Chromosomal analysis of two Acanthodoras species (Doradidae, Siluriformes): Insights into the oldest thorny catfish clade and its karyotype evolution.

The Doradidae fishes constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and the sister group to all other thorny catfishes, and it includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, and the use of complementary approaches, including genetic studies, is an important step to better characterize this diversity and the relationships among the species within the genus. Therefore, we conducted a comprehensive analysis using conventional cytogenetic techniques and physical mapping of three multigene families (18S and 5S ribosomal DNA [rDNA], U2 small nuclear DNA [snDNA]) and four microsatellite motifs, namely (AC)n, (AT)n, (GA)n, and (GATA)n, in two sympatric species from the Negro River: Acanthodoras cataphractus and Acanthodoras cf. polygrammus. We found significant differences in constitutive heterochromatin (CH) content, distribution of the microsatellite (AT)n, and the number of 5S rDNA and U2 snDNA sites. These differences may result from chromosome rearrangements and repetitive DNA dispersal mechanisms. Furthermore, the characterization of the diploid number (2n) of these Acanthodoras species enables us to propose 2n = 58 chromosomes as the plesiomorphic 2n state in Doradidae based on ancestral state reconstruction. Acanthodoradinae is the oldest lineage of the thorny catfishes, and knowledge about its cytogenetic patterns is crucial for disentangling the karyotype evolution of the whole group. Thus, this study contributes to the understanding of the mechanisms behind chromosome diversification of Doradidae and highlights the importance of Acanthodoradinae in the evolutionary history of thorny catfishes.

Inter-annual and seasonal variations of the metazoan parasite communities of the blue sea catfish Ariopsis guatemalensis (Siluriformes: Ariidae), in a tropical coastal lagoon.

Parasitological studies of long-term inter-annual variations provide more precise and reliable information about the biological structure of fish parasite communities, and constitute a reference data base for future studies. A total of 1103 blue sea catfish Ariopsis guatemalensis from a tropical eutrophic coastal lagoon were examined for parasites over a 22-year period (from May 2000 to October 2022), to test the hypothesis that parasite communities of this host, should exhibit greater variations in their structure and species composition mainly over long-term periods. Three species of monoxenous (single-host life cycle), and nine of heteroxenous (multi-host life cycle) parasites were identified. The results indicated that parasite species composition of this catfish has remained stable over a 22-years period. However, the community structure has registered notable changes over periods of several years, mainly due to the replacement of the numerically dominant species. Temporal variations in the infection dynamics of component parasite species, were possibly caused by a combination of biotic and abiotic factors, influenced by the seasonal dry/rainy cycle, which can affect the availability of intermediate host populations, as well as the feeding and reproductive behavior of the host.

Species boundaries of the whiptail catfish Rineloricaria (Siluriformes: Loricariidae) from the Paraíba do Sul River drainage, southeastern Brazil, with species redescriptions and description of a new species.

Species of the catfish genus Rineloricaria are common in the Paraíba do Sul River basin, in southeastern Brazil; here we present a revision of the taxonomic diversity and geographic distribution of the species of the genus inhabiting the basin, based on novel morphologic and molecular data. Five species delimitation methods based on cytochrome C oxidase subunit 1 nucleotide sequences yielded comparable molecular operational taxonomic units. The automatic barcode gap discovery, assemble species by automatic partitioning, barcode index number, and Bayesian implementation of the Poisson tree process methods supported the recognition of five evolutionary lineages. These taxonomic units were assigned to the previously described Rineloricaria nigricauda, Rineloricaria steindachneri, Rineloricaria zawadzkii, and Rineloricaria nudipectoris, and an additional undescribed species. R. zawadzkii was further divided into two intraspecific geographically structured lineages using the generalized mixed Yule coalescent delimitation method. A maximum likelihood phylogenetic analysis revealed that the five lineages from the Paraíba do Sul have closer relationships to different species from southern and southeastern Brazil (Ribeira de Iguape, Lagoa dos Patos, Uruguay, Paraguay, and Parana river basins) than to each other. Based on the analysis of lectotypes, recently collected material, and specimens from ichthyological collections, the poorly described R. nigricauda and R. steindachneri are redescribed following current descriptive standards. The undescribed species from the middle and upper Paraíba do Sul River basin is formally described. The description of a new species, along with the description of species boundaries in R. nigricauda and R. steindachneri, contributes to the knowledge of the ichthyofauna of the Paraíba do Sul River basin and adjacent coastal drainages of southeastern Brazil. An identification key for the species of Rineloricaria occurring in the Paraíba do Sul River basin is provided.

