Morphological studies of 16 strains belonging to the genus Monomorphina revealed a single, parietal, orbicular chloroplast in their cells. The chloroplast has a tendency to be perforated and disintegrates in aging populations and thus may appear to be many chloroplasts under the light microscope. A single chloroplast in the cells of Cryptoglena skujae is also parietally located and highly perforated. It never forms a globular and closed structure, but is open from the side of the furrow, resembling the letter C. We have verified the Monomorphina pyrum group (M. pyrum-like) on the basis of phylogenetic analysis of SSU rDNA and morphological data. The strain CCAC 0093 (misidentified as M. reeuwykiana) diverges first on the SSU rDNA phylogenetic tree. The rest of the M. pyrum-like strains form a tight cluster, subdivided into several smaller ones. Because morphological differences between the M. pyrum-like strains (including the strain CCAC 0093) do not conform to the tree topology, we suggest that they all (except the strain CCAC 0093) belong to M. pyrum. We designate a new species, M. pseudopyrum, for the strain CCAC 0093, solely on the basis of molecular characters. We also suggest that M. reeuwykiana and similar species should stay in Phacus and Lepocinclis unless detailed molecular and morphological studies show otherwise. Emended diagnoses of the genera Monomorphina and Cryptoglena and the species M. aenigmatica are also proposed, as well as the delimitation of an epitype for M. pyrum, the type species for the genus Monomorphina.

Eighteen new 16S rDNA and 16 new 18S rDNA sequences from 24 strains, representing 23 species of photoautotrophic euglenoids, were obtained in nearly their entire length. Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses were performed on separate data (39 sequences of 16S rDNA and 58 sequences of 18S rDNA), as well as on combined data sets (37 sequences). All methods of sequence analysis gave similar results in those cases in which the clades received substantial support. However, the combined data set produced several additional wellsupported clades, not encountered before in the analyses of green euglenoids. There are three main well-defined clades (A, B/C/D, and G) on trees from the combined data set. Clade G diverges first, while clades A and B/C/D form sister groups. Clade A consists of Euglena species sensu stricto and is divided into three sub-clades (A1, A2, and A3). Clade A3 (composed of E. deses and E. mutabilis) branches off first; then, two sister clades emerge: A1 (composed of E. viridis-like species) and A2 (consisting of E. agilis and E. gracilis species). Clade B/C/D consists of the Strombomonas, Trachelomonas, Cryptoglena, Monomorphina, and Colacium genera. Clade G comprises Phacus and Lepocinclis, as well as the Discoglena species of Euglena, with Discoglena branching off first, and then Phacus and Lepocinclis emerging as sister groups.

Verification of morphological diagnostic features and the establishment of three epitypes for three species of Phacus Dujardin-Phacus pleuronectes (O. F. Müll.) Dujardin, Phacus orbicularis Hübner, and Phacus hamelii Allorge et Lefèvre-was performed based on literature studies and analysis of morphological (cell shape, cell size, and periplast ornamentation) as well as molecular (18S rDNA) characters. Periplast ornamentation was recognized as a main diagnostic character, distinguishing P. orbicularis from P. pleuronectes and P. hamelii. Phacus orbicularis has struts running perpendicular to the longitudinal axis of the strips, while P. pleuronectes and P. hamelii do not. On the SSU rDNA tree, obtained by the Bayesian method, P. orbicularis, P. pleuronectes, and P. hamelii belong to three distinct clades. Some of the phylogenetic relationships are not resolved, but there are at least three Phacus species (P. hamatus, P. platyaulax, P. longicauda; for taxonomic authors, see Introduction) that are more closely related to P. orbicularis than is P. pleuronectes. Phacus hamelii is more closely related to P. ranula and the assemblage of several species of Phacus, which have small cells, than to P. orbicularis or P. pleuronectes.

Morphological and molecular studies, as well as original literature reexamination, necessitate establishment of five Euglena species with a single axial, stellate chloroplast [Euglena viridis (O. F. Müller) Ehrenberg 1830, Euglena pseudoviridis Chadefaud 1937, Euglena stellata Mainx 1926, Euglena pseudostellata sp. nov., and Euglena cantabrica Pringsheim 1956], three species with two chloroplasts (Euglena geniculata Dujardin ex Schmitz 1884, Euglena chadefaudii Bourrelly 1951, and Euglena pseudochadefaudii sp. nov.), and one species with three chloroplasts (Euglena tristella Chu 1946). The primary morphological features, allowing distinction of the considered species are the presence and the shape of mucocysts, as well as the number of chloroplasts. Spherical mucocysts occur in E. cantabrica and E. geniculata, while spindle-shaped mucocysts are present in E. stellata, E. pseudostellata, E. chadefaudii, E. pseudochadefaudii, and E. tristella. No mucocysts are observed in E. viridis and E. pseudoviridis. Two new species (E. pseudochadefaudii sp. nov. and E. pseudostellata sp. nov.) differ from the respective species, E. chadefaudii and E. stellata, only at the molecular level. Molecular signatures and characteristic sequences are designated for nine distinguished species. Emended diagnoses for all and delimitation of epitypes for seven species (except E. viridis and E. tristella) are proposed.

We studied the morphological diversity and analyzed the small subunit rDNA sequences of two taxa formerly known as Euglena spirogyra Ehr. and Euglena fusca (Klebs) Lemmermann. Our studies confirmed that the two should have the rank of a species, namely Lepocinclis spirogyroides (Ehr.) Marin et Melkonian and Lepocinclis fusca (Klebs) Kosmala et Zakryś comb. nov. (Euglenophyceae).We are defining new diagnostic features for these species, namely the size and the shape of the cells and the shape of the papillae, as well as designating epitypes for them.Enormous morphological plasticity of euglenoid cells has been well known for a long time, but recently there have been more thorough studies. It was shown experimentally that changes in physicochemical conditions are responsible for changes in cell morphology (