Pseudocharaciopsis TexensisGen. et sp. nov., a new member of the Eustigmatophyceae

A new genus of the Eustigmatophyceae and its type species, Pseudocharaciopsis texensis, are described. The actively growing vegetative cells have a short stalk and an attaching disc. The pyrenoid is spherical and is attached to the typically single, parietal chloroplast. There may be 1–4 or sometimes more pyrenoids and chloroplasts in older cells. Zoospore ultrastructure is similar to that of Ellipsoidion acuminatum Pascher. However, the zoospore of P. texensis is characterised by the presence of two large, conspicuously membrane-bounded osmiophilic vesicles and by the fan-shaped (in transverse section) flagellar swelling instead of the T-shaped one of Ellipsoidion acuminatum.