Taxonomic revision of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), with descriptions of four new species.

A taxonomic revision of Sturisoma is presented. Individuals including both type and non-type specimens of all valid species were examined. Sturisoma was found to comprise 10 valid species: Sturisoma barbatum, Sturisoma brevirostre, Sturisoma graffini, Sturisoma guentheri, Sturisoma lyra, Sturisoma monopelte, Sturisoma nigrirostrum, Sturisoma reisi, Sturisoma rostratum, and Sturisoma tenuirostre. Furthermore, four new species are described: Sturisoma ghazziae, new species, from the Araguaia River, belonging to the Tocantins-Araguaia basin, Central Brazil; Sturisoma careirensia, new species, from the middle Amazon basin, Brazil; Sturisoma rapppydanielae, new species, from the Purus River, Amazon basin, Brazil; and Sturisoma defranciscoi, new species, from the Putumayo and Solimões rivers, upper Amazon basin, Colombia, and Brazil. Sturisoma robustum is confirmed as synonym of S. barbatum, species registered along the Paraguay/Parana/La Plata River basin in Argentina, Brazil, and Paraguay. New records were found for S. nigrirostrum as present in the upper Amazon basin, in the Yavari River, Brazil, in addition to its already known locality, the Ucayali River, Peru. The distribution of the type species of the genus S. rostratum is limited to the lower portion of the Amazon basin in the Araguaia, Maranhão, Mearim, Tapajós, and Tocantins rivers and its affluents, Brazil, in contrast to the assumed widespread distribution across the main basins of South America, as previously proposed for the species; the Mearim River is a new record for the species. Updated diagnoses and descriptions are offered for species of Sturisoma, in addition to distribution maps and an identification key for the species.

Molecular and morphometric data provide evidence of intraspecific variation in shape and pigmentation pattern in Otocinclus cocama (Siluriformes: Loricariidae) across major river drainages.

Otocinclus cocama, a uniquely colored species of the loricariid catfish genus Otocinclus described solely from the type locality in the lower Ucayali River in northern Peru, is reported occurring in the Tigre River, a tributary to the Marañón River that drains a different section of the Andean Mountain range in the western Amazon. Both populations differ in the number of dark bars spanning the flanks of the body, and we investigated whether these morphotypes constitute distinct species. The body shapes of populations from the Tigre and Ucayali rivers were compared using geometric morphometrics. Although principal component analysis detected a broad overlap between populations, multivariate analysis of variance and linear driscriminat analysis revealed a subtle differentiation between the populations of the two hydrographic basins. Average body shape of the Ucayali River population tend to be slightly higher than that of the Tigre River, with the caudal peduncle stretched vertically in the Ucayali population. Multivariate regression of shape and centroid size revealed an allometric effect of 10.7% (p < 0.001), suggesting that the variation between Tigre and Ucayali populations was purely shape variation. Molecular data of coI, cytb, nd2, and 16S mitochondrial genes indicated a nucleotide diversity range from 0.001 to 0.003, and haplotypic diversity range from 0.600 ± 0.11 to 0.79 ± 0.07. The median-joining haplotype network for the concatenated matrix exhibited two divergent haplogroups related to the geographic area and separated by <10 mutational steps. The molecular species delimitation methods based on distance (automatic barcode gap discovery and assemble species by automatic partitioning) recovered two molecular lineages evolving independently, being one of the lineages formed by individuals from both populations. Tree-based methods (generalized mixed Yule coalescent and Bayesian implementation of the Poisson tree process) recovered similar topologies and supported single lineage recognition. Methods of molecular delimitation of species disclosed the high similarity between the two populations of Otocinclus cocama, further supported by the presence of old haplotypes common to both groups which could indicate that the populations still maintain gene flow. Although the morphological data reveal a subtle variation between both river basins, the molecular data suggest a weak population structuration based on hydrographic areas, but not different species lineages, therefore Otocinclus cocama is composed of a single lineage with two distinct morphotypes.

