Cytogenetics of Australian scorpions. II. Chromosome polymorphism in species of Urodacus (family Scorpionidae)

Abstract

The cytogenetic features of six species of scorpion from the Australian genus Urodacus (family Scorpionidae) were examined. Australian scorpionids possess monocentric chromosomes and male meiosis is achiasmate. Chromosome numbers are generally high and in some species extremely variable. Chromosome variation in one species, U. manicatus, was found to be due to fusion – fission polymorphism and variation in the number of small telocentric chromosome pairs. Additionally two populations exhibited extensive inversion heterozygosity. Available evidence suggests that female meiosis may also be achiasmate. The extensive numerical and structural heterozygosity found in U. manicatus may be related to the achiasmate meiosis, which allows regular pairing and disjunction of the multiple chromosome associations.Key words: achiasmate meiosis, chromosome polymorphism, structural heterozygosity, Robertsonian fusions.