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.

Unraveling the complex phylogeographic history of freshwater fishes in Lower Central America: A study of the electric fish Brachyhypopomus occidentalis.

Lower Central America (LCA) has a complex biogeographic history shaped by the rise of the Isthmus of Panama and the global climatic oscillations of the Pleistocene. These events have been crucial in structuring biodiversity in LCA, but their consequences for the distribution and partitions of genetic diversity across the region remain to be elucidated. We combined complete mitochondrial genomes and nuclear ultraconserved elements (UCEs) to study the phylogeographic history and population genetic structure of the electric fish Brachyhypopomus occidentalis in LCA. Our results are consistent with the known phylogeographic history of B. occidentalis in LCA, but we update this history in several important ways that help illuminate the phylogeographic history of freshwater fishes in the region. We provide: i) support for three waves of colonization, two of which occurred prior to the final closure of the Panama Isthmus; ii) a more precise understanding of each colonization event, with evidence for a larger footprint of the first event, as well as genetic exchange across the continental divide in subsequent events; and iii) evidence for high levels of previously unrecognized population genetic structure across LCA. This updated model of colonization and diversification of B. occidentalis consists of three waves of dispersal and colonization, which triggered the evolution of geographic breaks in both nuclear and mitochondrial genomes across LCA. These processes are tightly linked to the dynamic uplift of the Isthmus, recent volcanic activity in the region, and the sea-level oscillations of the Pleistocene. These results improve previous phylogeographic inferences regarding the distribution and diversification of freshwater fishes in LCA, and generate testable hypotheses to guide future research exploring the factors shaping biodiversity in the region.

New and previously known ectoparasitic monogenoids (Platyhelminthes) on native and non-native fishes from tributaries of the Usumacinta River basin (southern Mexico), a Neotropical transition zone.

During a research on morphological diversity of gill ectoparasites on native and non-native fishes from tributaries (Palizada, El Recreo and Lacantún rivers) of the Usumacinta River Basin in the states of Campeche, Tabasco, and Chiapas (southern Mexico), the following monogenoids were found: Icelanonchohaptor tropicalis n. sp. on Usumacinta buffalo Ictiobus meridionalis (Günther, 1868) (Catostomidae); Heteropriapulus simplexiodes n. sp. and Heteropriapulus heterotylioides n. sp. on catfishes Pterygoplichthys pardalis (Castelnau, 1855) (Loricariidae) (type host) and Pterygoplichthys disyunctivus (Weber, 1991); Ligictaluridus mirabilis (Mueller 1937; Klassen and Beverley-Burton1985 from the southern blue catfish Ictalurus meridionalis (Günther, 1864) (Ictaluridae); Aristocleidus mexicanus Mendoza-Franco and Vidal-Martínez, 2001 on Eugerres mexicanus (Steindachner, 1863) (Gerreidae) (all monogenoidean species in the Dactylogyridae); and Diplectanocotyla megalopis Rakotofiringa and Oliver1987 (Diplectanidae) on tarpon Megalops atlanticus Valenciennes, 1847 (Megalopidae). The new species of Icelanonchohaptor and Heteropriapulus are herein described for the first time from a native catostomid and non-native Pterygoplichthys spp., respectively. While I. tropicalis n. sp. and L. mirabilis are morphologically comparable with their congeners from the Nearctic (i.e., United States and Canada), all other monogenoids exhibited Neotropical affinities. Present study shown that the gill monogenoids on native and non-native fishes in the Neotropical Mexican transition zone of the Usumacinta River basin are equally represented by species with Nearctic and Neotropical affinities including those adapted to freshwater environment in this area from marine ancestry.

A regional scale study of parasites in Percichthys trucha, an endemic fish of southern South America: insights on diversity and distribution from two decades of field surveys.