Description and phylogenetic position of a new species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from the Jamanxim River basin

In this study, a new species of Rhyacoglanis is described from the Jamanxim River basin, Tapajós River basin. The new species differs from congeners based on the combination of the following diagnostic characters: two oblique dark bands formed by an agglomerate of melanophores on the predorsal region; dorsal confluence between the dark subdorsal and subadipose bands in large juveniles and adults; ventral confluence between the dark subadipose and caudal peduncle bands; body without conspicuous dark brown spots; complete dark band on caudal peduncle; body with three dark bands; a thin dark caudal-fin band; pectoral-fin spine with anterior serrae distributed along the entire margin; the posterior tip of the post-cleithral process reaching vertical through the base of the dorsal-fin spine; and hypural 5 free of hypural 3 and 4 and pointed caudal-fin lobes. Additionally, our molecular phylogenetic results using ultraconserved elements (UCEs) corroborate the new species as Rhyacoglanis and sister to an undescribed species of Rhyacoglanis from the Xingu River basin. Moreover, as pointed out in previous studies, we confirm Cruciglanis as a sister group to Pseudopimelodus plus Rhyacoglanis.(AU)

Neste estudo, uma nova espécie de Rhyacoglanis é descrita para a bacia do rio Jamanxim, bacia do rio Tapajós. A nova espécie difere de congêneres com base na combinação dos seguintes caracteres diagnósticos: duas faixas escuras oblíquas formadas por um aglomerado de melanóforos na região predorsal, confluência dorsal entre as faixas subdorsais escuras e subadiposas em adultos grandes, confluência ventral entre as faixas subadiposas escuras e do pedúnculo caudal em adultos grandes, corpo sem manchas escuras proeminentes de cor marrom, faixa escura completa no pedúnculo caudal, corpo com três faixas escuras e uma fina faixa escura na nadadeira caudal, espinho da nadadeira peitoral com serrilhas anteriores distribuídas ao longo de toda a margem, extremidade posterior do processo pós-cleitral atingindo verticalmente a base do espinho da nadadeira dorsal, hipural 5 livre dos hipurais 3 e 4 e lobos da nadadeira caudal pontiagudos. Adicionalmente, nossos resultados filogenéticos moleculares utilizando elementos ultraconservados (UCEs) corroboram a nova espécie como Rhyacoglanis é irmã de uma espécie não descrita de Rhyacoglanis da bacia do rio Xingu. Além disso, como apontado em estudos anteriores, confirmamos que Cruciglanis é um grupo irmão de Pseudopimelodus mais Rhyacoglanis.(AU)

A new species of Rineloricaria (Siluriformes: Loricariidae) from coastal drainages of Rio de Janeiro, southeastern Brazil

A new species of Rineloricaria is described from the Iguaçu, Magé, Saracuruna, Guapiaçu, Macacu, Macaé, and Paraíba do Sul River basins in southeastern Brazil based on morphological and molecular data. The new species is diagnosed among congeners by the combination of the following characters: absence of plates in most of the ventral surface of pectoral girdle; snout tip with elliptical naked area reaching posteriorly the anteriormost pore of the infraorbital ramus of sensory canal; dorsal-fin spinelet present; supraoccipital and predorsal plates with smooth keels; five series of lateral plates below the dorsal fin; median and mid-ventral series of plates with well-developed keels. The new species is distinguished from congeners that inhabit the rivers draining the Serra do Mar in Rio de Janeiro state by the partial plate coverage of the ventral surface of the pectoral girdle and the abdomen (vs. pectoral girdle and abdomen completely covered by plates in Rineloricaria nigricauda, R. steindachneri,and R. zawadzkii). The new species shares the absence of plates on the abdominal surface with other species from the Paraná, Uruguay, and other Brazilian coastal river basins.(AU)

