Vladimir Margarido

• Western Paraná State University

Disagreements in molecular and morphological analyzes have generated conflicts about the correct allocation of Hemiancistrus fuliginosus in Hypostominae. In this study, cytogenetics analyzes in four populations of H. fuliginosus from tributaries of the Uruguai Riverrevealed 2n = 56 chromosomes (30m + 18sm + 6st + 2a) for all populations. Nucleolar...

Centromochlus heckelii has the lowest diploid chromosome number (2n = 46) and the only described heteromorphic sex chromosome system in Auchenipteridae. This study presents a population of C. heckelii from the Central Amazon basin with subtle variations in the karyotype composition and a variant W chromosome with distinct morphology and increased C...

The Hoplias malabaricus group comprises seven described species, including seven karyomorphs for H. malabaricus. However, the relationship between morphological and chromosomal data within the group remains unresolved. Most studies on the Hoplias malabaricus group from the Iguazu River ecoregion have primarily focused on its upper and middle sectio...

The genus Tetranematichthys has only three species, and none of them have undergone cytogenetic analyses. Therefore, this study brings for the first time the analysis of Tetranematichthys wallacei, collected from the Igarapé Apaú, Guamá River basin, municipality of Castanhal, Pará State, Brazil. The diploid number found was 52 chromosomes (32m+18sm...

Objective: Megaleporinus macrocephalus, a native species from the Neotropical region, was used as a model to evaluate the effects of pyriproxyfen on larval development at a dose that could be found in the environment. Theoretical Framework: Pyriproxyfen is a compound used to control of the mosquito Aedes aegypti, vector of Neotropical diseases. In...

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 geneti...

Using integrative tools can be effective for species identification, especially in complex groups like Astyanax. Astyanax bimaculatus group is composed of six valid species, including A. lacustris. "A. altiparanae", "A. asuncionensis", and "A. jacuhiensis" are considered as junior synonyms of A. lacustris. Seeking to test the operational taxonomic...

Comprising more than 100 species, Crenicichlina encompasses 20% of the taxonomic diversity of Neotropical cichlids and is widely distributed throughout Brazilian watersheds. A new hypothesis about the phylogeny of pike cichlids has recently been proposed, based on morphological and molecular characters, and new genera were created. We analyzed 18 s...

Trachelyopterus Valenciennes 1840 species exhibit striking morphological and cytogenetic similarities, leading to persistent taxonomic challenges. This research focuses on Trachelyopterus galeatus Linnaeus 1766 and Trachelyopterus porosus Eigenmann & Eigenmann 1888, both widely distributed throughout South America and often sympatric, facilitating...

The fishes of the Doradidae family constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and sister group to all other thorny catfishes, and includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, with several putative species yet to be described,...

The fishes of the Doradidae family constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and sister group to all other thorny catfishes, and includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, with several putative species yet to be described,...

The scattered distribution pattern of microsatellites is a challenging problem in fish cytogenetics. This type of array hinders the identification of useful patterns and the comparison between species, often resulting in over-limited interpretations that only label it as "scattered" or "widely distributed". However, several studies have shown that...

Psalidodon fasciatus is a complex of several fish species widely distributed in Brazilian hydrographic systems that share morphological characteristics and show a high taxonomic complexity and genetic variability. Cytogenetic and molecular analyses were carried out in populations from three Brazilian hydrographic basins, aiming to contribute to sys...

This study aimed to identify species of Astyanax bimaculatus group from four Itaipu Reservoir tributaries (Paraná River Basin) by cytogenetics and molecular markers (COI) to investigate the possible occurrence of cryptic diversity in part of this basin. The four populations showed only one karyotype formula and simple AgNORs. FISH with 18S rDNA pro...

Hypostomus is the most specious genus of Hypostominae, composed of several species with high intraspecific morphological and color pattern variation, making their identification a complex issue. One of the species with problematic identification is Hypostomus tietensis that was described from a single specimen, resulting in uncertainties about its...

