Parasite diversity in Oxydoras niger (Osteichthyes: Doradidae) from the basin of Solimões River, Amazonas state, Brazil, and the relationship between monogenoidean and condition factor

Dactylogyrids (Platyhelminthes, Monogenea) from the gill lamellae of doradids (Siluriformes) with description of five new species of Cosmetocleithrum and new geographical distribution for known species from the Neotropical Region, Brazil

Five new species of Cosmetocleithrum were described parasitizing the gill filaments of neotropical doradid fishes. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. and Cosmetocleithrum ludovicense n. sp. are described from Platydoras brachylecis from a market-place of São Luís, State of Maranhão, Brazil. Cosmetocleithrum sacciforme n. sp. and Cosmetocleithrum basicomplexum n. sp. are described from Oxydoras niger from Juruá River, State of Acre, Brazil. Cosmetocleithrum undulatum and Cosmetocleithrum brachylecis resemble Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 mainly by the unique male copulatory organ (MCO) morphology but differ from these and all congeneric species mainly by the morphology of the MCO, accessory piece and hooks pairs. Cosmetocleithrum ludovicense is closer to Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986 and to Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 but differs from those mainly by the morphology of the accessory piece. Cosmetocleithrum sacciforme differs from all congeneric species mainly by the morphology of the accessory piece formed by a single plate of saccular appearance. Cosmetocleithrum basicomplexum also shares morphological characters with Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 considering the size of the body and shape of the anchors, but differs mainly in the morphology of the bars and hooks. Besides the new species, new data are presented for Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018, C. akuanduba and C. confusus regarding morphological characteristics and biogeography.

Sphaerospora festivus n. sp., a parasite of the flag cichlid, Mesonauta festivus (Teleostei: Cichlidae) from eastern Amazon, Brazil

The present study describes a new species of the genus Sphaerospora found in the urinary bladder of the flag cichlid, Mesonauta festivus collected in Corre Água district of the municipality of Macapá, Amapá State (Brazil). The study includes morphological and phylogenetic analyses of the new parasite, to determine the relationship of the new species with related myxosporean species. The new species has polysporous plasmodia, which vary in size and shape. The mature myxospores are subspherical shape in valvar view. In the sutural view, the myxospores are 5.3±0.2 (5.2-5.6) μm in length and 7.0±0.7 (6.3-7.7) μm in width, with two piriform polar capsules equal size, 2.5±0.2 (2.3-2.8) μm in length and 1.8±0.2 (1.6-2.0) μm in width. The phylogenetic analyses of a partial sequence of the 18S rRNA gene confirmed the status of the new species and determined the relationship of the new species and related myxosporean species.The sum of the evidence indicates that, Sphaerospora festivus n. sp. belongs to the family Sphaerosporidae, and is the first record of the genus Sphaerospora from Brazil.

Dactylogyrids (Platyhelminthes: Monogenoidea) from the gills of Hassar gabiru and Hassar orestis (Siluriformes: Doradidae) from the Xingu Basin, Brazil

Four species ofCosmetocleithrum(three new) and one new species ofVancleaveusare described or reported parasitizing the gills of doradid catfishes (Siluriformes) from Xingu River and related tributaries:Cosmetocleithrumphryctophallussp. nov. andCosmetocleithrumbifurcumMendoza-Franco, Mendoza-Palmero & Scholz, 2016 fromHassarorestis;Cosmetocleithrumleandroisp. nov. fromHassargabiru;Cosmetocleithrumakuandubasp. nov. andVancleaveusklassenisp. nov. fromHassarorestisandH.gabiru.Cosmetocleithrumphryctophallussp. nov. differs from its congeners by possessing a male copulatory organ (MCO) with 2 ½ counterclockwise rings, and an accessory piece with an elongate torch-shaped blade.Cosmetocleithrumleandroisp. nov. has a MCO comprising a coil of about 3 ½ rings, a sigmoid accessory piece with a cup-shaped distal portion, a single type of hooks, and anchors with poorly differentiated roots.Cosmetocleithrumakuandubasp. nov. is characterized mainly by having a J-shaped MCO, an elongate accessory piece with sharp distal region, distal portion with a small gutter, and a heavily sclerotized vagina with short “S”-shaped vaginal canal.Vancleaveusklassenisp. nov. differs from the other species of the genus occurring in doradids by possessing anchors with triangular to subtriangular superficial root, developed deep root, and a coiled MCO with 2 ½ counterclockwise rings.Cosmetocleithrumbifurcumwas reported for the first time parasitizing doradids from Brazilian Amazon.

Ectoparasites community in Satanoperca jurupari (Cichlidae) from the Jari River, a tributary from Amazon River in Northern Brazil

The aim of this study was to investigate the gills parasites in Satanoperca jurupari from the Jari River, state of Amapá, in eastern Amazon (Brazil). The gills of 100% of the hosts were parasitized by Ichthyophthirius multifiliis (Protozoa), Sciadicleithrum juruparii (Monogenoidea) Genarchella genarchella, Posthodiplostomum sp. (Digenea) Ergasilus coatiarus and Argulus multicolor (Crustacea), and a total of 27,043 parasites were collected. However, the dominance was of I. multifiliis and there was aggregated dispersion of parasites with greater discrepancy for S. juruparii and A. multicolor. Low species richness of parasites (3.1 ± 1.1), low Brillouin diversity index (0.27 ± 0.23), low evenness (0.16 ± 0.13) and high dominance of Berger-Parker (0.88 ± 0.15) were found. The community of parasites in S. jurupari was characterized by low species richness, low diversity and low evenness, with high prevalence and low abundance. The size of host did not have any influence on the parasites community, but the host behavior and availability of infective stages of the parasites were factors structuring the community of ectoparasites found here.