Uma nova espécie de Rineloricaria é descrita das bacias dos rios Iguaçu, Magé, Saracuruna, Guapiaçu, Macacu, Macaé e Paraíba do Sul, no sudeste do Brasil, com base em caracteres morfológicos e moleculares. A nova espécie é diagnosticada entre as congêneres pela combinação dos seguintes caracteres: ausência de placas na maior parte da superfície ventral da cintura peitoral; extremidade do focinho com área nua elíptica estendida posteriormente, alcançando o poro mais anterior do canal sensorial infraorbital; presença de spinelet na origem da nadadeira dorsal; placas supraoccipitais e pré-dorsais com quilhas pouco proeminentes; cinco séries de placas laterais abaixo da origem da nadadeira dorsal; placas das séries mediana e médio-ventral com quilhas bem desenvolvidas. A nova espécie distingue-se das congêneres que habitam os rios que drenam a Serra do Mar no Estado do Rio de Janeiro pela cobertura parcial de placas da superfície ventral da cintura peitoral e do abdômen (vs. cintura peitoral e abdômen completamente cobertos por placas em Rineloricaria nigricauda, R. steindachneri e R. zawadzkii). A nova espécie compartilha a ausência de placas na superfície abdominal com outras espécies das bacias hidrográficas dos rios Paraná e Uruguai e rios costeiros do Brasil.(AU)

An integrative approach method reveals the presence of a previously unreported species of Imparfinis Eigenmann and Norris 1900 (Siluriformes: Heptapteridae) in Argentina.

Specimens of Imparfinis were recently collected in north-western Argentina from the Bermejo River basin (Salta and Jujuy Provinces), del Valle River (Salta Province) and Horcones River (Santiago del Estero Province). An integrative approach to taxonomy, combining a detailed morphological study and molecular phylogenetic analyses, was applied to determine the species identity of these specimens. A principal components analysis of morphological data clustered the specimens from north-western Argentina and from the Amazon basin, indicating a close morphological resemblance. Also, a molecular phylogenetic analysis showed populations of I. guttatus from Argentina and Peru forming a clade. According to the conducted haplotype network analysis these populations are distinct in two mutations. Thus, in the absence of morphological or molecular data indicating the contrary, the combined method supports the identity of the specimens from the tributaries of the Paraguay River in Argentina as I. guttatus, whose type locality is in the upper Beni River basin in Bolivia. This contribution is also the first record for this species from Argentina. The disjunct distribution of I. guttatus provides new evidence reinforcing the hypothesis for the origin of the Paraguayan ichthyofauna. We also provide an approach to the phylogenetic relationships of Imparfinis in Heptapteridae.

Robertsonian Fusion Site in Rineloricaria pentamaculata (Siluriformes: Loricariidae): Involvement of 5S Ribosomal DNA and Satellite Sequences.

Cytogenetic studies demonstrated that unstable chromosomal sites in armored catfishes (Loricariidae) triggered intense karyotypic diversification, mainly derived from Robertsonian rearrangements. In Loricariinae, the presence of ribosomal DNA (rDNA) clusters and their flanking repeated regions (such as microsatellites or partial transposable element sequences) was proposed to facilitate chromosomal rearrangements. Hence, this study aimed to characterize the numerical chromosomal polymorphism observed in Rineloricaria pentamaculata and evaluate the chromosomal rearrangements which originated diploid chromosome number (2n) variation, from 56 to 54. Our data indicate a centric fusion event between acrocentric chromosomes of pairs 15 and 18, bearing 5S rDNA sites on their short (p) arms. This chromosome fusion established the numerical polymorphism, decreasing the 2n from original 56 (karyomorph A) to 55 in karyomorph B and 54 in karyomorph C. Although vestiges of telomeric sequences were evidenced at the fusion point, no 5S rDNA was detected in this region. The acrocentric chromosomes involved in the origin of the fusion were enriched with (CA)n and (GA)n microsatellites. Repetitive sequences in the acrocentric chromosomes subtelomeres have facilitated the rearrangement. Our study thus reinforces the view on the important role of particular repetitive DNA classes in promoting chromosome fusions which frequently drive Rineloricaria karyotype evolution.

