Morphology and life cycle of Batrachospermum atrum var. puiggarianum (Batrachospermales, Rhodophyta)

Abstract

Batrachospermum  atrum var.  puiggarianum was collected for the first time in Buenos Aires province. The identification of samples was based on microscopic morphology and chromosomic number analyses of each generations of the life cycle under culture conditions. The thalli were studied
with optical microscopy, and karyology according to carmine acetic technique. Life cycle showed three generations: an haploid gamethophyte, a diploid carposporophyte and the last  Chantransia diploid phase. Gametophytes exhibited separate whorls of densely compressed primary branches, some of those branches bearing spermatangia or carpogonium. Internodes were constituted by globose axial cells and cortical cells. The ovoidal carposporophytes were formed by gonimoblastic filaments bearing terminal carposporangia. The Chantransia stage was characterized for short filaments of few cells. The studied material showed a chromosome haploid number n = 4, and diploid number 2n = 8.