Trachelyopterus is a Neotropical catfish genus with a controversial taxonomic history due to the morphological similarity among species. Cytogenetically, only classic techniques (Giemsa, C-band, and Ag-NOR), 18S rDNA, 5S rDNA, telomeric probes, and the microsatellite (GATA)n have been applied in some species of the genus. Therefore, through an inte...

Corydoras is the richest genus of Corydoradinae, and many of its species have not been identified to date. We characterized Corydoras carlae and Corydoras sp. by performing cytogenetic, morphometric, and molecular analyses to facilitate correct identification and species delimitation and contribute an understanding of the evolutionary process of th...

The aims of the study were: (i) evaluate the efficacy of using amphibian adipose tissue as a valid biomarker of water contaminated by pyriproxyfen; and (ii) verify the use of Lithobates catesbeianus in laboratory experiments as a potential bioindicator for bioaccumulation of pesticide in adipose tissue from amphibians. Adult frogs were exposed to d...

Fishes of the genus Gymnotus have been suggested as a good model for biogeo-graphic studies in the South American continent. In relation to heterochromatin, species of this genus have blocks preferably distributed in the centromeric region. The content of these regions has been shown to be variable, with description of transpos-able elements, pseud...

Basic and molecular cytogenetic techniques were carried out in 3 Neotropical region populations of catfishes, two of Trachelyopterus galeatus (one from the marshlands of Paraguay River basin and another from Lago Catalão, Amazon River basin) and one of Trachelyopterus porosus, a sympatric population to T. galeatus from the Amazon River basin. This...

The aim of this paper was to present the second case of B chromosomes in Auchenipteridae (Trachelyopterus sp.), and to test the hypothesis that the B chromosomes of this species and Parauchenipterus galeatus might have a common origin, since these two species have phylogenetic proximity. Both species have 58 chromosomes in the A complement, heteroc...

Doradinae (Siluriformes: Doradidae) is the most species-rich subfamily among thorny catfishes, encompassing over 77 valid species, found mainly in Amazon and Platina hydrographic basins. Here, we analyzed seven Doradinae species using combined methods (e.g., cytogenetic tools and Mesquite ancestral reconstruction software) in order to scrutinize th...

Farlowella is the second richest genus in Loricariinae, broadly distributed in freshwater streams and rivers of South America. In this article, we aimed to expand on the cytogenetic and molecular data available for two allopatric populations of Farlowella hahni. Both populations had diploid chromosome number 58, but with karyotype differences, indi...

Auchenipteridae is divided into subfamilies Centromochlinae and Auchenipterinae. Parauchenipterus is included in the latter and is subject of taxonomic discussions concerning its validation or synonymization with Trachelyopterus. Herein, three species from two hydrographic basins were cytogenetically analyzed: Parauchenipterus striatulus from Doce...

Background: One of the biggest challenges in chromosome biology is to understand the occurrence and complex genetics of the extra, non-essential karyotype elements, commonly known as supernumerary or B chromosomes (Bs). The non-Mendelian inheritance and non-pairing abilities of B chromosomes make them an interesting model for genomics studies, thu...

The present study provides new insight into the chromosomal diversification in Loricariinae. We analyzed nine species from different Brazilian hydrographic basins, using conventional and molecular cytogenetics methods, aiming to understand the karyotipic diversification, and contribute with cytotaxonomic markers in these group considered one of the...

Astyanax is a species-rich, non-monophyletic genus composed of several supraspecific taxa that are poorly delimited. The Astyanax fasciatus complex is one of these taxa and shows high taxonomic complexity. To elucidate the evolutionary history of the A. fasciatus complex from southern South America, we conducted cytogenetic, molecular and morpholog...

Cytogenetic data showed a variation in diploid chromosome number in the genus Hyphessobrycon ranging from 2n = 46 to 52, and studies involving repetitive DNA sequences are scarce in representatives of this genus. The purpose of this paper was the chromosomal mapping of repetitive sequences (rDNA, histone genes, U snDNA and microsatellites) and inve...

