Resumo Hypostomus está distribuído por bacias da América Central e do Sul, com grande diversidade de espécies com conflitos taxonômicos. Desta forma, a integração de técnicas auxiliares contribui para a compreensão da sistemática e filogenia do grupo. Assim, este estudo teve como objetivo investigar Hypostomus cochliodon e H. boulengeri do riacho Onça (bacia do rio Paraguai) por meio de técnicas aloenzimáticas e citogenéticas. As análises citogenéticas em H. boulengeri mostraram número cromossômico igual a 2n = 68 (14m+14sm+18st+22a), sistema de NOR múltiplo revelado por Ag-NOR e 18S-FISH, um polimorfismo de heterocromatina em acrocêntricos e a presença de microcromossomos Bs. Hypostomus cochliodon mostrou um número diploide de 64 cromossomos (16m+26sm+14st+8a); apesar do sistema de NOR simples, alguns indivíduos apresentaram NOR em ambos os telômeros detectados por Ag-NOR e 18S-FISH. Uma isozima identificou dois loci diagnósticos (Idh-A and Gdh-A) entre as duas espécies e múltiplos loci com alelos únicos em H. boulengeri. A variabilidade genética indicada pela heterozigosidade média (He) foi de 0,2461 e 0,0309 em H. boulengeri e H. cochliodon, respectivamente. Assim, este estudo relata os primeiros dados citogenéticos para H. boulengeri e os primeiros dados isoenzimáticos para H. boulengeri e H. cochliodon. As duas espécies apresentaram evidentes diferenças citogenéticas e isoenzimáticas com a obtenção de marcadores genéticos exclusivos fornecendo suporte para futuros estudos evolutivos no grupo. Sul taxonômicos forma grupo Assim H bacia Paraguai n 6 14m+14sm+18st+22a, 14m14sm18st22a msmsta 14m+14sm+18st+22a , 14m 14sm 18st 22a m sm st (14m+14sm+18st+22a) AgNOR Ag 18SFISH, 18SFISH SFISH 18S FISH, FISH S 18S-FISH Bs 16m+26sm+14st+8a 16m26sm14st8a 16m 26sm 14st 8a (16m+26sm+14st+8a) simples 18SFISH. FISH. IdhA Idh GdhA Gdh Gdh-A He (He 02461 0 2461 0,246 00309 0309 0,030 respectivamente (14m+14sm+18st+22a (16m+26sm+14st+8a 0246 246 0,24 0030 030 0,03 024 24 0,2 003 03 0,0 02 2 0, 00

Abstract Hypostomus is distributed by Central and South America basins, with diverse species with taxonomic conflicts. This way, the integration of auxiliary techniques contributes to understanding the systematics and phylogeny of the group. Thus, this study aimed to investigate the Hypostomus cochliodon and H. boulengeri from the Onça stream (Paraguai River basin) by allozyme and cytogenetic techniques. Hypostomus boulengeri showed a diploid number of 68 chromosomes (14m+14sm+18st+22a), multiple NOR revealed by Ag-NOR and 18S rDNA FISH, a polymorphism of heterochromatin in acrocentrics and the presence of B microchromosome. Hypostomus cochliodon showed a diploid number of 64 chromosomes (16m+26sm+14st+8a); despite the single NOR, some individuals showed NOR in both telomeres detected by Ag-NOR and 18S rDNA FISH. Isozyme identified two diagnostic loci (Idh-A and Gdh-A) between the two species and multiple loci with unique alleles in H. boulengeri. The genetic variability indicated by the mean heterozygosity (He) was 0.2461 and 0.0309 in H. boulengeri and H. cochliodon,respectively.Thus, this study reports the first cytogenetic data for H. boulengeri and the first isozymatic data for H. boulengeri and H. cochliodon. The two species presented evident cytogenetic and isoenzymatic differences with the obtaining of exclusive genetic markers providing support for future evolutionary studies in the group. basins conflicts way group Thus H Paraguai basin 6 14m+14sm+18st+22a, 14m14sm18st22a msmsta 14m+14sm+18st+22a , 14m 14sm 18st 22a m sm st (14m+14sm+18st+22a) AgNOR Ag S FISH microchromosome 16m+26sm+14st+8a 16m26sm14st8a 16m 26sm 14st 8a (16m+26sm+14st+8a) IdhA Idh A GdhA Gdh Gdh-A He (He 02461 0 2461 0.246 00309 0309 0.030 cochliodonrespectivelyThus respectively cochliodon,respectively.Thus (14m+14sm+18st+22a (16m+26sm+14st+8a 0246 246 0.24 0030 030 0.03 024 24 0.2 003 03 0.0 02 2 0. 00

Three Brazilian populations of the armored catfish Hypostomus regani (Ihering, 1905) were sampled, one from the Corumbá Reservoir in Goiás state, another from the Itaipu Reservoir in Paraná state and a third from the Manso Reservoir in Mato Grosso state. Allozyme electrophoresis was used to establish the genetic structure of the species, with the analysis of liver, heart and muscles tissues allowing the scoring of 25 loci from 14 enzymatic systems. Although no diagnostic loci were found, some exclusive rare alleles were recorded for the three populations. The genetically most similar populations were those from Corumbá and Itaipu, and the most distant were the populations from Manso and Corumbá. The allozyme data showed three structured populations belonging to the same species H. regani (F ST = 0.173).

Hypostomus strigaticeps and two morphotypes of Hypostomus were collected from Ribeirão Maringá, a small tributary of the Rio Pirapó, an effluent of the upper Rio Paraná. The three populations were analyzed by allozyme electrophoresis that allowed the scoring of 25 loci from 14 enzyme systems. Heterozygosity values (He) were 0.028 in H. strigaticeps, 0.027 in Hypostomus sp. 1 and zero in Hypostomus sp. 2. Several diagnostic loci and fixed differences were observed for each population at loci Acp-A, Gcdh-A and Mdhp-A. Thus, all populations were genetically distinct, although there were many common alleles. The unbiased genetic identities of Nei (I) were estimated as 0.780 for Hypostomus sp. 1 and H. strigaticeps, 0.357 for H. strigaticeps and Hypostomus sp. 2 and 0.322 for Hypostomus sp. 1 and Hypostomus sp. 2. The data indicate that the two morphotypes are distinct species from Hypostomus strigaticeps.