Abstract
To establish taxonomy and understand phylogenetic relationships among strains and species of the photosynthetic euglenoids, we performed phylogenetic analyses based on a four gene sequence dataset (nr SSU and LSU rDNA, and pt SSU and LSU rDNA) from 343 taxa (including three outgroup). The phylogenetic tree based on the combined dataset was split into two major clades: Euglenaceae and Phacaceae. The family Euglenaceae was a well-supported monophyletic group containing eight genera (Colacium, Cryptoglena, Euglena, Euglenaformis, Euglenaria, Monomorphina, Strombomonas, and Trachelomonas), each representing a monophyletic lineage, except for the genus Euglena. The genus Euglena was divided into three subclades (A1, A2, and A3) and was paraphyletic due to Euglena archeoplastidiata being grouped with the genus Euglenaria and E. cf. velata with the genus Colacium. The family Phacaceae was supported as a monophyletic group and contained three genera (Discoplastis, Lepocinclis, and Phacus). The genus Phacus contained traditionally defined members as well as the non-traditional P. warszewiczii and P. limnophila, which support the generic concept of Linton et al. (2010).
Highlights
Euglenoids are an ancient and diverse lineage of asexual unicellular eukaryotic flagellates predominantly found in freshwater, and found in marine, soil and tapole rectum (Brumpt and Lavier, 1924)
The tree supported the Euglenales being separated into two main lineages (Figure 1): the family Euglenaceae and the recently established family Phacaceae
Euglenaceae The family Euglenaceae was monophyletic with strong support values and consisted of eight genera: Colacium, Cryptoglena, Euglena, Euglenaformis, Euglenaria, Monomorphina, Strombomonas, and Trachelomonas
Summary
Euglenoids are an ancient and diverse lineage of asexual unicellular eukaryotic flagellates predominantly found in freshwater, and found in marine, soil and tapole rectum (Brumpt and Lavier, 1924). Since the first taxonomical description of green euglenoids by Ehrenberg (1830a,b, 1835), their classification and phylogenetic relationships have continuously changed. Traditional taxonomic studies were based on morphological features such as cell shape, chloroplast type and number, flagellar length, paramylon shape and distribution, cell surface ornamentation, and degrees of metaboly. A result of these limited diagnostic features and profound morphological plasticity lead to mistakes in proper identification, e.g., E. stellata and E. viridis with a single stellate chloroplast, or lorica morphology in Trachelomonas and Strombomonas being influenced by environmental conditions (Pringsheim, 1956; Singh, 1956). Morphological classification system and phylogenetic relationship at genus and species levels have needed clarification based on molecular data
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