A light and electron microscopic study of Scherffelia dubia, a new member of the scaly green flagellates (Prasinophyceae)

In clonal culture Scherffelia dubia (Perty) Pascher shows a considerable range of morphological variation, with different cell shapes being produced including those typical for three other species of Scherffelia Pascher ( S. opisthostigma Skuja, S. ovata Pascher, S. pelagica Skuja) and one species of Tetraselmis Stein ( T. bichlora Ettl & Ettl). It is concluded these taxa should be reduced to the synonymy of S. dubia , the type species of Scherffelia. The general cell morphology of S. dubia is described in detail, including a serial section and absolute configuration analysis of the flagellar apparatus. S. dubia is compared with species of Tetraselmis of which ultrastructural details are known and it is shown that both genera are very similar but the generic distinction is nevertheless justified. Main features of distinction include the pyrenoid (present in Tetraselmis but lacking in Scherffelia ) and the chloroplast (single and more or less cup‐shaped in Tetraselmis , two separate lateral chloroplasts in Scherffelia ). Both genera are accommodated in the same family, the correct name being Chlorodendraceae and not Tetraselmidaceae or Platymonadaceae which have often been used.