Ultrastructural Observations of Taxonomic Importance on the Euglenoid Genera GyropaigneSkuja, ParmidiumChristen, and RhabdospiraPringsheim (Euglenida: Rhabdomonadina)

Character evolution in heterotrophic euglenids

“…scrolls) have also been observed in Rhabdomonas and Menoidium (Leedale and Hibberd 1974) (Fig. 10) and other rhabdomonads (Cann 1986). Similar structures were present around the canal of D. proteus.…”

“…Subsequent investigation by Cann (1986) showed that taxa other than Rhabdomonas and Menoidium (e.g., Gyropaine, Parmidium, and Rhabdospira) also possess the unusual supporting elements around the canal. Rhabdomonads also possess rigid pellicles with fused strips that are often arranged longitudinally ( Fig.…”

“…Figure 2 illustrates the progression of thought regarding the phylogenetic relationships of taxa possessing the four primary modes of nutrition. When the distinction was not made in the literature, "phagotroph" refers to bacteriotrophs and eukaryotrophs collectively; we refer only to distigmids and rhabdomonads sensu lato (Leedale and Hibberd 1974;Cann 1986;Preisfeld et al 2001) (Fig. 1d-e) as "osmotrophs" and not to those taxa that are clearly derived from phototrophs.…”

Phylogenetic position and inter-relationships of the osmotrophic euglenids based on SSU rDNA data, with emphasis on the Rhabdomonadales (Euglenozoa).

“…Our molecular data correspond well with morphological data. The monophyly of the Rhabdomonadales can be justified by the scroll, a structure which is built by a sheath of microtubules and amorphous material surrounding the canal (Leedale & Hibberd, 1974 ;Cann, 1986). Ultrastructural investigations show that the scroll is not present in other euglenid organisms and especially not in Distigma species (Yamaguchi & Anderson, 1994 ;Angeler, 1999).…”

“…At the molecular level, little is known about the phagotrophic and the osmotrophic euglenids. The lack of structures visible by light microscopy, such as plastids and ingestion devices, has led to confusing and inconsistent systematic positions and relations within the osmotrophs in general and the Rhabdomonadales in particular (Bourrelly & Georges, 1951 ;Cann, 1986 ;Christen, 1958Christen, , 1963Huber-Pestalozzi, 1955 ;Leedale, 1967 ;Leedale & Hibberd, 1974 ;Pringsheim, 1936Pringsheim, , 1942Pringsheim, , 1963Skuja, 1939Skuja, , 1948Skuja, , 1956. In this study we present the results of SSU rDNA data analysis with a focus on the position and interrelationship of the Rhabdomonadales, and reflect on possible evolutionary pathways.…”