New species of Phenacorhamdia (Siluriformes: Heptapteridae) from the Xingu River basin

Heptapteridae is a diverse group of catfishes composed of 231 valid species endemic to the Neotropical region, recognized in two subfamilies: Rhamdiinae and Heptapterinae. Phenacorhamdia is a Heptapterinae member and currently has 13 valid species broadly distributed throughout the main river basins of South America. Here we described a new species of Phenacorhamdia from the Xingu River basin. Morphological data were obtained from 30 specimens under 23 morphometric measures and 6 meristic counts. The new species differs from congeners based on the exclusive combination of the following diagnostic characters: atypical mottled colored body and all fins with interradial membranes mottled pigmented; multicuspid teeth; maxillary barbel reaching pectoral-fin origin; lacking a short extension of the first pectoral-fin ray; caudal fin lobes extremely elongated and pointed; and 43−45 total vertebrae.(AU)

Heptapteridae é um grupo diverso de bagres neotropicais composto por 231 espécies válidas, endêmicas da região Neotropical, divididas em duas subfamílias: Rhamdiinae e Heptapterinae. Phenacorhamdia é um membro de Heptapterinae e atualmente possui 13 espécies válidas amplamente distribuídas pelos principais rios da América do Sul. Aqui nós descrevemos uma nova espécie de Phenacorhamdia da bacia do rio Xingu. Dados morfológicos foram obtidos de 30 espécimes, 23 medidas morfométricas e seis contagens merísticas. A nova espécie é diferenciada de suas congêneres com base na seguinte combinação de características: um atípico corpo manchado com as membranas interradiais de todas as nadadeiras manchadas; dentes multicuspidados; barbilhão maxilar atingindo a origem da nadadeira peitoral; ausência de uma curta extensão do primeiro raio da nadadeira peitoral; lóbulos da nadadeira caudal extremamente alongados e pontiagudos, e 43−45 vértebras.(AU)

New arrangement of three genera of fish tapeworms (Cestoda: Proteocephalidae) in catfishes (Siluriformes) from the Neotropical Region: taxonomic implications of molecular phylogenetic analyses.

Tapeworms (Cestoda: Proteocephalidae) are the dominant component of communities of intestinal parasites in pimelodid and other catfishes (Siluriformes) from South America. Even though these parasites have been studied intensively over more than one century, molecular taxonomy and phylogenetics have questioned their morphology-based classification, thus raising doubts about the systematic value of traits commonly used to circumscribe individual taxa. In the present study, members of three morphologically well-characterized genera of proteocephalids from pimelodid (Hemisorubim platyrhynchos and Sorubim lima) and auchenipterid (Ageneiosus inermis) catfishes from the Paraná or Amazon River basins were subjected to DNA sequencing of the large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI). Phylogenetic analyses revealed the sister relationship between Manaosia bracodemoca and Mariauxiella piscatorum, and among Mariauxiella pimelodi and Ageneiella brevifilis. As a result, Mar. piscatorum and A. brevifilis are transferred to Manaosia and Mariauxiella, respectively, as Manaosia piscatorum n. comb. and Mariauxiella brevifilis n. comb., and the genus Ageneiella is suppressed. Diagnoses of Manaosia and Mariauxiella are amended. In addition, the present study revealed misidentification of tapeworms whose sequences are deposited in the GenBank database.

A new species of Loricaria (Siluriformes: Loricariidae) from the Turiaçu River basin, Eastern Amazon region, Brazil.

A new species of Loricaria is herein described from the Turiaçu River basin, Eastern Amazon region, Maranhão state, Brazil, within the Maranhão Hydrological Unit (MHU). Loricaria turi differs from its congeners mainly by the following combination of characters: abdominal plate development confined to the posterior median region, pectoral girdle mostly naked, with cluster of plates near pectoral fin bases; large eyes (minimum orbital diameter 16.2-20.7% of HL and maximum orbital diameter 19.8-24.0% of HL), 214.4 mm of maximum standard length, and large basicaudal plate (16.6-29.2% of HL). The description of this new species strengthens the hypothesis that the Maranhão Hydrological Unit (MHU) is a possible area of endemism for freshwater fishes and contributes to the knowledge of the freshwater fish diversity and composition of the region.

