TEM observations of field-collected cells of Pachycladella umbrina from Taiwan and P. zatoriensis from France, confirm earlier LM records of a pyrenoid and bifurcated appendages. The pyrenoid is scattered with spoke-like channels focusing, when present, to a central cavity. The cell wall is surrounded by a layer of fluffy hair-like material and four appendages. These appendages are hollow tubes, closed at their bifurcated or sometimes blunt apex. The appendages of P. umbrina are covered with many electron-dense conical and hollow warts. EELS microanalysis of P. umbrina and P. zatoriensis reveals that the appendages contain Fe and Fe+ Mn respectively. Because of preservation problems, other features were not investigated. Field-collected P. umbrina differs from a culture of the same species (REYMOND & HEGEWALD 1990) by the presence of a pyrenoid, warts and iron. The taxonomy of Pachycladella and other genera of the family Treubariaceae is still unclear.