Karyotype analyses are important aid tools for taxonomic relationship studies. Native arboreal species found in the Brazilian "cerrado" have been poorly analyzed cytogenetically and cytotaxonomically. To determine diploid chromosome number, biometry and chromosome morphology of Anadenanthera colubrina ("angico-branco") and Guazuma ulmifolia ("mutambo"), seeds of these species were collected in Três Lagoas municipality, Mato Grosso do Sul, Brazil. The use of 8-hydroxiquinoleine 0.003M at 36ºC, for three hours caused chromosome separation. Giemsa coloration 2% for three minutes allowed the karyological study. Chromosome classification was based on the centromeric index. Anadenanthera colubrina has 2n = 26 chromosomes with chromosome medium length of 1.349 µm ± 0.017 and karyotype formulation 8SM + 14M + 2T + 2AC. Guazuma ulmifolia has 2n = 16 chromosomes with medium length of 1.225 µm ± 0.023 and karyotype formulation 4SM + 10M + 2T. These results can subsidize taxonomic and chromosomic manipulation studies, as well as the production of hybrid progenies in improvement programs.
karyotype; centromeric index; chromosome number; mitosis