Three New Species of Cosmetocleithrum (Monogenea: Dactylogyridae) Gill Parasites of Trachelyopterus galeatus (Siluriformes: Auchenipteridae) in Southeastern Brazil.

PURPOSE: To describe three new species of Cosmetocleithrum in the gills of Trachelyopterus galeatus (Siluriformes, Auchenipteridae) from Aguapeí River, Upper Paraná River basin, São Paulo State, Brazil. METHODS: Fifty-three specimens of T. galeatus were captured in the mouth of the Aguapeí River from August 2013 to June 2014. Monogeneans were mounted unstained in Hoyer's and Gray and Wess's medium. RESULTS: Cosmetocleithrum spathulatum sp. n., Cosmetocleithrum baculum sp. n., and Cosmetocleithrum galeatum sp. n. differ from all known congeneric species mainly in the morphology of the accessory piece (i.e. spatulate-shaped, claviform, and a straight rod with hook-shaped distal portion, respectively). Also, the three new species share hooks with different sizes with hooks pairs 5 and 7 bigger than others and with an erect delicate point, inconspicuous thumb, longer shaft, and slender shank. CONCLUSIONS: To date, 18 species of Cosmetocleithrum were recognised parasitizing siluriforms in the Neotropical region. The present study expands the number to 21 species, however, despite this increase, the number of known taxa of monogeneans in neotropics is far from representing the ideal situation.

Hypostomus hermanni redescription and a new species of Hypostomus (Siluriformes: Loricariidae) from Upper Paraná River basin, Brazil

A redescription of Hypostomus hermanni is presented herein along with the description of a new species of Hypostomus, which is apparently endemic to the Ivaí River basin, a tributary of the Upper Paraná River basin, Brazil. Hypostomus hermanni is diagnosed from congeners mainly by having: usually large black blotches on body and fins; absence of keels on compound pterotic, on pre-dorsal plates, and on lateral series of bony plates; by having parieto-supraoccipital and predorsal region flat; and by having less than 46 teeth per each premaxilla or dentary ramus. The new species is distinguished from congeners9au0 mainly for lacking conspicuous blotches, parieto-supraoccipital non-carinate, and villiform bicuspid teeth.

Uma redescrição de Hypostomus hermanni é aqui apresentada, juntamente com a descrição de uma nova espécie de Hypostomus, que é aparentemente endêmica da bacia do rio Ivaí, afluente do alto rio Paraná, Brasil. Hypostomus hermanni é diagnosticada de suas congêneres principalmente por apresentar: geralmente grandes manchas pretas ao longo do corpo e nadadeiras; ausência de quilhas no pterótico-composto, nas placas pré-dorsais e nas séries laterais de placas ósseas; por ter as regiões do parieto-supraoccipital e predorsal planas; e por ter menos que 46 dentes por cada ramo premaxilar ou dentário. A espécie nova distingue-se de suas congêneres principalmente pela ausência de manchas conspícuas no corpo, e supraocciptal não quilhado e dentes viliformes bicuspidados.(AU)

Hypostomus hermanni redescription and a new species of Hypostomus (Siluriformes: Loricariidae) from Upper Paraná River basin, Brazil

A redescription of Hypostomus hermanni is presented herein along with the description of a new species of Hypostomus, which is apparently endemic to the Ivaí River basin, a tributary of the Upper Paraná River basin, Brazil. Hypostomus hermanni is diagnosed from congeners mainly by having: usually large black blotches on body and fins; absence of keels on compound pterotic, on pre-dorsal plates, and on lateral series of bony plates; by having parieto-supraoccipital and predorsal region flat; and by having less than 46 teeth per each premaxilla or dentary ramus. The new species is distinguished from congeners9au0 mainly for lacking conspicuous blotches, parieto-supraoccipital non-carinate, and villiform bicuspid teeth.

