Estudios cromosómicos en Vernonia cincta y V. scorpioides (Vernonieae, Asteraceae)

DEMATTEIS, M.

Bonplandia

Instituto de Botánica del Nordeste

Lugar: Corrientes; Año: 2000 vol. 10 p. 155 - 161

Vernonia cincta Griseb. and V. scorpioides (Lam.) Pers. (Asteraceae, Vernonieae) are two closely related entities that have been considered alternatively by different authors as a single species, varieties of the same entity and two different species. In the present study was carried out a detailed chromosome analysis in an attempt to clarify the status and relationships of the two entities. The cytological study revealed that Vernonia cincta has a somatic chromosome number of 2n=60 with a karyotype formula composed of 36m + 16sm + 8t, while V. scorpioides presents 2n=66 and a karyotype with 34m + 20sm + 12t. In addition to the chromosome number, the species showed certain other differences between their karyotypes, principally in formula, total length and asymmetry level. Chromosomal information here reported supports the specific status of both taxa. The presence of telocentric chromosomes in V. cincta and V. scorpioides would distinguish to them from the remainder New World species of Vernonia that commonly have metacentric and submetacentric pairs. The karyotype differences between V. cincta and V. scorpioides may be explained by the occurrence of structural rearrangements such as centric fusions or traslocations. This hypothesis is well supported by the similar total karyotype length of both taxa and the higher mean chromosome length of V. cincta, which presents a lower number of telocentric chromosomes than V. scorpioides.