Cytotaxonomy of some species of the South American genus Lessingianthus (Asteraceae, Vernonieae)

Abstract

Mitotic chromosome numbers of 32 populations belonging to 23 species of the genus Lessingianthus H.Rob.

(Vernonieae, Asteraceae) were determined. The chromosome number of all examined plants was found to be based

on x = 16. The numbers observed varied from 2n = 32 to

2n = 176. The results include the first report of the chromosome number for 11 species: L. lanatus (2n = 32),

L. varroniifolius (2n = 32), L. cataractarum (2n = 64),

L. intermedius (2n = 64), L. argenteus (2n = 96), L. centauropsideus (2n = 96), L. profusus (2n = 96), Lessingianthus sp. nov. 1 (2n = 96), Lessingianthus sp. nov. 2

(2n = 128), L. robustus (2n = 160), and L. macrocephalus (2n = 176). New chromosome numbers were found in the

four other species: L. rubricaulis, L. laniferus, and L. sellowii were tetraploid with 2n = 64, while L. oxyodontus was

hexaploid with 2n = 96. B chromosomes were observed in

L. coriaceus and L. varroniifolius. Lessingianthus macrocephalus (2n = 11x = 176) is reported as the first case of an

odd polyploid and the higher chromosome number of Lessingianthus. The significance of the results is discussed in relation to chromosomal data available for the genus.