Parasite biodiversity of Leporinus piau Fowler, 1941 (Characiformes, Anostomidae) in a lentic ecosystem from the Salgado River basin, Caatinga Domain, Brazil

Leporinus piau is a freshwater fish belonging to the family Anostomidae, popularly known as "piau" in Brazil. This species has wide distribution in Brazilian northeast basins and presents an economic and sporting fishing importance. The present study aims to inventory the parasitofauna of L. piau of a freshwater ecosystem of Caatinga domain (Brazil). A total of 598 parasite specimens were recovered from nine parasitized hosts, belonging to four taxonomic groups: one Myxozoa (Henneguya sp.); four Monogenea (Dactylogyridae gen. sp., Jainus sp., Urocleidoides sp. 1 and Urocleidoides sp. 2); one Nematoda (Procamallanus (Spirocamallanus) inopinatus) and two Copepoda (Ergasilus sp. and Gamispatulus schizodontis). Previous studies reported five parasitic associations in L. piau: two nematodes (P. (S.) inopinatus and Procamallanus (Spirocamallanus) saofrancicencis) and three crustaceans (Argulus sp., Brasergasilus sp. and Ergasilus sp.). For the first time, this study records myxozoan and monogeneans parasitizing the host L. piau. The present study stands out the importance of the knowledge of the parasite biodiversity of freshwater fish in neotropics, reporting new occurrences and parasitic association for ichthyofauna of the Caatinga domain.

Diversity and community ecology of metazoan parasites in Tetragonopterus argenteus Cuvier, 1816 (Characiformes, Characidae) from Jaguaribe River basin in Brazil

The present study aims to inventory the metazoan parasites of Tetragonopterus argenteus from the Lima Campos weir, municipality of Icó, Ceará, Brazil and to analyze the influence of the host size and sex on the prevalence and parasitic abundance. A total of 359 metazoan parasites specimens were collected from 54 specimens of T. argenteus, presenting a mean intensity of 7.04 parasites/fish and prevalence of 94%. A richness of 10 parasite taxa were recorded, taxonomically classified into the following groups: Monogenea (n=1), Digenea (n=2) and Nematoda (n=7). The parasite community of T. argenteus was composed of helminth species with low prevalence, low mean intensity, low mean abundance, low dominance and low diversity, predominance of endoparasites of the phylum Nematoda. As for the importance value, six species were considered secondary and showed an aggregated dispersion pattern. The host size influenced significantly the abundance of Creptrotrema sp. and the prevalence of Procamallanus (Spirocamallanus) hilarii. The results present new reports of parasites have been recorded for this host, thus expanding the ecological interactions between parasites and Characiformes fish and contributing to the knowledge of the freshwater biodiversity from Brazilian Caatinga domain.

Characithecium spp. (Monogenea: Dactylogyridae) from Astyanax bimaculatus (Characiformes: Characidae) in Northeast Brazil, with Description of a New Species

PURPOSE

To date, seven species of Characithecium Mendonza-Franco, Reina and Torchin, 2009 (Monogenea, Dactylogyridae) are valid, parasitizing mainly fishes of the family Characidae (Characiformes) in the Neotropical region. During a parasitological study of fishes in the Batateiras River and Carás stream, Ceará state, Brazil, two species of Characithecium were collected from the gills of Astyanax bimaculatus Linnaeus, 1758 (Characidae). The purpose of the present study is to describe a new species of monogenean of the genus Characithecium and report Characithecium costaricensis Mendoza-Franco, Reina and Torchin, 2009 in A. bimaculatus, in Brazil.

METHODS

Monogeneans were isolated from the gills and stored in 70% ethanol, mounted in Gray and Wess' medium or and in a mixture of glycerin ammonium picrate (GAP) to study sclerotized structures. Morphological analyses were performed with a computerized image analysis system with differential interference contrast (DIC). The drawings were obtained with the aid of a camera lucida mounted on a Leica DMLS microscope.

RESULTS

Characithecium bifurcuprolatum n. sp. differs from its congenerics by the morphology of the accessory piece having a ventral unit articulated to cirrus base, a non-articulated dorsal and mid-ventral, and a sclerotized vaginal vestibule. Characithecium costaricensis was described from Astyanax aeneus (Günther, 1860) (Characidae) in Central America, and the present finding represents a new geographical and host records in Brazil. Furthermore, we observed the presence of a membrane at the base of the cirrus not mentioned in the original description.

