Cytogenetic studies of Southern South-American Ilex

The dioecious genus Ilex (Aquifoliaceae) has been poorly studied from a cytogenetic point of view. Chromosome numbers of only ca. 5% of the species have been reported. In the present work the chromosome number of eight taxa from Argentina and Brazil are presented: Ilex taubertiana Loes., I. integerrima (Vell.) Reissek and I. pseudobuxus Reissek present 2n=40, being this the first report for these species. A diploid number of 40 is also confirmed for I. paraguariensis A. St. - Hil, I. brevicuspis Reissek, I. dumosa Reissek and I. theezans Reissek, and 2n=80 for I. argentina Lillo. Species with 2n=40 (n=20) show a regular meiotic behaviour with 20 bivalents, while I. argentina also shows a regular meiosis with 40 bivalents. Those individuals of I. paraguariensis analyzed in the present paper do not show a heteromorphic bivalent as previously reported and ascribed to sex chromosomes.