The current conservation status of Percichthys trucha (Creole perch) is Least Concern, although the population trend is considered to be decreasing. We conducted an extensive survey of parasite fauna in this species over two decades in its distribution range in Argentina. Fish were collected using gill and trawl nets. Parasites were collected, identified, and counted to calculate prevalence and mean intensity. The present work reports the parasite species infecting P. trucha, using data from our own survey and from previously published records. This information enables us to evaluate infection and distribution patterns, assess the role of P. trucha as host, determine the specificity of the parasites, and evaluate the threat represented by introduced, invasive parasites. The data set consists of a total of 453 host-parasite-locality records, of which only 15 are exclusively bibliographic. We found 44 parasite taxa: 19 digeneans, 4 monogeneans, 5 cestodes, 8 nematodes, 4 acanthocephalans, 3 crustaceans, and 1 mollusk. The most represented families were Diplostomidae, Heterophyidae, and Dactylogyridae. This study increases the number of parasite species known from 25 to 44. It can be concluded that this parasite fauna is characterized by high diversity, particularly of digeneans, and most of the parasites reproduce within this host, a pattern which is related to the top position of this fish species in the trophic webs. Six parasite species (Allocreadium patagonicum, Homalometron papilliferum, Acanthostomoides apophalliformis, Duplaccessorius andinus, Pseudodelphys limnicola, and Hysterothylacium patagonense) exhibit high host specificity (only matures in Creole perches) and are widely distributed, which could now be considered as "biogeographical core helminth fauna." Some P. trucha populations are affected by the invasion of alien fishes like Cyprinus carpio and pathogenic parasites like Lernaea cyprinacea and Schizocotyle acheilognathi. Our findings emphasize the need for further research.

Speciation in Coastal Basins Driven by Staggered Headwater Captures: Dispersal of a Species Complex, Leporinus bahiensis, as Revealed by Genome-wide SNP Data.

Past sea level changes and geological instability along watershed boundaries have largely influenced fish distribution across coastal basins, either by dispersal via palaeodrainages now submerged or by headwater captures, respectively. Accordingly, the South American Atlantic coast encompasses several small and isolated drainages that share a similar species composition, representing a suitable model to infer historical processes. Leporinus bahiensis is a freshwater fish species widespread along adjacent coastal basins over narrow continental shelf with no evidence of palaeodrainage connections at low sea level periods. Therefore, this study aimed to reconstruct its evolutionary history to infer the role of headwater captures in the dispersal process. To accomplish this, we employed molecular-level phylogenetic and population structure analyses based on Sanger sequences (5 genes) and genome-wide SNP data. Phylogenetic trees based on Sanger data were inconclusive, but SNPs data did support the monophyletic status of L. bahiensis. Both COI and SNP data revealed structured populations according to each hydrographic basin. Species delimitation analyses revealed from 3 (COI) to 5 (multilocus approach) MOTUs, corresponding to the sampled basins. An intricate biogeographic scenario was inferred and supported by Approximate Bayesian Computation (ABC) analysis. Specifically, a staggered pattern was revealed and characterized by sequential headwater captures from basins adjacent to upland drainages into small coastal basins at different periods. These headwater captures resulted in dispersal throughout contiguous coastal basins, followed by deep genetic divergence among lineages. To decipher such recent divergences, as herein represented by L. bahiensis populations, we used genome-wide SNPs data. Indeed, the combined use of genome-wide SNPs data and ABC method allowed us to reconstruct the evolutionary history and speciation of L. bahiensis. This framework might be useful in disentangling the diversification process in other neotropical fishes subject to a reticulate geological history.

Bilateral genital asymmetry in livebearer fishes of the genus Phalloceros Eigenmann, 1907, with description of a new species from coastal drainages of southern Brazil (Cyprinodontiformes: Poeciliidae).

A new species of Phalloceros is described from the Tijucas, Maruim, Aririú, Cubatão do Sul, Rio da Madre, D'Una and Tubarão river basins in southern Brazil. The new species is diagnosed among congeners by the bilateral asymmetry of a hood-like structure located immediately anterior to the urogenital papilla of females. The hood is fused with the urogenital papilla on the right side, but free from the papilla on the left side. This hood is reported for the first time in the genus and is present in six of the 21 valid species of Phalloceros, but its bilateral asymmetry is an exclusive condition of the new species. These species do not constitute a monophyletic group. The new species is likely to be phylogenetically related to P. caudimaculatus, whose females have a symmetrical hood.

A new species of mailed catfish of genus Rhadinoloricaria (Siluriformes: Loricariidae: Loricariinae) from Rio Negro basin, Brazil.

