Abstract
The polytene chromosomes of Cr. algarum from the Black Sea coast of Bulgaria were analysed. Salivary-chromosome map of the species was made. The diploid set of chromosomes is 2n=6. The first couple is submetacentric, the second-metacentric and the third-acrocentric. The three couples have significant differences in length. The chromosomes are concentrated in chromocentre. A comparatively high degree of chromosomal polymorphism was estimated and it was probably in relation with the distribution of the species. Aberrations, specific for every year and repeatedly occurring aberrations, determining the presence of “stable” polymorphism were found. Differences in the numbers of chromosomes in the somatic and in the sexual cells were reported.