While most anurans have limited vagility and local fidelity, there are some exceptions. In the present study, we used Boana boans, a large treefrog found throughout most of the Amazon basin, as a model organism. We investigated the possible isolation of the B. boans demes located on opposite margins of the Juruena River and their population structu...

Astyanax is a species-rich, non-monophyletic genus composed of several supraspecific taxa that are poorly delimited. The Astyanax fasciatus complex is one of these taxa and shows high taxonomic complexity. To elucidate the evolutionary history of the A. fasciatus complex from southern South America, we conducted cytogenetic, molecular and morpholog...

Historically, there are divergences in the species allocation between Centromochlus and Tatia. This study aimed to generate the first cytogenetic data about Centromochlus and, by analyzing a population of Centromochlus heckelii from the Amazon River basin, to contribute as evidence to a historical taxonomic dilemma. Diploid number of 46 chromosomes...

Gymnotiformes fishes present a great variation in chromosome numbers. Sternopygidae species are either sex-homomorphic or sex-heteromorphic. This study reports a novel ZZ/ZW chromosome morphology type in Eigenmannia virescens collected from the upper Paraná River basin, which presented karyotype composed of 2n = 38 chromosomes, 6 metacentric (m), 1...

Wertheimerinae is a small subfamily of thorny catfish composed by two species found in eastern Brazilian coastal drainages: Wertheimeria maculata (found in Jequitinhonha-Pardo Rivers) and Kalyptodoras bahiensis (endangered species endemic from Paraguaçu River). According to molecular phylogenetic analysis, Franciscodoras marmoratus (endemic of São...

Bryconamericus is a highly diverse group of characid fishes, being cytogenetic a valuable tool for the delimitation of species. Bryconamericus aff. iheringii (Upper Uruguay/Lower Paraná), B. coeruleus (Upper Paraná), B. cf. ecai e B. cf. eigenmanni (Upper Uruguay) were studied cytogenetically, and presented 2n=52 chromosomes, with interpopulational...

Gymnorhamphichthys britskii is a Neotropical electric fish of family Rhamphichthyidae described from the Paraná-Paraguay system. This study reports the first karyotypic description of G. britskii collected from the upper Paraná river basin, which presented 2n=38 chromosomes, karyotype composed of 14 metacentric, 8 submetacentric, 2 subtelocentric a...

Hypostominae is the largest subfamily of Loricariidae, and is widely distributed throughout the Neotropic. In the present article, we analyze three Loricariidae species that were considered part of Hypostominae, from three different tribes, to discuss chromosome evolution in this fish group and to review the existent data for the subfamily. Rhinele...

Pimelodidae harbors several species and is widely distributed throughout the Neotropical region. Pimelodus is the genus with the largest number of species, however it is a polyphyletic group. Cytogenetic analyzes of the valid species still covers less than half of them. Herein, seven Pimelodus species from three Brazilian hydrographic systems were...

Knowledge of the fish species in river basins is among the minimum requirements for the management of water and fish resources. Therefore, the aim of this study was to update the fish species composition of the Piquiri River basin, upper Paraná River basin. Data were gathered from recent information published in specialized literature and records f...

Astyanax is a species-rich polyphyletic genus distributed between the southern United States and central Argentina. The genus contains groups of cryptic species, which are difficult to distinguish, and are sometimes identified wrongly. Basic and molecular cytogenetic analyses were run on Astyanax abramis and three junior synonyms of Astyanax lacust...

Doradidae has been a target of phylogenetic studies over the last few years, but chromosomal information about the family is still scarce. Therefore, new cytogenetic data are provided herein and they are correlated with phylogenetic proposals to contribute to the knowledge of chromosomal evolution within doradids. Cytogenetic studies were performed...

Anadoras é um pequeno gênero dentre os sete alocados na subfamília Astrodoradinae, o segundo maior grupo de Doradidae. Apenas duas espécies são formalmente reconhecidas: Anadoras grypus e Anadoras weddelli, sendo que uma espécie ainda não descrita ocorre no Alto Araguaia denominada Anadoras sp. “araguaia”. No presente estudo essas três espécies for...

