ABSTRACT
The Neotropical monophyletic catfish genus Harttia represents an excellent model to study karyotype and sex chromosome evolution in teleosts. Its species split into three phylogenetic clades distributed along the Brazilian territory and they differ widely in karyotype traits, including the presence of standard or multiple sex chromosome systems in some members. Here, we investigate the chromosomal rearrangements and associated synteny blocks involved in the origin of a multiple X1X2Y sex chromosome system present in three out of six sampled Amazonian-clade species. Using 5S and 18S ribosomal DNA fluorescence in situ hybridization and whole chromosome painting with probes corresponding to X1 and X2 chromosomes of X1X2Y system from H. punctata, we confirm previous assumptions that X1X2Y sex chromosome systems of H. punctata, H. duriventris and H. villasboas represent the same linkage groups which also form the putative XY sex chromosomes of H. rondoni. The shared homeology between X1X2Y sex chromosomes suggests they might have originated once in the common ancestor of these closely related species. A joint arrangement of mapped H. punctata X1 and X2 sex chromosomes in early diverging species of different Harttia clades suggests that the X1X2Y sex chromosome system may have formed through an X chromosome fission rather than previously proposed Y-autosome fusion.
Subject(s)
Catfishes , Animals , Catfishes/genetics , In Situ Hybridization, Fluorescence , Phylogeny , Sex Chromosomes/genetics , Y ChromosomeABSTRACT
The remarkable fish biodiversity encompasses also great sex chromosome variability. Harttia catfish belong to Neotropical models for karyotype and sex chromosome research. Some species possess one of the three male-heterogametic sex chromosome systems, XY, X1X2Y or XY1Y2, while other members of the genus have yet uncharacterized modes of sex determination. Particularly the XY1Y2 multiple sex chromosome system shows a relatively low incidence among vertebrates, and it has not been yet thoroughly investigated. Previous research suggested two independent X-autosome fusions in Harttia which led to the emergence of XY1Y2 sex chromosome system in three of its species. In this study, we investigated evolutionary trajectories of synteny blocks involved in this XY1Y2 system by probing six Harttia species with whole chromosome painting (WCP) probes derived from the X (HCA-X) and the chromosome 9 (HCA-9) of H. carvalhoi. We found that both painting probes hybridize to two distinct chromosome pairs in Amazonian species, whereas the HCA-9 probe paints three chromosome pairs in H. guianensis, endemic to Guyanese drainages. These findings demonstrate distinct evolutionary fates of mapped synteny blocks and thereby elevated karyotype dynamics in Harttia among the three evolutionary clades.
ABSTRACT
Ituglanis amphipotamus, new species, is distinguished from all congeners by the combination of the following characters: anterior cranial fontanel present, i,5 pectoral-fin rays, nasal canal and antorbital segment of infraorbital canal absent, five or six pairs of ribs, 39 post-Weberian vertebrae. It can be further distinguished from the sympatric I. proops by the size of the interopercular patch of odontodes. The new species is described from the Rio Ribeira de Iguape and the upper Rio Tietê basins in the southeastern region of Brazil. Comments on the biogeography of the new taxa and putative relationships with its congeners are presented. [Zoobank: urn:lsid:zoobank.org:act:AC2F3365-92C0-4444-AC89-9546365158EC].
Subject(s)
Catfishes , Animals , Brazil , Ribs , Rivers , SympatryABSTRACT
Most species of the genus Harttia inhabits the headwaters of small tributaries, but some species are restricted to the main channel of some rivers. This feature, combined with limited dispersal ability, leads to the formation of small isolated populations with reduced gene flow. Currently, there are 23 taxonomically defined and recognized species, and 17 of these are found in Brazil, distributed in several hydrographic basins. Despite this diversity, few chromosomal data for the species belonging to this genus are found in the literature. Thus, this study analyzed, by classical and molecular cytogenetics methodologies, the chromosomal diversity of this genus, to discuss the processes that are involved in the evolution and karyotype differentiation of the species of the group. Seven species of Harttia were analyzed: H. kronei, H. longipinna, H. gracilis, H. punctata, H. loricariformis, H. torrenticola, and H. carvalhoi. The chromosomal diversity found in these species includes different diploid and fundamental numbers, distinct distribution of several repetitive sequences, the presence of supernumerary chromosomes in H. longipinna and multiple sex chromosome systems of the type XX/XY1Y2 in H. carvalhoi and X1X1X2X2/X1X2Y in H. punctata. Lastly, our data highlight the genus Harttia as an excellent model for evolutionary studies.
