INVESTIGADORES
HONFI Ana Isabel
artículos
Título:
ASTERACEAE
Autor/es:
AGUILERA P. M.; DAVIÑA J. R.; HONFI ANA ISABEL
Revista:
TAXON
Editorial:
INT ASSOC PLANT TAXONOMY
Referencias:
Lugar: Viena; Año: 2012 vol. 61 p. 889 - 904
ISSN:
0040-0262
Resumen:
Chromosome numbers and karyotype morphology are described for three taxa of Heliantheae Cass. (Asteraceae) from NE Argentina for the first time. Angelphytum hatschbachii H. Rob. (27º17´S, 55º34´W) has 2n = 64 chromosomes and this is the first chromosome count for this species restricted to Misiones Province. Aspilia montevidensis (Spreng.) Kuntze var. montevidensis (27º34´S, 55º34´W) showed 2n = 44 chromosomes. This species naturally grows in northeast regions of Argentina (restricted to Chaco, Corrientes, Entre Ríos, Formosa, Santa Fe and Misiones Provinces), Brazil, Paraguay and Uruguay. Two varieties have been described for this taxon, var. montevidensis and var. setosa (Griseb.) Cabrera.  Aspilia montevidensis var. montevidensis is tetraploid with 2n = 4x = 44 chromosomes. Previous chromosome counts in A. montevidensis var. setosa have shown the existence of a polyploid complex composed by diploids (2n = 2x = 22), tetraploids (2n = 4x = 46) and hexaploids (2n = 6x = 68) with a base number of x = 11. Cytotypes of this complex are differentially distributed in eastern Argentina (2x), southern Brazil (4x) and southern Paraguay (6x). In agreement with previous reports, our tetraploid cytotype has x = 11, nevertheless at tetraploid level both varieties can be distinguished by morphological features and an additional pair of chromosomes. Calea uniflora Less. (27º17´S, 55º34´W) presented 2n = 32 chromosomes. This taxon occurs in northeast Argentina (restricted to Corrientes, Entre Ríos and Misiones Provinces), Brazil, Paraguay and Uruguay. Calea uniflora is diploid and possess a karyotype formula of 24 m + 8 sm. The smallest chromosome has 2.51 μm (m) and the largest 4.37 μm (m) with a mean chromosome length of 3.17 μm. The karyotype is unimodal (A2 = 0.16; R = 1.73) and symmetrical (A1 = 0.28; r > 2 = 0.18; i = 41.15; AI = 1.99) (Stebbins´ category 2A of karyotype asymmetry). The haploid genome has 50.76 μm. Our record is added to a previous contribution in which n = 16 II was observed in populations from Paraguay.