Estudos citogenéticos e moleculares indicam ampla variabilidade cromossômica em Astyanax, principalmente dentro dos complexos de espécies. Tais fatores, somados a ampla distribuição geográfica, porte diminuto e semelhança morfológica, contribuem para a complexidade do grupo e dificultam a identificação e o estabelecimento de relações filogenéticas....

Bryconamericus é um dos gêneros mais numerosos de Characidae, com cerca de 60 espécies de porte reduzido, popularmente conhecidas como “lambaris”, e ampla diversidade nas drenagens atlânticas do continente americano. Apesar do elevado número de espécies, poucas foram estudadas citogeneticamente. Estudos citogenéticos em populações de Bryconamericus...

Dentre os loricarídeos, Rineloricaria tem destaque devido a elevada quantidade de espécies. Com ampla distribuição geográfica e grande diversidade de habitats, possuem alta complexidade taxonômica e citogenética, o que dificulta a compreensão da evolução do grupo. Este estudo buscou caracterizar citogeneticamente uma população de Rineloricaria zain...

The karyotype and chromosomal characteristics of Apteronotus albifrons and Apteronotus caudimaculosus collected from populations of two different large Brazilian river basins were analyzed by conventional and molecular cytogenetic techniques, to contribute to the differentiation and identification of the species in this genus. The diploid chromosom...

Karyotype and chromosomal characteristics of both minor and major rDNA of Sternopygus macrurus, a weakly electric South American fish, from two populations of the upper Paraná River basin, were investigated using conventional (Giemsa staining, silver staining, C-banding and base-specific fluorochromes) and molecular (fluorescent in situ hybridizati...

We provide cytogenetic data for the threatened species Gymnogeophagus setequedas, and the first record of that species collected in the Iguaçu River, within the Iguaçu National Park’s area of environmental preservation, which is an unexpected occurrence for that species. We verified a diploid number of 2n = 48 chromosomes (4sm + 24st + 20a) and the...

Karyotypes and other chromosomal markers as revealed by conventional and molecular cytogenetic protocols in four species of the catfish family Doradidae from the Araguaia-Tocantins river basin, namely Hassar wilderi, Leptodoras cataniae, Tenellus leporhinus and Tenellus trimaculatus were examined. All species had diploid chromosome number 2n = 58 a...

Corydoras Lacepède, 1803 is the most specious genus of Corydoradinae subfamily and many of its species are still unknown in relation molecular cytogenetic markers. However, the diploid number and karyotypic formula were recorded for many species of this group. In current study, we provided the first cytogenetic information of Corydoras carlae Nijss...

The karyotype and chromosomal characteristics of Trachydorasparaguayensis, a representative of the South American catfish family Doradidae, were analyzed by conventional (Giemsa staining, silver staining, C-banding) and molecular (FISH with rDNA and telomeric probes) cytogenetic techniques. The diploid chromosome number was 2n = 56, with 36 metacen...

The fish species Erythrinus erythrinus belongs to the family Erythrinidae (order Characiformes, superorder Teleostei) and is considered a species complex because of the considerable differences between the karyotypes of analyzed populations. Whereas some populations present a sex chromosome system with male heterogamety, others do not show differen...

The Iguazu river is a tributary of the left margin of the Paraná river, isolated from this basin about 22 million years ago with the appearance of the Iguazu Falls. The Iguazu river is characterized by high endemism due to two factors: its rugged topography and the old isolation caused by formation of the Iguazu Falls. This study analyzed cytogenet...

The karyotype of the Ancistrini catfish Ancistrus taunayi was analyzed by conventional (Giemsa staining, AgNOR staining and C-banding) and molecular cytogenetic (5S and 18S rDNA-FISH) methods. The diploid chromosome number was 2n = 50 (22 metacentrics + 10 submetacentrics + 10 subtelocentrics + 8 acrocentrics) for both sexes. A single NOR-bearing a...

