Comparative ultrastructure of the cytoskeleton and nucleus of Distigma (Euglenozoa)

Although the ultrastructure of the pellicle is currently considered as a va luable tool for systematic assessments within euglenoids, comparative aspec ts at the genus level are largely lacking. Whereas species of the pigmented genus Euglena have been the focus of some comparative ultrastructural anal yses, colourless taxa have been generally neglected. This study attempts to describe the cytoarchitecture of the non-pigmented euglenoid genus Distigm a, with special emphasis on the pellicle and nucleus morphology of D. curva tum Pringsheim, D. elegans Christen, D. glabrum Pringsheim ex Ettl nom. nud . non D. glabrum Christen, D. gracile Pringsheim, D. proteus var. proteus E hrenberg emend. Pringsheim, D. proteus var. longicauda Angeler and D. senni i Pringsheim. All taxa possess the typical plastic type of pellicle which a llows for euglenoid movements. Interspecific variations in pellicular strip construction may explain differences in form and degree of "metaboly". Bas ed on the results the taxonomic significance of pellicle and nucleus ultras tructure in the genus can be discussed. Finally, some remarks on obviously mislabelled cultures are given.