Meiosis, polyploidy and taxonomy op the pleurotaenium mamillatum complex (Desmidiaceae)

Abstract

Meiosis is described in germinating zygospores from crosses between various karyotypes and ploidy levels of Pleurotaenium mamillatum. It is chiasmate and conventional in character and the chromosomes have localized centromeres. Sexual crossing, resulting in viable, fertile offspring, occurs to a surprising degree between strains with widely disparate chromosome numbers, ploidy levels and geographical location. Since P. mamillatum has a clean taxonomic record this name is adopted for our biological species, but some strains could be legitimately identified as P. ehrenbergii and P. coronatum by the alpha practice of comparative iconography. These names are retained in this paper to describe strain lineages. © 1976 Taylor & Francis Group, LLC.