Flagellate green algae of class Prasinophyceae which is regarded as the most primitive class of green plants. Nephroselmis olivacea

Nephroselmis is a genus of class Prasinophyceae which is regarded by some as the most primitive class of green plants. These are free living, flagellate green algae. Cell body and flagella are covered by at least two layers of scales which are produced in the golgi apparatus. Both fresh water and marine species have been detected. The cells divide by transverse binary cell division, though haplontic life cycle has also been reported. Nephroselmis olivacea is a fresh water species. The cells are semicircular or bean-shaped, about 7-13 �m in length and 6.5-8 �m in width. It has two unequal flagella. There is a single chloroplast which contains a pyrenoid. It is heterothallic in nature and survives unfavorable conditions as a zygote. Complete chloroplast DNA sequence of N. olivacea has been determined. It is circular DNA of 200,799 bp, with an overall A + T content of 57.9%. Based on pairwise comparisons of plastid genomes from different algae sequenced so far, N. olivacea appears to branch near the base of the Chlorophyte lineage.