Uma redescrição de Hypostomus hermanni é aqui apresentada, juntamente com a descrição de uma nova espécie de Hypostomus, que é aparentemente endêmica da bacia do rio Ivaí, afluente do alto rio Paraná, Brasil. Hypostomus hermanni é diagnosticada de suas congêneres principalmente por apresentar: geralmente grandes manchas pretas ao longo do corpo e nadadeiras; ausência de quilhas no pterótico-composto, nas placas pré-dorsais e nas séries laterais de placas ósseas; por ter as regiões do parieto-supraoccipital e predorsal planas; e por ter menos que 46 dentes por cada ramo premaxilar ou dentário. A espécie nova distingue-se de suas congêneres principalmente pela ausência de manchas conspícuas no corpo, e supraocciptal não quilhado e dentes viliformes bicuspidados.(AU)

A new species of Phenacorhamdia Dahl 1961 (Siluriformes: Heptapteridae) from the Paranapanema River basin, southeastern Brazil.

A new species of Phenacorhamdia is described from Paranapanema River, Upper Paraná River basin, southeastern Brazil. The new species is distinguished from congeners by the combination of following characters 45-46 vertebrae; an entirely dark-brown body; nine pleural ribs; eight branched rays in upper lobe of caudal fin; seven branched rays in pectoral fin; 13 anal-fin rays with 9-10 branched; first basal radial inserted at the 13th vertebrae and eight branchiostegal rays.

Two new species of Pseudopimelodus Bleeker, 1858 (Siluriformes: Pseudopimelodidae) from the Magdalena Basin, Colombia.

The family Pseudopimelodidae is widely distributed in South America and includes 51 described species organized in seven genera. Only two of four species of the genus Pseudopimelodus have been recorded for the trans-Andean basins of Colombia, Pseudopimelodus bufonius and P. schultzi, whose similarity in external morphology make their identification difficult. We performed a phylogenetic analysis using a fragment of the Cytochrome C Oxidase subunit 1 gene (COI), and analyzed osteological and traditional morphometric characters to study Pseudopimelodus from the Colombian trans-Andean region. Results provided strong support for two clades phylogenetically related to Pseudopimelodus, that showed clear-cut molecular, osteological, and morphometric differences from previously described bumblebee catfishes. Based on these results, we describe two Pseudopimelodus species from the Magdalena-Cauca River Basin: P. magnus sp. nov. with 43-44 vertebrae, dorsal-fin spine with serrations on its anterior margin; lateral margin of transverse process of the fourth vertebra of the Weberian complex forming an acute angle in ventral view and P. atricaudus sp. nov. with 39 vertebrae, dorsal-fin spine smooth on its anterior margin and a dark, vertical band covering 3/4 of the caudal fin with base of rays and tip of caudal-fin lobes hyaline.

Trinigyrus spp. (Monogenea: Dactylogyridae) from Brazilian catfishes: new species, molecular data and new morphological contributions to the genus.

This study describes two new species, Trinigyrus anthus n. sp. and Trinigyrus carvalhoi n. sp., from gills of Hypostomus spp. from the Upper Paraná River basin, Brazil. Trinigyrus peregrinus is redescribed based on examination of its holotype, paratypes and new material of specimens parasitizing Pterygoplichthys ambrosettii, also from the Upper Paraná River basin, Brazil. New morphological features were included in the diagnosis of the genus, such as the presence of a sclerotized border on the anchor base, and a weakly sclerotized fringe on the base of the male copulatory organ (MCO). Trinigyrus anthus n. sp. differs from other congeners by the shape of the MCO, presenting an enlarged base with sclerotized fringes resembling flower petals. Trinigyrus carvalhoi n. sp. and T. peregrinus are similar but can be differentiated from each other mainly by the sclerotization of the vagina (absent in the new species), and the morphology of the MCO (C-shaped versus one counterclockwise circle, respectively). For the first time, gene sequences of Trinigyrus spp. from Brazil were obtained (partial ribosomal 28S and mitochondrial cytochrome c oxidase I (mtCOI)). The genetic divergences among the new species and T. peregrinus varied from 2 to 3% (6‒18 pb) based on sequences of 28S ribosomal DNA (rDNA), and 6-7% (83‒92 pb) using mtCOI. Phylogenetic analyses based on partial 28S rDNA revealed that Trinigyrus, Heteropriapulus and Unilatus formed a monophyletic and well-supported clade of monogeneans from Neotropical freshwater loricariids, suggesting a closer relationship among these dactylogyrids and their hosts.

