The soil alga Jaagiella alpicola Vischer (Chlorophyta), a new member for the order Pleurastrales

Jaagiella alpicola Vischer is an edaphic alga that forms filaments and cell packets. The cells have a single nucleus and a plate-like parietal chlorop last without a pyrenoid. A metacentric mitotic spindle was observed during cell division; the parental cell wall contributes to the formation of the c ommon transverse cell wall. Biflagellated zoospores were formed in groups o f two or four within non-modified cells of the thallus; the parental cell w all does not contribute to the zoospore cell envelope. The zoospores were n aked, almost flattened, globally asymmetric and contained a single chloropl ast with an eyespot. The basal bodies showed counter-clockwise orientation and were connected by a striated proximal and distal connecting fibre; the flagellar roots consist of a cruciate (7(6+1)-2-7(6+1)-2) microtubular root system. The ultrastructural and reproductive features of J alpicola sugges t its inclusion in the order Pleurastrales.