The genetic diversity of the specimens of four natural populations of Arapaima from Araguaia-Tocantins basin was assessed within and among these stocks, using five primers for ISSR. COI (cytochrome c oxidase subunit I) partial sequences confirmed that the specimens belongs to Arapaima gigas. The ISSR provided 168 loci, of which 165 were polymorphic...

Karyotypes and chromosomal characteristics of both minor and major rDNAs in four fish species known popularly as "lambaris", namely Astyanax abramis (Jenyns, 1842), Astyanax asuncionensis Gery, 1972, Astyanax correntinus (Holmberg, 1891) and Astyanax sp. collected from downstream of the Iguassu Falls (Middle Parana River basin), preservation area o...

Hypostomus is a diverse group with unclear aspects regarding its biology, including the mechanisms that led to chromosome diversification within the group. Fluorescence in situ hybridization (FISH) with 5S and 18S rDNA probes was performed on ten Hypostomini species. Hypostomus faveolus, H. cochliodon, H. albopunctatus, H. aff. paulinus, and H. top...

Molecular genetic assessments that consider ecological information, in addition to endogamy levels, genetic diversity, and the genetic differentiation among species and populations, are particularly important for the conservation of biological diversity. Prime candidates for conservation genetic review are those subject to human use, including harv...

Abstract A cytogenetic analysis was performed on four populations of Hypostomus strigaticeps from the Paraná River basin, Brazil. Two populations were collected from the large channel river at the Itaipu reservoir area and the other two were from the upper stretches of tributaries of the Paraná River. All populations showed 2n=72 chromosomes (12m+1...

Erythrinidae include Neotropical teleost fish that are widely distributed in South America. Hoplias Gill, 1903 include two large groups: H. malabaricus Bloch, 1794 and H. lacerdae Miranda Ribeiro, 1908. Hoplias malabaricus is characterized by remarkable karyotype diversity, with some karyomorphs widely distributed geographically while others are mo...

B chromosomes are extra chromosomes from the normal chromosomal set, found in different organisms, highlighting their presence on the group of fishes. Callichthys callichthys from the upper Parana River has a diploid number of 56 chromosomes (26 m-sm + 30 st-a) for both sexes, with the presence of a sporadically acrocentric B chromosome. Moreover,...

Populations of Astyanax paranae, Astyanax fasciatus and Astyanax altiparanae collected from the Pindorama and Lopei streams (upper Paraná river basin, Brazil) were cytogenetically studied, checking for chromosomal differentiation and the evolutionary trend in the three species. Forty-eight chromosomes (8m + 20sm + 10st + 10a) were observed in both...

Populations of Astyanax paranae, Astyanax fasciatus and Astyanax altiparanae collected from the Pindorama and Lopei streams (upper Paraná river basin, Brazil) were cytogenetically studied, checking for chromosomal differentiation and the evolutionary trend in the three species. Forty-eight chromosomes (8m + 20sm + 10st + 10a) were observed in both...

Representing a reflection of anthropic activity, the level of xenobiotic compounds in aquatic ecosystems has increased in recent years, bringing severe damage to the environment. The present work reports the occurrence of malformation in gonads of Physalaemus cuvieri individuals from a population of Atlantic Forest in Southern Brazil. Twenty male s...

The Callichthyinae subfamily is composed of five genera with a small number of described species. Molecular cytogenetics studies show the scarcity of records for this subfamily. The aim of the present study was to employ cytogenetic parameters in the analysis of three species belonging to the subfamily Callichthyinae sampled from the Paraná River (...

Australoheros is represented by species of Cichlidae spread over different Brazilian river systems. Individuals of Australoheros angiru were collected in isolated lagoons at 950 m of altitude in a dividing plateau between the basins of the Iguassu River and the Uruguay River, located in the São Lourenço do Oeste region (Santa Catarina State), and s...

