Cytogenetic analysis of three catfish species of the family Pseudopimelodidae (Teleostei, Siluriformes)

Abstract

Cytogenetic analyses performed in Cephalosilurus apurensis, Microglanis aff. cottoides and Pseudopimelodus bufonius revealed that the three species have 2n = 54 chromosomes: C. apurensis presented six metacentric (M), 28 submetacentric (SM), 14 subtelolocentric (ST), and six acrocentric (A) chromosomes, while M. aff. cottoides showed 10M, 32SM, 10ST and 2A, and P. bufonius had 12M, 30SM and 12ST. The nucleolus organizer regions (NORs) were present on the short arm of a middle-sized ST pair, identified as pair 19, in C. apurensis NORs were found on the short arm of a middle-sized ST (pair 23) and on the long arm of a middle-sized ST (pair 22) in M. aff. cotttoides and on the short arm of three middle-sized ST pairs, identified as pairs 9, 10 and 11, in P. bufonius. C-banding revealed a very small amount of constitutive heterochromatin in the chromosomes of all species, including the NORs. The occurrence of 2n = 54 in all species of the family Pseudopimelodidae and its absence among species of the closely related Pimelodidae and Heptapteridae may be important in identifying Pseudopimelodidae species.

First cytogenetic studies of the genus Heptapterus (Actinopterygii, Siluriformes): karyotype differentiation and review of cytogenetic data on the Heptapteridae family

“…In addition, Lundberg et al (1991) suggested a sister group relationship between the Heptapteridae and Pseudopimelodidae families based on the structure of the lower lip. Martinez et al (2008) worked with three species of Pseudopimelodidae and following a comparison of other published studies; found that the presence of 54 chromosomes may be an important characteristic in differentiating the species of this family from the species of Heptapteridae and Pimelodidae, a hypothesis that cannot be applied based on this study.…”

“…Although the number of chromosomes found in H. mustelinus is within the variation observed in Heptapteridae (42-58 chromosomes), the diploid number of 54 chromosomes found in this study differs from all data on the species of Heptapteridae analysed to date. This diploid number, however, has been found in species of the Pseudopimelodidae family (Vissotto et al, 1999a;Marques et al, 2008;Martinez et al, 2008), which, just as Heptapteridae, was already considered a subfamily in Pimelodidae (Pinna, 1998). In addition, Lundberg et al (1991) suggested a sister group relationship between the Heptapteridae and Pseudopimelodidae families based on the structure of the lower lip.…”

Cytogenetic Trends in Two Families of the Neotropical Catfishes: Heptapteridae and Pseudopimelodidae (Siluriformes)

“…Some of these cytogenetic differences were previously reported by other authors and could be attributed to inversions or translocations with consequences in the karyotypic formula. 12,30,36 The diverse karyotypic characterization could be related more to technical artifacts than real differences. However, these variations should also be considered to show the importance of a more detailed analysis of the characterization of these species by taxonomic studies, besides the fact that M. cibelae of the present work was collected in the type-locality of the description of this species.…”

“…Probably, the most likely NOR phenotype in M. cottoides is the short-arm (par 24) terminal region that is shared in the analyzed populations of this species. 12,36 Inversion and translocation events may explain NOR in the terminal region of the long arm in M. cottoides of the Antas river.…”

Estudos cromossômicos e moleculares em Rhamdia (Pisces, Siluriformes, Heptapteridae): análise de relações evolutivas

“…Mais tarde, estes grupos foram elevados à categoria de família (Nelson, 2006;Ferraris, 2007). Essa divisão em três famílias é corroborada pelos dados citogenéticos, uma vez que cada família possui um número diplóide predominante característico, sendo esses 2n = 54, 56 e 58 cromossomos, em Pseudopimelodidae, Pimelodidae e Heptapteridae, respectivamente (Swarça et al, 2000;Garcia, 2005;Martinez et al, 2008a).…”