During a recent collection expedition to the Rio Negro, in the state of Amazonas, Brazil, eight individuals of an unknown species were collected, with a combination of characteristics that placed the species in the genus Rhadinoloricaria. Furthermore, the presence of two autapomorphic characteristics, including numerous elongated papillae on the lower lip and unbranched barbelets on the margin of lower lip, suggests that it is a new species. From morphological and phylogenetic analyses, including the sequencing of specific genes to calculate the maximum likelihood analyses, coupled with osteological computed tomography (CT) scan analyses, the authors corroborated that the specimens represent a new species of Rhadinoloricaria, described in the present study.

Genetic population structure of Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) and evidence of temporal variation in structure.

Surubim (Pseudoplatystoma corruscans, Pimelodidae) are migratory catfish native to the rivers in the La Plata and São Francisco basins. They are piscivores that attain considerable body sizes and are a valuable economic resource. Surubim exhibits extensive migrations during its life cycle that may affect the population structure at vast geographic scales. The authors examined the genetic diversity and population genetic structure of P. corruscans using microsatellite markers from a comprehensive sampling of 260 individuals from the Upper and Lower Paraná River. They identified two well-differentiated genetic clusters corresponding to a natural geographic barrier historically separating Upper and Lower Paraná regions. They also demonstrated temporal variation in population genetic structure at a site in Lower Paraná close to the confluence with the Paraguay River, most likely explained by the influx of migrant fishes at certain times of the year.

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)

Morphometric and molecular differentiation of Pimelodus grosskopfii and Pimelodus yuma (Siluriformes: Pimelodidae)

Pimelodus grosskopfii and Pimelodus yuma, two species endemic to the Magdalena-Cauca basin in Colombia, overlap in the ranges of some of their diagnostic characters, which hampers their correct morphological identification. Aiming to help discriminate these species, this study conducted an integrative analysis using traditional and geometric morphometrics, phylogenetic analysis based on partial sequences of the mitochondrial cytochrome c oxidase subunit 1 gene (COI, cox1) and the identification of diagnostic Single Nucleotide Polymorphism markers (SNP). The species differ significantly in body geometry, allowing 100% discrimination, which was reinforced by a phylogenetic analysis that recovered well-supported monophyly of each species (posterior probability > 0.95). Additionally, the traditional morphometric results corroborated some previously reported diagnostic traits for both species and let us describe one non-overlapping ratio related to the adipose fin length. Three of five SNP markers had reciprocally exclusive alleles suitable for identifying each species. The morphometric and molecular methods conducted in this study constitute alternative tools for the correct discrimination of P. grosskopfii and P. yuma in the wild and in captive populations used for aquaculture.(AU)

Pimelodus grosskopfii y Pimelodus yuma, dos especies endémicas de la Cuenca Magdalena-Cauca en Colombia, se superponen en los rangos de variación de algunos de sus caracteres diagnósticos, lo que dificulta su correcta diferenciación morfológica. Con el objetivo de contribuir a la discriminación de estas especies, se realizó un análisis integrativo utilizando la morfometría geométrica y tradicional, análisis filogenético basado en secuencias parciales del gen mitocondrial citocromo c oxidasa subunidad I (COI, cox1) y la identificación de marcadores diagnósticos de polimorfismo de nucleótido único (SNP). Las especies difieren significativamente en la geometría del cuerpo, permitiendo una discriminación del 100%, lo que fue reforzado por un análisis filogenético que recuperó una monofilia bien soportada para cada especie (probabilidad posterior > 0,95). Además, los resultados de la morfometría tradicional corroboraron algunos rasgos diagnósticos previamente reportados para ambas especies y nos permitieron describir una proporción que no se sobrepone, relacionada con la longitud de la aleta adiposa. Tres de los cinco marcadores SNP poseían alelos recíprocamente exclusivos, adecuados para identificar cada especie. Los métodos morfométricos y moleculares implementados en este estudio constituyen herramientas alternativas para la correcta discriminación de P. grosskopfii y P. yuma tanto en la naturaleza como en poblaciones cautivas utilizadas para la acuicultura.(AU)