Diversity of helminth parasites of eight siluriform fishes from the Aguapeí River, upper Paraná basin, São Paulo state, Brazil.

Fishes of the order Siluriformes, known as catfishes, have a global distribution with more than 3,600 valid species of which 2,087 occur in the Neotropical region. Despite being highly diverse, abundant, and of economic importance as food and ornamental fishes, knowledge about the diversity and distribution of their helminth parasites is fragmentary and scarce. Eight species of catfishes (Pterodoras granulosus, Trachydoras paraguayensis, Pimelodella avanhandavae, Loricariichthys platymetopon, Pterygoplichthys ambrosettii, Rhinelepis aspera, Hemisorubim platyrhynchos, and Sorubim lima) from the Aguapeí River, Upper Paraná River basin, municipality of Castilho, São Paulo State, Brazil, were surveyed for helminth parasites. Collected fishes were weighed, measured, and examined for helminth parasites following standard methodology. Fifty helminth parasite taxa (23 monogeneans, 13 digeneans, 11 nematodes, and three cestodes) were found from a total of 405 fishes screened. The helminth taxon that showed the highest mean intensity of infection and mean abundance was the nematode Rondonia rondoni from P. granulosus, followed by the nematode Parasynodontisia petterae from R. aspera. The ecological analyses were carried out at the component community level and at the infracommunity level. Trachydoras paraguayensis had the richest helminth component community. Pterygoplichthys ambrosettii had the most diverse helminth component community and R. aspera had the lowest. Both hosts are loricariids and have similar diet. However, the high parasite diversity of P. ambrosettii is due to the number of dactylogyrids species found (10), which are directly transmitted, whereas only three dactylogyrid species were found in R. aspera. At infracommunity level, the nematode species R. rondoni and P. petterae dominated the parasite communities. This study presents 38 new host records, contributing considerably to increase the diffuse knowledge of helminth parasites of Neotropical siluriforms.

A new species of Parotocinclus with reduced adipose fin (Loricariidae: Hypoptopomatinae), from the rio Jacuípe basin, Bahia State, Brazil

ABSTRACT A new species of Parotocinclus, apparently endemic to the rio Jacuípe basin, Bahia State, Brazil, is described. The new species is distinguished from congeners, except P. bidentatus, P. cabessadecuia, P. dani, P. halbothi, P. muriaensis, P. pentakelis, P. seridoensis, and P. spilurus, by the presence of a reduced adipose fin. The new species differs from the aforementioned species by the absence of unicuspid accessory teeth, abdomen with broad naked areas between lateral and medial patches of plates, and snout tip completely covered by plates and odontodes. The adipose fin of the new species is restrict solely to the adipose-fin spine, lacking the adipose-fin membrane, a reduction pattern previously described to P. halbothi, a congener from rivers of the Amazonas and Marowijne basins.

RESUMO Uma espécie nova de Parotocinclus, aparentemente endêmica da bacia do rio Jacuípe, Estado da Bahia, Brasil, é descrita. A espécie nova se distingue de suas congêneres, exceto P. bidentatus, P. cabessadecuia, P. dani, P. halbothi, P. muriaensis, P. pentakelis, P. seridoensis e P. spilurus, pela presença de nadadeira adiposa reduzida. A nova espécie difere das espécies mencionadas anteriormente pela ausência de dentição acessória unicúspide, abdômen com amplas áreas nuas entre o grupo de placas laterais e o grupo de placas medianas e ponta do focinho completamente coberta por placas e odontódeos. A nadadeira adiposa da nova espécie é restrita somente ao espinho, sem a membrana da adiposa, um padrão de redução descrito para P. halbothi, uma congênere de rios da bacia Amazônica e da bacia do rio Marowijne.