Blidingia minima var. stolonifera var. nov. (Ulvales, Chlorophyta) from British Columbia: systematics, life history and morphogenesis

Blidingia minima var. stolonifera var. nov. is described from Vancouver, British Columbia. In previous literature this variety may have been confused with B. chadefaudii and B. minima var. minima. The new variety is part of the B. minima species complex in which spores germinate by evacuating the original spore and forming a germ tube. B. minima var. stolonifera is characterized by the development of marginal filaments on the basal disc that have one to five colourless cells and terminate in a cell from which a new disc grows. Colourless cells are devoid of chloroplasts and nuclei, and contain only small remnants of cytoplasm. The runner system is considered a mechanism of vegetative growth and propagation that enables a disc to cover a large amount of substratum before producing erect, unbranched thalli. In field and in culture, B. minima var. stolonifera typically reproduces by means of quadriflagellate zoospores; however, three plants from Vancouver formed biflagellate spores. These germinated poorly and developed into highly irregular, branched thalli.