Lista de especies de peces de la cuenca del río Ucayali, Perú

En este trabajo se presenta una lista actualizada de los registros de especies de peces de la cuenca del río Ucayali, Perú, provenientes de datos publicados y no publicados. Los resultados muestran que la cuenca del Ucayali presenta una ictiofauna rica y diversificada con el registro de 734 especies distribuidas en 15 órdenes, 49 familias y 292 géneros. La Ictiofauna está compuesta por peces miniatura (4%), peces pequeños (39%), medianos (41%), grandes (13%) y gigantes (3%). Los grupos dominantes son los Characiformes (312 especies, 43.0 %), Siluriformes (270 especies, 36.8%), Gymnotiformes (51 especies, 6.9%), y Cichliformes (50 especies, 6.8%). Parte de la ictiofauna es compartida con cuencas adyacentes como Marañón, y Amazonas peruano, principalmente en la región de confluencia, lo que contribuye a la notable diversidad de peces en la cuenca. Se observó una alta riqueza de especies con distribución restricta de los géneros Orestias, Astroblepus, Trichomycterus, Hemibrycon, entre otras especies, que ocurren en la región de cabeceras. Estimativos de riqueza de especies considerando su distribución por cada 100 m de altitud, indican que la cuenca del Ucayali esta subestimada, esperándose encontrar hasta 1125 especies. Los resultados aquí presentados son antecedentes que coadyuvaran a la toma de decisiones con fines de conservación y desarrollo sustentable en la región amazónica.

This study presents an updated checklists of the fish species recorded in the Ucayali River basin, Peru, from published and unpublished data. Ucayali River basin shows a rich and diversified ichthyofauna, with 734 species distributed in 15 orders, 49 families and 292 genera. It is composed by miniature fishes (4 %, < 2.6 cm of standard length), small fishes (39 %), medium fishes (41 %), large fishes (13 %) and giants (3 %). The dominant groups are Characiformes (312 species, 43.0 %), Siluriformes (270 species, 36.8 %), Gymnotiformes (51 species, 6.9 %) and Cichliformes (50 species, 6.8 %). Part of the ichthyofauna is shared with the adjacent basins as Marañón and Amazon, mainly in the confluence area, which contribute to the highest diversity of fishes in the Ucayali basin. High diversity of fishes with restricted distribution was observed, among them Orestias, Astroblepus, Trichomycterus, Hemibrycon genera that occur in the headwaters. Estimates of species richness considering their distribution per 100 m of altitude, show that the Ucayali basin is underestimated, expecting to find up to 1125 species. The results presented here are background information that will contribute to decision-making for conservation and sustainable development purposes in the Amazon region.

Genome-wide species delimitation analyses of a silverside fish species complex in central Mexico indicate taxonomic over-splitting.

BACKGROUND: Delimiting species across a speciation continuum is a complex task, as the process of species origin is not generally instantaneous. The use of genome-wide data provides unprecedented resolution to address convoluted species delimitation cases, often unraveling cryptic diversity. However, because genome-wide approaches based on the multispecies coalescent model are known to confound population structure with species boundaries, often resulting in taxonomic over-splitting, it has become increasingly evident that species delimitation research must consider multiple lines of evidence. In this study, we used phylogenomic, population genomic, and coalescent-based species delimitation approaches, and examined those in light of morphological and ecological information, to investigate species numbers and boundaries comprising the Chirostoma "humboltianum group" (family Atherinidae). The humboltianum group is a taxonomically controversial species complex where previous morphological and mitochondrial studies produced conflicting species delimitation outcomes. We generated ddRADseq data for 77 individuals representing the nine nominal species in the group, spanning their distribution range in the central Mexican plateau. RESULTS: Our results conflict with the morphospecies and ecological delimitation hypotheses, identifying four independently evolving lineages organized in three geographically cohesive clades: (i) chapalae and sphyraena groups in Lake Chapala, (ii) estor group in Lakes Pátzcuaro and Zirahuén, and (iii) humboltianum sensu stricto group in Lake Zacapu and Lerma river system. CONCLUSIONS: Overall, our study provides an atypical example where genome-wide analyses delineate fewer species than previously recognized on the basis of morphology. It also highlights the influence of the geological history of the Chapala-Lerma hydrological system in driving allopatric speciation in the humboltianum group.

Competitive Exclusion Bacterial Culture Derived from the Gut Microbiome of Nile Tilapia (Oreochromis niloticus) as a Resource to Efficiently Recover Probiotic Strains: Taxonomic, Genomic, and Functional Proof of Concept.