CONCLUSION

Our findings increase to eight the number of known species of the genus Characithecium parasitizing characids in neotropics. We verified some additional characteristics present in the two species studied, such as the presence of a membrane at the base of the cirrus, an accessory piece with two subunits (an articulated ventral and a dorsal non-articulated) and the presence of sclerotized vaginal vestibule.

A new species of Wallinia Pearse, 1920 (Digenea: Allocreadiidae), in Astyanax bimaculatus (Linnaeus, 1758) (Characidae) in Northeast Brazil, based on morphology and DNA sequences

Wallinia caririensis n. sp. is described from the intestine of Astyanax bimaculatus (Linnaeus, 1758) (Characidae) collected in the Batateiras River in the municipality of Crato, Ceará state, Brazil. The description was based on integrative taxonomy approach using DNA sequences from the D1-D3 domains of the 28S rDNA gene. The new species was confirmed through the phylogenetic analysis of the 28S rDNA gene, which showed that Wallinia caririensis n. sp. is a sister taxon of Wallinia brasiliensis (Dias, Müller, Almeida, Silva, Azevedo, Pérez-Ponce de León, and Abdallah, 2018, and Wallinia anindoi Hernández-Mena, Pinacho-Pinacho, García-Varela, Mendonza-Garfias, and Pérez-Ponce de León, 2019), a species which parasitizes Astyanax fasciatus (Cuvier, 1819), A. lacustris (Lucena and Soares, 2016) in Brazil, and A. aeneus (Günther, 1860) in Mexico, with genetic divergences of 2% and 3%, respectively. The new species can be distinguished morphologically from its congeners by possessing large body size (length and width) and tapered extremity in the posterior end of the body, eyespots are present at the pharynx level, and vitelline follicles reach up to the half distance between the posterior testis and the extremity of the body, by having larger testes distributed in coincident zones (i.e., contiguous) and non-operculated eggs (a conspicuous characteristic in W. brasiliensis). To date, species of this genus have already been described in freshwater fishes from Mexico, Costa Rica, Venezuela, and Southeastern Brazil. The species described in this study consists of the second species parasitizing characids in Brazil, and the first record in Northeastern Brazil. This finding fills a gap and expands the biogeographic distribution of the genus Wallinia in South America.

How does host ecology influence sampling effort in parasite diversity estimates? A case study using Neotropical freshwater fishes

Accurately estimating biodiversity is fundamental to ecological understanding and prediction. Helminthes are often neglected in biodiversity estimates and when included are often underestimated. Here we examine how sampling effort affects estimates of parasite diversity in an assemblage of freshwater fish from a floodplain in Brazil. We also examine how ecological and behavioral factors influence the sampling effort necessary to accurately estimate the parasite diversity associated with a fish species. We use our dataset to suggest that host species with wide geographic distribution (i.e., long migrations), gregarious behavior (i.e., shoal), larger body size, higher population density, wide diet breadth (i.e., omnivorous), and autochthonous origin, increase the effort necessary to estimate the total diversity of parasites. However, estimating this parasitic fauna has several restrictions and limitations, due to the highly complex of the floodplain ecosystems, with non-linear and non-random responses.

Monogeneans (Dactylogyridae) parasitizing gills of Salminus hilarii from a Neotropical reservoir, Brazil

With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of São Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae)

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Novas ocorrências de metacercária de Austrodiplostomum compactum (Lutz, 1928) (Platyhelminthes: Digenea) parasito de olhos de peixes da Bacia do Rio Paraná

Austrodiplostomum compactum (Platyhelminthes: Digenea) parasita os olhos de várias de espécies de peixes. A presença deste parasito, em casos extremos, pode causar exoftalmia, deslocamento da retina, opacidade do cristalino e cegueira ou até a morte. O presente estudo registra novas ocorrências desta metacercária infectando os olhos de quatro novos hospedeiros de peixes, Serrasalmus maculatus coletado no reservatório de Rosana no rio Paranapanema e Hypostomus regani, Schizodon borellii e Auchenipterus osteomystax coletados na planície de inundação do alto rio Paraná.