Subject(s)
Biological Evolution , Catfishes/genetics , Genetic Variation , Karyotype , Animals , Carrier Proteins , Cytoskeletal Proteins , Female , Intracellular Signaling Peptides and Proteins , Male , Sex Chromosomes , Species SpecificityABSTRACT
A new species of Harttia, tribe Harttiini, is described from tributaries of upper portions of rio Paraná drainage. The new species, the smallest known species of the genus, attaining up to 74.0 mm of standard length, can be distinguished from its congeners by the combination of the following characters: abdomen completely covered by plates, a single preanal plate, plates of the gular area in broad contact with the canal plate. Harttia absaberi is the second species of the genus known from the upper portion of rio Paraná drainage.
Uma espécie nova de Harttia, tribo Harttiini, é descrita dos tributários da porção superior da drenagem do rio Paraná. A espécie nova, a menor espécie conhecida do gênero, alcançando até 74,0 mm de comprimento padrão, pode ser diferenciada de suas congêneres pela combinação dos seguintes caracteres: abdômen completamente coberto por placas ósseas, uma única placa preanal, placas da região gular em contato amplo com a placa portadora de canal. Harttia absaberi é a segunda espécie do gênero conhecida da porção superior da drenagem do rio Paraná.
Subject(s)
Animals , Rivers , Species Specificity , FishesABSTRACT
As espécies de peixes de água doce encontradas no estado de São Paulo distribuem-se entre quatro bacias hidrográficas principais: Alto Paraná, Paraíba do Sul, Ribeira de Iguape e um conjunto de pequenas drenagens costeiras que desembocam diretamente no oceano Atlântico. Como estas bacias drenam áreas com diferentes tipos de vegetação, solos, etc., cada uma tem uma composição de espécies diferente. No Alto Paraná, o grande Rio Paraná e alguns de seus maiores afluentes (Tietê, Paranapanema e Grande) possuem espécies de grande porte que sustentam a pesca comercial e de subsistência, mas 70 a 80% da ictiofauna é composta por espécies de pequeno porte de pequenos riachos, incluindo os de cabeceira, onde muitas são endêmicas. O inventário da ictiofauna foi incrementado através de três projetos de pesquisa apoiados pelo programa BIOTA/FAPESP, mas ainda resta muito trabalho de coleta e descrição de novas espécies de áreas pouco exploradas, como calhas de rios, regiões de cabeceiras, alagadiços em áreas marginais de reservatórios e lagos. A ictiofauna do Estado de São Paulo tem sofrido da ação deletéria de poluição, desmatamento, esgotos urbanos e construção de reservatórios para produção de energia elétrica, etc., de tal forma que atualmente 66 espécies são consideradas ameaçadas em vários níveis, de acordo com os critérios da "International Union for Conservation of Nature and Natural Resources" (IUCN).
