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Acta Botanica Brasilica

versión impresa ISSN 0102-3306versión On-line ISSN 1677-941X

Resumen

MARCON, Adriana Buarque; BARROS, Iva Carneiro Leão  y  GUERRA, Marcelo. Karyologyof some pteridophytes species occurring in the northeast of Brazil. Acta Bot. Bras. [online]. 2003, vol.17, n.1, pp.19-26. ISSN 0102-3306.  http://dx.doi.org/10.1590/S0102-33062003000100002.

Seven species of homosporous and three of heterosporous pteridophytes belonging to eight families, were cytogenetically analysed using conventional staining techniques. This is the first count for Brazilian populations of these species. Two karyological parameters were analysed: chromosome number and structure of interphase nucleus. Chromosome morphology and occurrence of satellites have also been evaluated in some species. Prior reports on chromosome counts are unkown for two of the species analysed: Selaginella convoluta (Arn.) Spring (2n=24) and Thelypteris serrata (Cav.) Alston (2n=72), which presented numbers already expected for their genera. The other species analysed had the following chromosome numbers: Acrostichum aureum L., 2n=60; A. danaeifolium Langsd. & Fisch.,2n=60; Blechnum occidentale L.,2n=124; Cyathea microdonta (Desv.) Domin, 2n=138; Hemionitis palmata L.,2n=60; Marsilea quadrifolia L., 2n=40; Osmunda cinnamomea L., n=22 and Selaginella kraussiana (Kunze) A. Braun., 2n=20.The only cytogenetical irregularity observed was the presence of a tetravalent in a single individual analysed of O. cinnamomea.The structure of the interphase nuclei was more densely reticulated and homogeneously stained in the homosporous species, while in the heterosporous ones, it was more variable, almost always presenting different numbers of chromomers or chromocenteres.

Palabras clave : pteridophytes; chromosome number; interphase nuclei.

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