Harttia is a genus in the subfamily Loricariinae that accommodates fishes popularly known as armored catfishes. They show extensive karyotypic diversity regarding interspecific numerical/structural variation of the karyotypes, with the presence of the XX/XY1Y2 multiple sex chromosome system, as found in H. carvalhoi. In this context, this study aim...

The greatest diversity of anurans in the world is in Brazil and one of the major challenges is to reconcile the accelerated economic development with strategies that aim to maintain this diversity in forest fragments, often representing ESUs of some biomes. This study aimed to obtain data that will support conservation projects through the pioneeri...

Ageneiosus is the most widely distributed genus of the family Auchenipteridae among South American river basins. Although chromosome studies in the family are scarce, this genus has the largest number of analyzed species, with 2n = 54 to 56 chromosomes, differing from the rest of the family (2n = 58). This study aimed to analyze Ageneiosus inermis...

Auchenipteridae is divided in two subfamilies, Centromochlinae and Auchenipterinae. Centromochlinae has 31 valid species, from which 13 are included in the genus Tatia Miranda Ribeiro, 1911. Among these, Tatia jaracatia Pavanelli & Bifi, 2009 and Tatia neivai (Ihering, 1930) are the only two representative species from the Paraná-Paraguay basins. T...

The Neotropical fish Heptapterus mustelinus, collected in the Pindorama stream of the upper Paraná River basin (Brazil), was studied cytogenetically, verifying 54 chromosomes (26m + 18m + 4st + 6a). This diploid number has not been reported among the Heptapteridae that have been studied to date. Unlike most species of the family, there were multipl...

This study analyzed sequences of the control region of mitochondrial DNA (D-loop) in three populations of Parauchenipterus galeatus from the basins of the Paraná, São Francisco, and Piumhi rivers, of which the last river being a region that suffered transposition river. A fragment of 850 base pairs was obtained with a total of 65 polymorphic sites....

This study presents an adaptation of current methodologies for preparing mitotic chromosomes from fishes, optimized for use in the field. The high-quality preparations obtained using this modified methodology is suitable for subsequent chromosomal analysis. Importantly, this method is particularly useful when specimen collection sites are far from...

Hypostomus is a species-rich genus of fish with unclear systematics and phylogenetic relationships. Ten species of Hypostomus (H. albopunctatus, H. ancistroides, H. cochliodon, H. commersoni, H. faveolus, H. hermanni, H. aff. paulinus, H. regani, H. strigaticeps and H. topavae) were cytogenetically analyzed through Giemsa staining and silver nitrat...

The taxonomy of the family Parodontidae is confused, with many open questions regarding the most appropriate generic groupings. Studies on the organization, structure, composition, and in situ location of chromosomal features have led to consistent advances in the understanding of genome evolution. Among the species of Parodontidae, the consistent...

Neotropical fishes have a low rate of chromosome differentiation between sexes. The present study characterizes the first meiotic analysis of sex chromosomes in the order Gymnotiformes. Gymnotus pantanal - females had 40 chromosomes (14m/sm, 26st/a) and males had 39 chromosomes (15m/sm, 24st/a), with a fundamental number of 54 - showed a multiple s...

Physical mapping of 5S rDNA in 2 species of knifefishes, Gymnotuspantanal and G. paraguensis (Gymnotiformes), was performed using fluorescence in situ hybridization with a 5S rDNA probe. The 5S rDNA PCR product from the genomes of both species was also sequenced and aligned to determine non-transcribed spacer sequences (NTS). Both species under stu...

Color pattern is an important character in the systematics and alpha-taxonomy of electric fishes of the genus Gymnotus. This paper presents evidence of color variation in populations of G. pantanal found in the streams Jacutinga and Pinheirinho, in the upper Paraná River basin, southern Brazil. Color variations were corroborated for morphological a...

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotate...

Phylogenetic relationships and identification of species of the genus Hypostomus is still unclear. Considering this, cytogenetics may prove itself as an important tool in understanding the systematic of this genus. Reviews in Hypostomus indicate that the diploid number ranges from 54 to 84 chromosomes, and the increase in diploid number has been as...