This study aims to mine a previously developed continuous-flow competitive exclusion culture (CFCEC) originating from the Tilapia gut microbiome as a rational and efficient autochthonous probiotic strain recovery source. Three isolated strains were tested on their adaptability to host gastrointestinal conditions, their antibacterial activities against aquaculture bacterial pathogens, and their antibiotic susceptibility patterns. Their genomes were fully sequenced, assembled, annotated, and relevant functions inferred, such as those related to pinpointed probiotic activities and phylogenomic comparative analyses to the closer reported strains/species relatives. The strains are possible candidates of novel genus/species taxa inside Lactococcus spp. and Priestia spp. (previously known as Bacillus spp.) These results were consistent with reports on strains inside these phyla exhibiting probiotic features, and the strains we found are expanding their known diversity. Furthermore, their pangenomes showed that these bacteria have indeed a set of so far uncharacterized genes that may play a role in the antagonism to competing strains or specific symbiotic adaptations to the fish host. In conclusion, CFCEC proved to effectively allow the enrichment and further pure culture isolation of strains with probiotic potential.

Molecular and morphological evidence revalidates Acrobrycontarijae (Characiformes, Characidae) and shows hidden diversity.

We conducted a revision of the Neotropical genus Acrobrycon. A previous study synonymized the species, A.ipanquianus, distributed from the western portion of the Amazon River to the north-western region of the La Plata River Basin, and A.tarijae, with type locality in the Lipeo River in Bolivia. We revisited this result by collecting new morphometric, meristic, and genetic data (COI mitochondrial gene) for 24 individuals distributed along La Plata River Basin in Argentina, and discussed our results in the context of multiple biogeographic processes of isolation in that basin. Our results revealed a more complex history of diversification and geographic distribution across Acrobrycon species than previously suspected, probably associated with multiple biogeographic processes of isolation in La Plata River Basin. We present new evidence that led us to reconsider the validity of A.tarijae, which is distinguishable from A.ipanquianus by the number of vertebrae (37-39 vs. 41-42) and pleural ribs (12-13 vs. 14). These results were also supported by our molecular analyses that revealed a genetic divergence >4% between A.ipanquianus and A.tarijae. We also identified two main genetic clusters within A.tarijae: the first cluster consisted of specimens from the Bermejo, Pilcomayo, Itiyuro and Juramento river basins (northern Argentina); and the second cluster included specimens from the southernmost basins, such as the Salí River in Tucumán, Cuarto River in the province of Cordoba and the Quinto River in the province of San Luis. Our results suggest that the genetic structure observed in A.tarijae is the result of the type of drainage (endorheic vs. exorheic) and geographical distance.

Karyotype description and comparative chromosomal mapping of rDNA and U2 snDNA sequences in Eigenmannialimbata and E.microstoma (Teleostei, Gymnotiformes, Sternopygidae).

The genus Eigenmannia Jordan et Evermann,1896 includes electric fishes endemic to the Neotropical region with extensive karyotype variability and occurrence of different sex chromosome systems, however, cytogenetic studies within this group are restricted to few species. Here, we describe the karyotypes of Eigenmannialimbata (Schreiner et Miranda Ribeiro, 1903) and E.microstoma (Reinhardt, 1852) and the chromosomal locations of 5S and 18S rDNAs (ribosomal RNA genes) and U2 snDNA (small nuclear RNA gene). Among them, 18S rDNA sites were situated in only one chromosomal pair in both species, and co-localized with 5S rDNA in E.microstoma. On the other hand, 5S rDNA and U2 snRNA sites were observed on several chromosomes, with variation in the number of sites between species under study. These two repetitive DNAs were observed co-localized in one chromosomal pair in E.limbata and in four pairs in E.microstoma. Our study shows a new case of association of these two types of repetitive DNA in the genome of Gymnotiformes.

Distribution and Accumulation of Trace Elements in Organs of Juvenile Fishes from a Freshwater System (Paraná River, South America).

The concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (TE) in four juvenile fishes (Acestrorhynchus pantaneiro, Salminus brasiliensis, Brycon orbignyanus, and Megaleporinus obtusidens) and associated sediment water from the Lower Paraná River were measured. For muscle, gills, and liver fishes, the TE accumulation in the muscle, gills, and liver was evaluated. The TE concentration was measured by quadrupolar inductively coupled plasma mass spectrometry (Q-ICP-MS). Cadmium (0.25 ± 0.07 µg L-1), Cu (3.00 ± 1.44 µg L-1), Fe (612 ± 69 µg L-1), and Pb (1.92 ± 1.20 µg L-1) in water and As (4.1-6.9 µg g-1), Cr (20.1-31.4 µg g-1), Cu (10.7-19.2 µg g-1), Mn (351.3-482.2 µg g-1), and Ni (24.5 ± 10.9 µg g-1) in sediments exceeded the guide values for the conservation of aquatic life. In general, muscle of omnivorous species (B. orbignyanus and M. obtusidens) showed higher values of elements than those of carnivorous species (A. pantaneiro and S. brasiliensis). However, TE concentrations varied with fish species and organs. Independently of the examined species, the highest concentrations of Cr and Pb were in the muscle and gills, respectively. Cadmium, Cu, and Fe concentrations were higher in the liver than in gills and muscle in all four fish species. These results were consistent with the tissue selectivity index analyzed. For the four species, major essential elements showed the highest accumulation. However, the accumulation of toxic elements in omnivorous fish was higher than in carnivorous fish. The individual pollution load index indicated that sediment was very polluted with As and Pb, but based on the combined ecological indexes, low elemental sediment pollution in the Espinillo Lake was revealed.

Fishes from the Colombian Amazonia region: species composition from the river systems within the rainforest biome / Peces de la región de la Amazonía Colombiana: composición de especies de los sistemas fluviales del bioma de selva húmeda

Abstract The Colombian Amazon region is part of the Neotropical rainforest (humid forest biome) covering an area of 483,163 km2 and includes tributaries of both the Amazon and Orinoco River basins. The aquatic ecosystems found there include: rivers and alluvial plains originating in Andean headwaters, on eroded soils of tropical forests in the lowlands, and Guiana Shield formations, comprising a dense fluvial drainage network in the lowlands, with Paleogene/Neogene geological formations (terra firme streams in higher places that don't usually flood) and Paleozoic (shield streams); and Andean and Guiana Shield streams above 200-250 m a.s.l. We present here an exhaustive compilation of published information, supported by fish collections, consisting of a list of 1104 species distributed in 375 genera, 53 families, and 16 orders. We include occurrence data of these species in each sub-basin. The presence/absence species matrix was analyzed using a dendrogram and non-metric multidimensional scaling (NMDS) analysis to identify patterns of similarity between basins and sub-basins. We evaluated species composition between basins and among the different geological origins using PERMANOVA. The dendrogram shows co-occurrences of 404 species in the two basins. It also shows two clear groupings of the sub-basins of the Amazon (except Guainía-Negro drainages) and those of the Orinoco. Within the Amazon Basin, there are two nodes according to the geological origin: systems of Andean origin and those of the lowlands. The dendrogram results are consistent with the NMDS analysis, which shows a clear grouping according to the connectivity of the basins; the Guainía-Negro is included in the Amazon basin. Species distribution patterns were supported by the PERMANOVA, and differed significantly between basins (F = 4.3, R = 0.26, P = 0.003) and geological origin (F = 3.6, R = 0.23, P = 0.003). The number of species in this study represents almost a fifth of the ichthyofauna of the Neotropics and about a third of that of the Amazon River basin; clearly supporting Colombia's status among the countries with the greatest diversity of freshwater fish species of the planet. We include here a significant number of new records (75 spp), provide a first approximation of the distribution patterns, and a framework for future biogeographical studies.

