Phacus

Abstract: Phylogenetic analyses of 35 strains including 25 previously published sequences and 10 which have been newly sequenced, representing two species of Euglena, five species of Phacus and three species of Astasia, were carried out using the SSU rDNA. Parsimony, distance and maximum-likelihood inferred phylogenies support (1) monophyly of the euglenoids, (2) kinetoplastids as the sister group, (3) the phagotrophic Petalomonas cantuscygni Cann et Pennick anchoring the base of the euglenoid lineage, (4) evolution of phototrophy within the euglenoids from a single event, (5) multiple origins of osmotrophic euglenoids and (6) polyphyly of the genera Euglena Ehrenberg and Phacus Dujardin. Analyses also indicate that Lepocinclis Perty, Trachelomonas Ehrenberg and Astasia Dujardin are polyphyletic. In addition, the results suggest that neither the Euglenales nor the Eutreptiales form a monophyletic lineage, thus questioning currently available classifications. Concerning the phagotrophic mode of nutrition, the data suggest that the feeding apparatus arose multiple times.

Abstract: A Bayesian analysis, utilizing a combined data set developed from the small subunit (SSU) and large subunit (LSU) rDNA gene sequences, was used to resolve relationships and clarify generic boundaries among 84 strains of plastid-containing euglenophytes representing 11 genera The analysis produced a tree with three major clades: a Phacus and Lepocinlis clade, a Discoplastis clade, and a Euglena, Colacium, Trachelomonas, Strombomonas, Monomorphina, and Cryptoglena clade The majority of the species in the genus Euglena formed a well-supported clade, but two species formed a separate clade near the base of the tree A new genus, Discoplastis, was erected to accommodate these taxa, thus making the genus Euglena monophyletic The analysis also supported the monophyly of Colacium, Trachelomonas, Strombomonas, Monomorphina, and Cryptoglena, which formed two subclades sister to the Euglena clade Colacium, Trachelomonas, and Strombomonas, all of which produce copious amounts of mucilage to form loricas or mucilaginous stalks, formed a well-supported lineage Our analysis supported retaining Strombomonas and Trachelomonas as separate genera Monomorphina and Cryptoglena formed two well-supported clades that were sister to the Colacium, Trachelomonas, and Strombomonas clade Phacus and Lepocinclis, both of which have numerous small discoid chloroplasts without pyrenoids and lack peristaltic euglenoid movement (metaboly), formed a well-supported monophyletic lineage that was sister to the larger Euglena through Cryptoglena containing clade This study demonstrated that increased taxon sampling, multiple genes, and combined data sets provided increased support for internal nodes on the euglenoid phylogenetic tree and resolved relationships among the major genera in the photosynthetic euglenoid lineage

Abstract: Almost since the creation of the genus Euglena (Ehrenberg), the taxa assigned to it have been separated, split apart, and reorganized into new genera based on morphological relationships, resulting in the creation of the genera Phacus (Dujardin), Lepocinclis (Perty), Astasia (Pringsheim), and Khawkinea ( Jahn and McKibben) based on intuitive methods. In an effort to assess the validity of these genera, we have used small subunit (SSU) rDNA data to generate a phylogenetic framework for these genera, with particular attention to the genus Euglena. Using the conserved sequence areas, we performed a phylogenetic analysis using parsimony, maximum likelihood, and distance methods. These different criteria have resulted in trees of the same topology. The euglenoid clade was composed of phagotrophic euglenoids at the base, which gave rise to phototrophs that in turn gave rise to osmotrophs. Among the photosynthetic taxa, the biflagellate form diverged prior to the uniflagellate form. Additionally, the need for a revision in the taxonomy of some of these genera was demonstrated. Currently, taxa from the photosynthetic genera Euglena, Phacus, and Lepocinclis do not form monophyletic clades, but are intermixed with each other as well as with the osmotrophic taxa, Astasia and Khawkinea.

Abstract: 18S rRNA genes (SSU rDNA) of five newly sequenced species were used as molecular markers to infer phylogenetic relationships within the euglenoids. Two members of the order Euglenales (Lepocinclis ovata Playfair, Phacus similis Christen), two of the order Eutreptiales (Distigma proteus Ehrenberg,, D. curvata Pringsheim) and Gyropaigne lefevrei Bourelly et Georges of the order Rhabdomonadales were used in parsimony, maximum likelihood, and distance analyses. All trees derived from SSU rRNA data strongly supported the monophyletic origin of the Euglenozoa, with kinetoplastids as sister clade to the euglenoids and Petalomonas cantuscygni Cann et Pennick diverging at the base of the monophyletic euglenoid lineage. The data also supported the theory that phagotrophic euglenoids arose prior to osmotrophs and phototrophs. A lineage of Peranema trichophorum Ehrenberg and all sequenced Euglenales formed a sister clade to the osmotrophs. This suggests that the evolution of phototrophy within the euglenoids radiated from a single event.