Karotype Corydoras

[Walter]

Shimabukuro-Dias, Cristiane Kioko, Claudio Oliveira and Fausto Foresti (2004):
Karyotype variability in eleven species of the catfish genus Corydoras (Siluriformes: Callichthyidae) Ichthyological Exploration of Freshwaters, Volume 15 Number 2, p 135

The karyotype of 11 species of the callichthyid catfish genus Corydoras have been investigated using conventional Giemsa-staining, silver (Ag)- and C-banding to detect nucleolar organizer region (Ag-NOR) phenotypes and heterochromatin distribution, respectively. Diploid numbers and karyotypes were as follows: C. ehrhardti, 2n=44 (22M+22SM); C. nattereri, 2n=44 (18M+26SM); C. paleatus, 2n=44 (20M+24SM); C. cf. nijsseni, 2n=52 (32M+20SM); C. undulatus, 2n=52 (24M+14SM+12ST+2A); C. zygatus, 2n=56 (18M+20SM+10ST+8A); C. barbatus, from the Be-tari River, 2n=66 (38M+22SM+4ST+2A); C. barbatus, from the São João River, 2n=66 (38M+22SM+6ST); C. difluviatilis, 2n=78 (6M+2SM+20ST+50A); C. robinae, 2n=84 (8M+18SM+16ST+42A); C. araguaiensis, 2n=94 (46M+40SM+8ST); and C. pulcher, 2n=102 (10M+14SM+42ST+36A). The species C. ehrhardti, C. nattereri, C. cf. nijsseni, C. pulcher, C. robinae, C. difluviatilis, and C. zygatus exhibited one chromosome pair with Ag-NORs; the species C. paleatus displayed two chromosome pairs with Ag-NORs; the species C. araguaiensis and C. barbatus showed three chromosome pairs with Ag-NORs; and the species C. undulatus presented five chromosome pairs with Ag-NORs. C-band positive segments were mostly restricted to the centromeric and pericentromeric regions in most chromosomes of C. ehrhardti, C. nattereri, C. cf. nijsseni, C. paleatus and C. undulatus; and in some chromosomes of C. zygatus. Besides pericentromeric segments, the species C. pulcher, C. robinae and C. difluviatilis exhibited some terminal segments in a few chromosomes. The species C. barbatus was characterized by the presence of C-band positive segments along the entire short arm of some chromosomes. The karyotype and chromosomal characteristics suggest the grouping of examined the species analyzed into five groups in agreement with previous hypotheses. The possible relation-ship patterns among species and/or groups are discussed.