Resumo La región de la Amazonía colombiana hace parte del bosque húmero neotropical (bioma de selva húmeda) abarcando un área de 483.163 km2 e incluye afluentes de las cuencas del Amazonas y Orinoco. Los ecosistemas acuáticos encontrados allí incluyen: ríos y llanuras aluviales, originándose en cabeceras andinas, en suelos erosionados de bosques tropicales en tierras bajas y en formaciones de escudos; conformando una densa red fluvial en tierras bajas con formaciones geológicas paleógenas-neógenas (arroyos de terra firme en sitios elevados que usualmente no se inundan) y paleozoicas (arroyos de escudo); y arroyos andinos y del escudo Guayanés por encima de 200-250 m s.n.m. Presentamos aquí una recopilación exhaustiva de información publicada, sustentada por colecciones ictiológicas, consistiendo en una lista de 1104 especies distribuidas en 375 géneros, 53 familias y 16 órdenes. Incluimos datos de estas especies en cada subcuenca. La matriz de presencia/ausencia de especies fue analizada usando un dendrograma y un análisis de escalamiento multidimensional no métrico (NMDS) para identificar patrones de similitud entre cuencas y subcuencas. Se evaluó la composición de especies entre cuencas y entre los diferentes orígenes geológicos usando PERMANOVA. El dendrograma refleja coocurrencia de 404 especies en las dos cuencas. También muestra dos agrupaciones claras de las subcuencas del Amazonas (excepto Guainía-Negro) y las del Orinoco. Dentro de la cuenca amazónica existen dos nodos según el origen geológico: los sistemas de origen andino y los de tierras bajas. Los resultados del dendrograma son consistentes con el análisis NMDS, el cual muestra una clara agrupación según la conectividad de las cuencas; el Guainía-Negro está incluido en la cuenca del Amazonas. Los patrones de distribución de especies fueron respaldados por el PERMANOVA y difirieron significativamente entre cuencas (F = 4.3, R = 0.26, P = 0.003) y origen geológico (F = 3.6, R = 0.23, P = 0.003). El número de especies en este estudio representa casi la quinta parte de la ictiofauna del Neotrópico y alrededor de un tercio de la de la cuenca del río Amazonas; soportando el estatus de Colombia entre los países con mayor diversidad de especies de peces de agua dulce del planeta. Incluimos aquí un número importante de nuevos registros (75 spp), brindamos una aproximación de los patrones de distribución y un marco para futuros estudios biogeográficos.

Divergence times of the Rhoadsia clade (Characiformes: Characidae)

The family Characidae is the most diverse group of fishes in the Neotropics with challenging systematics. The three genera Carlana, Parastremma, and Rhoadsia, formerly considered the subfamily Rhoadsiinae, are now included in the subfamily Stethaprioninae. Previous phylogenetic analyses did not include all genera of Rhoadsiinae, specifically Parastremma. Here, we estimated the phylogenetic relationships and divergence times of the genera of Rhoadsiinae (the Rhoadsia clade) relative to the most representative genera of the Characidae. We used six molecular markers from the mitochondrial and nuclear genome to estimate the phylogeny and divergence times. We confirmed the monophyly of the Rhoadsia clade. Furthermore, we estimated that the Central American genus Carlana and the western Colombian genus Parastremma diverged approximately 13 Mya (95% HPD 8.36­18.11), consistent with the early-closure estimates of the Isthmus of Panama (~15 Mya). The genus Rhoadsia, endemic to Western Ecuador and Northern Peru, was estimated to originate at around 20 Mya (95% HPD 14.35­25.43), consistent with the Andean uplift (~20 Mya).(AU)

La familia Characidae es el grupo más diverso de peces en el Neotrópico con una sistemática compleja. Los tres géneros Carlana, Parastremma y Rhoadsia, antes considerados en la subfamilia Rhoadsiinae, ahora se consideran dentro de la subfamilia Stethaprioninae. Los análisis filogenéticos publicados no incluyen todos los géneros de Rhoadsiinae, específicamente Parastremma. Aquí, estimamos las relaciones filogenéticas y los tiempos de divergencia de los géneros de Rhoadsiinae (el clado Rhoadsia) en relación con los géneros más representativos de Characidae. Utilizamos seis marcadores moleculares del genoma mitocondrial y nuclear para estimar la filogenia y el tiempo de divergencia. Confirmamos la monofilia del clado Rhoadsia. Además, estimamos que el género centroamericano Carlana y el género colombiano occidental Parastremma divergieron aproximadamente hace 13 millones de años (95% HPD 8.36­18.11), lo que es consistente con recientes estimaciones del cierre del Istmo de Panamá (~15 millones de años). Se estimó que el género Rhoadsia, endémico del oeste de Ecuador y el norte de Perú, se originó hace alrededor de 20 millones de años (95% HPD 14.35­25.43), consistente con el levantamiento de los Andes (~20 millones de años).(AU)