Comparative cytogenetic analysis of eleven species of subfamilies Neoplecostominae and Hypostominae (Siluriformes : Loricariidae)

The family Loricariidae with about 690 species divided into six subfamilies, is one of the world's largest fish families. Recent studies have shown the existence of several problems in the definition of natural groups in the family, which has made the characterization of the subfamilies and even of some genera quite difficult. With the main objective of contributing for a better understanding of the relationships between loricariids, cytogenetic analysis were conducted with two species of Neoplecostominae and nine species of Hypostominae that, according to morphological and molecular data, may belong to a new monophyletic unit. The results obtained showed a marked chromosomal conservation with the presence of 2n = 54 chromosomes and single interstitial Ag-NORs in all species analyzed. Considering that Neoplecostominae is the primitive sister-group of all other loricariids, with exception of Lithogeneinae, this karyotypic structure may represent the primitive condition for the family Loricariidae. The cytogenetic characteristics partaken by the species of Neoplecostominae and Hypostominae analyzed in the present study reinforce the hypothesis that the species of both these subfamilies might belong to a natural group.