Cytogenetic Considerations on the GenusAstyanax(Pisces, Characidae). II. Occurrence of Natural Triploidy

摘要

Astyanax schubartiis characterized by a diploid number of 36 chromosomes. In the present paper we report on the occurrence of a specimen with 54 chromosomes, a probable case of natural triploidy as shown not only by the chromosome number but also by the good morphological correspondence between the chromosomes of the 3x and2xindividuals. The fertilization of an unreduced oocyte is postulated as the probable cause of this triploidy.