Collinsiellopsis, a New Genus of Green Algae

Collinsiellopsis expansa gen. et sp. nov. is described as a member of the Chlorosphaerales and placed with Collinsiella in a new family, the Collinsiellaceae. The frond is gelatinous, solid and firm, indefinitely expanded, with many delicate, irregularly arranged, rough ridges on the upper surface. The cells are pyriform to spherical, with a stalk system; each cell is uninucleate and has a cup-shaped chloroplast with a single pyrenoid, the opening of the chloroplast being at the lower end of the cell. The main constituent of the matrix of the frond is a xylogalactan, while that of the cell walls is cellulose. Vegetative cells are capable of transforming into sporocysts in which two or four zoospores are produced. The zoospores have four flagella and are markedly flattened, ovate when viewed from one side and lanceolate when viewed from the other side. They develop asexually into a new frond which again produces quadriflagellate zoospores.