Cytotaxonomy of some species of Vernonanthura and Vernonia (Asteraceae, Vernonieae) from South America

Abstract

The number and behavior of meiotic chromosomes in four populations of three species of Vernonanthura were analyzed. It was observed that all stages of meiosis were stable without chromosomal irregularities. The somatic chromosome number is reported for four populations of three species of Vernonanthura and two populations of Vernonia. All species were diploid with 2n = 34. The first chromosome count is presented for Vernonanthura chaquensis (2n = 17II and 2n = 34). The karyotypes were determined for Vernonanthura lucida (32m + 2sm), V. oligactoides (24m + 10sm) and V. pseudolinearifolia (28m + 6sm); they are presented for the first time. The total length of the karyotype was 31.67μ–40.48 μm. The average chromosome length was 1.86μ–2.38 μm and the centromeric index was 38.61–42.99. Vernonanthura oligactoides showed the smallest variation of chromosome length within the karyotype (1.42 μm) while V. squamulosa had the biggest (2.15 μm). The different karyotypic parameters were analyzed with two statistic tests. The resulting species arrangement from Unweighted Pair Group Method with Arithmetic Mean (UPGMA) grouping analysis fully fits with that obtained with principal component analysis (PCA). Both tests demonstrated congruence between karyotypic parameter and classification based on morphological characters.