THE FLAGELLAR APPARATUS ULTRASTRUCTURE IN LEPTOSIRA ERUMPENS (DEASON AND BOLD) LUKESOVA AND ITS CONTRIBUTION TO THE UNDERSTANDING OF PHYLOGENETIC-RELATIONSHIPS WITHIN THE MICROTHAMNIALES (CHLOROPHYTA)

The actual spatial configuration of the flagellar apparatus in biflage llate zoospores of the terrestrial green alga Leptosira erumpens is de scribed. The basal bodies are displaced with respect to each other in the counter clockwise direction (CCW). The two types of microtubular r oots consist of 2 microtubules (R2) and 8 microtubules (R8) respective ly. The latter type of microtubular root is arranged in a 7-over-1 ori entation. The two basal bodies are connected to each other anteriorly by a large striated distal connecting fibre. The microtubular roots ar e connected to the adjacent basal body via a striated proximal fibre a nd linked with the lower side of the distal connecting fibre. A single striated rhizoplast runs from one basal body along a large mitochondr ion towards the nuclear envelope. The distinct eyespot (stigma) is int imately associated with a series of ca. 10 microtubules originating fr om one of the eight-membered microtubular roots. In order to investiga te the role that non-molecular characters play in the understanding of evolutionary relationships within the Microthamniales, a datamatrix w as compiled for a preliminary phylogenetic analysis. Along with the pr esent data of L. erumpens non-molecular (in great majority morphologic al) data of 15 more microthamnialean species and 2 selected outgroup s pecies were included within this set. Despite incompleteness of the da ta, a distinct phylogenetic signal was found. This encouraged us to co mpare our results with a recent phylogenetic reconstruction based on m olecular data.