Chromosomal polymorphisms due to supernumerary chromosomes and pericentricinversions in the eyelidless microteiid lizard Nothobachia ablephara (Squamata, Gymnophthalmidae)

Cytogenetic studies were performed on eight specimens of the monotypic micr oteiid lizard Nothobachia ablephara, endemic of the sand dunes of the middl e Sao Francisco river, in the semiarid caatinga, State of Bahia, Brazil. Ch romosomes from fibroblast cultures were analysed after conventional, Ag-NOR staining, C-, and replication R-banding. A basic karyotype of 2n = 62, con sisting mostly of subtelocentric and acrocentric chromosomes of decreasing size, was found in five specimens. Diploid number variation (2n = 63 and 2n = 64) occurred in two specimens due to the presence of one and two medium- sized subtelocentric supernumerary chromosomes (Bs). The Bs were not clearl y distinguishable from the autosomes in Giemsa-stained metaphases and C-ban ding, but showed late replication after R-banding. Polymorphisms of pairs 1 and 5, observed in three different combinations, including acrocentrics, s ubtelocentrics, submetacentrics and metacentrics, were interpreted as the r esult of small pericentric inversions. Variation in the number of Ag-NORs w as also reported. A chromosomal mechanism of sex determination of the XX:XY type is present in this species. Our data add more evidence to confirm the remarkable chromosomal variability that has been found in Gymnophthalmidae .