Life cycle of Punctaria latifolia (Chodariaceae, Phaeophyceae) from Buenos Aires, South America

M.C.GAUNA; N. PIZANI; E. R. PARODI

IHERINGIA. SERIE BOTANICA

Fundação Zoobotânica do Rio Grande do Sul

Lugar: Rio Grande do Sul, Brasil; Año: 2006

0073-4705

Abstract: The life cycle of Punctaria latifolia was studied under culture conditions (140 µmol m-2 s-1; 12 h/12h; 21 ± 1 °C temp.). Fertile sporophytes were collected in the intertidal zone of Bay San Blas (Buenos Aires Argentina, South America), during August and December 2003. These macroscopic laminar plants were found adhered to the rocky substrate and on Spartina alterniflora plants. This species presented haplodiplobiontic heteromorphic life cycle as well as a direct type, when plurispores produced plethysmothalli. Sporophytes from natural environment presented both plurilocular and unilocular sporangia. Unispores were released from these later. The asexual reproduction was evidenced by the germination of unispores that originated microscopic filamentous gametophytes. Zygotes from terminal and intercalar gametangia reconstituted the macroscopic diploid phase. Chromosome counts gave 16 and 8 for diplo- and haplo- phases, respectively. The objective of this study was to describe the morphology of the natural populations, the life cycle under culture conditions and the kariology of P. latifolia to confirm the sexual reproduction.