity approaches. A total of 30 specimens of H. malabaricus were collected in 2018 using fishing nets. Parasites were prevalent in 96.6% of the hosts, with 710 parasites specimens collected, divided into 22 species from 4 different taxa (i.e., Monogenea, Digenea, Nematoda, and Acanthocephala). This was the first survey about the parasitic fauna of H. malabaricus in this river, where three species are new records for this host (i.e., Gussevia sp. 1, Gussevia sp. 2, and Raphidascaris sp.). All species found are new records for the Jacaré-Pepira River, which together with all the data obtained in the study, collaborates to increase knowledge and understanding of the global fish parasite biodiversity.

A new species of Phanerothecium Kritsky & Thatcher, 1977 (Oogyrodactylidae Harris, 1983) is described from locariid fish from southeast Brazil. Phanerothecium macrosomum n. sp. (Oogyrodactylidae) is described from the body surface of Hypostomus regani (Ihering, 1905) (Loricariidae). It is characterized by an armed male copulatory organ containing spines of different size from proximal to distal extremity, short peduncle and robust haptor.

The Amazon is very important regarding the continental extractive fishing as it has the greatest diversity of freshwater fish in the world. Some factors can contribute to identify significant changes in fish production, such as characterization based on common names, and synonyms or classifications only at the genus level. This creates noise in different types of analyzes and mistakes in determining effective productions, as well as levels of exploitation for management. Thus, this study aims to demonstrate the variation in fish production over the years 2001 and 2013, using control data from the fishing colony "Dr. Renato Pereira Gonçalves Z-31" in the municipality of Humaitá, southern Amazonas. These data were analyzed by collaborators from the Laboratory of Ichthyology and Fisheries Management of the Madeira River Valley, at the Federal University of Amazonas. The fish landing monitoring allowed the determination of the species caught in the regional fishery and evaluated the effect of the hydrological level and the pre- and post-installation periods of the Santo Antônio and Jirau HPPs in Rondônia, on the total production. The data set showed the significant decrease in fish production between 2008 and 2013. Among the factors that explain the observed changes are the mistakes in determining the effective production due to the lack of criteria in the grouping of many species, the absence of regulations, such as the "Portaria IBAMA Nº 48" which was created only in 2007, in addition to the installation period of the HPPs on the Madeira River. It was also possible to verify the effect of seasonality through hydrological quotas on fish production, with the highest values observed in July, August and September of the years analyzed.

A total of 53 tamboatás, Hoplosternum littorale, from the Batalha River, São Paulo, southeastern Brazil, were examined between February 2014 to December 2016. Seventeen species of parasites were identified, and 961 specimens were collected . The richness of each community varied from one to seven species of parasites per fish. The metacercariae of Diplostomum lunaschiae showed higher prevalence and mean abundance, being the core species. Gyrodactylus sp. obtained a higher mean intensity value. Aporocotylidae gen. sp. showed a significant negative correlation between its abundance and the standard host weight and length, while Spiroxys sp. showed a significant negative correlation between its abundance and the host weight. Batalha River has importance as a maintainer of local biodiversity with a relevant contribution to the knowledge of freshwater biodiversity in the State of São Paulo. Gyrodactylidae gen. sp., A. mordax, Aporocotylidae gen. sp., D. lunaschiae, Diplostomidae gen. sp. 1, Contracaecum sp., D. renale, Porrocaecum sp., Pseudocapillaria sp. 1, Pseudocapillaria sp. 2, S. contortus, Oligobdella sp., and L. cyprinacea are parasites mentioned for the first time in H. littorale. Aporocotylidae gen. sp., Gyrodactylidae gen. sp., and Oligobdella sp. are new species in process of taxonomic description by the authors of the present study.

We analyzed the distribution and ecological relationships in the parasitic infracommunities of four species of the genus Hypostomus: Hypostomus regani, Hypostomus strigaticeps, Hypostomus hermanni, and Hypostomus ancistroides, collected in the Batalha River, State of São Paulo, Brazil. Twenty-four parasite taxa were identified among myxozoans, monogeneans, digeneans, nematodes, and hirudineans occurring in the gills, body surface, eyes, brain, and intestine. Monogeneans presented the highest species richness. The highest parasite prevalence was observed for ectoparasites in the Hypostomus spp. analyzed. Except for Phanerothecium sp., all parasites presented an aggregate pattern of distribution. In relation to parasitic diversity, H. regani presented higher mean values of diversity indexes, while H. hermanni presented higher values for the specific richness; equitability values were the same in all fish species analyzed. Infracommunities were most differentiated from one another (p < 0.05) between H. reganni and H. ancistroides. Standard length, body mass, and sex of Hypostomus spp. were significantly correlated (positively or negatively) with at least one parasite species. This study emphasizes the importance of the Batalha River as a source of local and regional biodiversity expanding the knowledge of ecological interactions between the parasite–host relationships of Siluriformes fish.