The fish species living in the freshwaters of the São Paulo state (393) are distributed among four major river basins: upper Paraná, Paraíba do Sul, Ribeira de Iguape and a set of small coastal drainages flowing directly into the Atlantic Ocean. Since these river basins drain areas with distinct vegetation types, soils, etc., each one has a different species composition. In the Upper Paraná the large Rio Paraná and some of its large tributaries (Tietê, Paranapanema, and Grande) contain large species that support commercial fisheries, however, 70 to 80% of the ichthyofauna is composed by small species found in small streams, including those in headwaters where many are endemic. The inventory of the ichthyofauna greatly benefited from three research projects supported by the BIOTA/FAPESP program, but much work remains to be done to collect and describe new species from areas such as deep channels, headwaters and marginal and swampy áreas around ponds and man-made lakes and reservoirs. The ichthyofauna of the São Paulo State has suffered from deforestation, sewage, damming of rivers for construction of power plants, urbanization, etc., so that 66 species are currently considered threatened at various levels according to the criteria of the International Union for Conservation of Nature and Natural Resources (IUCN).
ABSTRACT
É apresentada uma síntese sobre os peixes do Alto Paraná, com base em dados de coleções, dados de literatura e novas coletas. Trezentas e dez espécies, de 11 ordens e 38 famílias, são referidas para a drenagem, aumentando significativamente números anteriores. Dentre as espécies da área, 236 (76,1 por cento) são autóctones, 67 (21,6 por cento) alóctones e sete (2,3 por cento) exóticas. As principais causas de ocorrência de espécies não nativas (alóctones e exóticas) foram a dispersão a partir do baixo Paraná, após a construção do Reservatório de Itaipu e o escape de pisciculturas. A maior parte das espécies referidas (65 por cento) tem porte pequeno, sendo menor que 21 cm de comprimento; dentre essas, a maioria ocorre apenas em riachos e cabeceiras. Apesar da ictiofauna do Alto Paraná ser uma das melhor conhecidas e mais estudadas, o número de espécies descritas ou referidas para a área tem crescido exponencialmente, o que indica que a riqueza apresentada está longe de representar a realidade. De fato, várias novas espécies têm sido descritas nos últimos anos e cerca de 50 novas espécies, já reconhecidas, estão em fase de descrição. A melhoria no conhecimento sobre a ictiofauna do Alto Paraná é proporcional ao número de pesquisadores envolvidos em estudos na bacia e reflete, de modo inequívoco, iniciativas recentes que têm estimulado e incrementado pesquisas taxonômicas, facilitado o acesso ao material depositado em coleções científicas e aumentado as coletas em áreas e ambientes pouco amostrados. Entretanto, mantido o ritmo de descrições de novas espécies ocorrido até agora nessa última década, as 50 novas espécies já reconhecidas estariam descritas apenas dentro de dez anos, um tempo demasiadamente longo. Por essa razão é muito importante que a comunidade científica e os órgãos de fomento encontrem e viabilizem iniciativas de modo a aumentar esse ritmo de descrições de novos táxons e disponibilizar esses novos nomes mais rapidamente.
A synthesis concerning fishes from Upper Paraná River basin is presented, based on data from fish-collections, literature, and new field samples. Three hundred and ten species, pertaining to 11 orders and 38 families, are referred to the drainage, elevating anterior estimates. Concerning total species, 236 (76.1 percent) are autochthonous, 67 (21.6 percent) are allochthonous, and seven (2.3 percent) are exotic. Principal causes of occurrence of non-native species are: a) dispersal from the Lower Paraná, after the construction of Itaipu dam, and b) escapes from aquaculture farms. Most species (65 percent) are small-sized, having less than 21 cm of length, and the great majority occurs only in headwaters and small streams. One of the best known and most studied in Brazil, Upper Paraná ichthyofauna richness is far from reaching actual numbers, considering the exponential elevation of species presented herein. Indeed, in the last years various new species have been described and around 50 other species, already recognized as new, are now under description. The improvement on the knowledge about Upper Paraná ichthyofauna is proportional to the number of researchers involved with studies in the area and, unequivocally, reflects recent initiatives stimulating and incrementing taxonomic research, and also improving access to fish collections and to poor or never-sampled areas. However, if we are going to maintain the number of species descriptions per year of last decade, the 50 new species already recognized, will be described only in the next ten years, a period too long. In consequence it is very important that scientific community and grant agencies find and offer initiatives in order to elevate the number of new taxa descriptions per year.