Annotated checklist of fish cestodes from South America

An exhaustive literature search supplemented by a critical examination of records made it possible to present an annotated checklist of tapeworms (Cestoda) that, as adults or larvae (metacestodes), parasitize freshwater, brackish water and marine fishes, i.e. cartilaginous and bony fishes, in South America. The current knowledge of their species diversity, host associations and geographical distribution is reviewed. Taxonomic problems are discussed based on a critical evaluation of the literature and information on DNA sequences of individual taxa is provided to facilitate future taxonomic and phylogenetic studies. As expected, the current knowledge is quite uneven regarding the number of taxa and host-associations reported from the principal river basins and marine ecoregions. These differences may not only reflect the actual cestode richness but may also be due to the research effort that has been devoted to unravelling the diversity of these endoparasitic helminths in individual countries. A total of 297 valid species, 61 taxa identified to the generic level, in addition to unidentified cestodes, were recorded from 401 species of fish hosts. Among the recognized cestode orders, 13 have been recorded in South America, with the Onchoproteocephalidea displaying the highest species richness, representing c. 50% of all species diversity. The majority of records include teleost fish hosts (79%) that harbour larval and adult stages of cestodes, whereas stingrays (Myliobatiformes) exhibit the highest proportion of records (39%) among the elasmobranch hosts. Fish cestodes are ubiquitous in South America, being mostly recorded from the Warm Temperate Southeastern Pacific (WTSP; 31%) for marine hosts and the Amazon River basin (45%) for freshwater ones. The following problems were detected during the compilation of literary data: (i) unreliability of many records; (ii) poor taxonomic resolution, i.e. identification made only to the genus or even family level; (iii) doubtful host identification; and (iv) the absence of voucher specimens that would enable us to verify identification. It is thus strongly recommended to always deposit representative specimens in any type of studies, including faunal surveys and ecological studies. An analysis of the proportion of three basic types of studies, i.e. surveys, taxonomic and ecological papers, has shown a considerable increase of ecological studies over the last decade.

Morphological and molecular characterization of cucullanid nematodes including Cucullanus opisthoporus n. sp. in freshwater fish from the Brazilian Amazon

Molecular and morphological characterization of two species of Cucullanidae from freshwater fish in Brazil are provided, one of which represented an undescribed taxon. Cucullanus opisthoporus n. sp. was collected in Cichla melaniae from River Xingu, State of Pará, and in C. pinima from River Jamarí, State of Rondônia. Nematodes referable to Cucullanus grandistomis were collected in Oxydoras niger from River Xingu. The new species has an appendage in the tail tip, ventrally covered by small spines, which is an exclusive feature of Cucullanus tucunarensis. However, C. tucunarensis differs from C. opisthoporus n. sp. based upon the relative position of deirids and the excretory pore, which are more posterior from the oesophageal end in the new species. Observations of C. tucunarensis type specimens also revealed features that were wrongly or not reported in the original description. Type specimens of C. grandistomis were observed, although they were poorly preserved. After evaluation of newly collected specimens of C. grandistomis, features unreported in the original description were observed for the first time, including the presence of an intestinal caecum. Thus, C. grandistomis was transferred to Dichelyne. Sequences of the 18S and 28S rRNA genes revealed high genetic similarity between the specimens of C. opisthoporus n. sp. from the two different hosts as well as their genetic distance from Dichelyne grandistomis n. comb. Phylogenetic reconstructions using representatives of Cucullanidae suggested the artificiality of the current morphological system adopted to separate the genera, since most genera were not monophyletic, although the availability of genetic data is still fragmented.

Infection level of monogenean gill parasite, Diplozoon kashmirensis (Monogenea, Polyopisthocotylea) in the Crucian Carp, Carassius carassius from lake ecosystems of an altered water quality: What factors do have an impact on the Diplozoon infection?

Monogeneans are of great interest to the ecologists because of their simple life cycle and are considered as one of the important and sensitive parasites to any changes in water quality. The monogenean gill parasite, Diplozoon kashmirensis of the Carassius carassius was examined with the aim to evaluate the infection level and the factors influencing the infection. Our results showed that highest prevalence (34.22%) of D. kashmirensis was in the lake having high trophic status and least prevalence (10.90%) in the lake having least trophic status. Infection levels were significantly higher at the basins/sites having deteriorated water quality in comparison to the basins/sites having better water quality. The combined effect of pollutants and eutrophication showed decrease in intensity of D. kashmirensis in one of the polluted/hypertrophied site in the hypertrophic lake (Anchar Lake), while as synergistic effect (i.e. increase) on prevalence and intensity was observed in one of the polluted/hypertrophied site in the eutrophic lake (Dal Lake). Sex was not an important factor influencing the D. kashmirensis in three lakes. The study showed that condition factor was significantly higher in the hypertrophic lake and in an uninfected fish. In addition microhabitat influenced the Diplozoon infection. Most preferable site for the D. kashmirensis was middle sector of the gill. Furthermore, the gill parasite showed significantly positive correlation (r(p)=0.6, P<0.05) with water temperature in the hypertrophic lake, thus showing the impact of water temperature on this parasite. It was concluded that intra lake differences, season, condition factor, microhabitat and water temperature influenced the infection of D. kashmirensis. It seems from the data that eutrophic and hypertrophic habitats were favourable for the D. kashmirensis. The D. kashmirensis showed both antagonistic and synergistic response to the combined effect of pollution and eutrophication.