Ultrastructure of flagellated chrysophytes. II. Uroglena and Uroglenopsis

Although the general fine structure of Uroglena and Uroglenopsis is not unlike that of other genera found in the Chrysophyceae, one feature was found to be of taxonomic value. This characteristic was the lack of thylakoids penetrating the pyrenoid matrix. Perhaps after more members of the Chrysophyceae are examined, the variance of pyrenoid types may not prove to be of taxonomic value at the generic or species level as in the Dinophyceae (Dodge and Crawford 1971). Comparison of the two genera to each other emphasises their great similarity with respect to general morphology and ultrastructural detail. Features which are now listed as typical of the Chrysophyceae (Hibberd and Leedale 1972) were observed in Uroglena and Uroglenopsis: plastids with three thylakoids per band, a peripheral girdle band, a layer of chloroplast ER that is continuous with the outer membrane of the nuclear envelope, flagella of unequal length (see Casper 1972), and a parabasal Golgi body.