Chromosome Number Variation in the Myrtaceae and Its Taxonomic Implications

Abstract

New chromosome number determinations are reported for some 150 Western Australian species of the Myrtaceae. These include the lowest number (n = 5) so far recorded in the family and several newly recorded descending dysploid series. Dysploid chromosome numbers are far less common than the base chromosome number of n = 11 but parallel dysploid series have occurred in many groups and some have played a role in the origin of genera. Polyploidy has been successful at the intraspecific and interspecific levels but is of limited evolutionary potential.

The cytoevolutionary trends in the Myrtaceae are examined in relation to taxonomic problems within the family and in relation to cytoevolution in the woody Australian flora as a whole. Smith- White's suggestion that a more natural generic classification in the Chamelauciinae could be obtained by grouping species with the same base chromosome numbers is found to be untenable.