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The two-celled colonial synurophyte genus Chrysodidymus was originally distinguished from its close relative Synura on the basis of the colonies always being of two cells, the shape of the cells and the odd swimming nature of the colony. Recently, based on gene sequence data, Chrysodidymus was found to be deeply nested within the Synura clade. As a result Chrysodidymus was placed in synonymy with Synura and a new combination, S. synuroidea, was made for the basionym C. synuroideus. Based on our observations and findings of two-celled colonies originally described under the genus Chrysodidymus, we propose descriptions of two new species Synura papillosa and Synura prowsei and an emended description for Synura synuroidea. Scales of S. synuroidea are significantly smaller than those of the two proposed species and possess an exceptionally wide posterior rim that is perforated with large holes of uneven diameters. Scales of the new species are significantly larger with narrow posterior rims that lack holes. Scales of S. prowsei possess anterior ribs that connect the ends of the posterior rim to the base of the spine and lack surface papillae, whereas scales of S. papillosa have surface papillae, but lack the anterior ribs. In addition, the base plate pore patterns are distinctive for each species. We further designate a neotype for S. synuroidea since the original holotype has been lost. All three species favour dilute, shallow, highly acidic water bodies often with highly coloured dissolved organic matter (CDOM). [ABSTRACT FROM AUTHOR]

A new species of Mallomonas (Synurophyceae), Mallomonas jejuensis sp. nov., has been found in Jeju Island, South Korea. This species is placed in the series Mangoferae (section Torquatae) because it has a collar of elongated domed scales, domeless body scales, rear scales with spines and all scales ornamented with papillae. The morphological characteristics of the scales and bristle of the new species are described by EM and compared with those reported for the other species of the series Mangoferae. [ABSTRACT FROM AUTHOR]

We used batch cultures of three strains of the unicellular synurophyte Mallomonas caudata to investigate the effects of nitrate, phosphate, silicate and light intensity on population growth and growth rate. The three strains were isolated from three different reservoirs in Kyungpook Province, Korea. For all three strains, we observed high population growth under all nutrient concentrations studied, except at nitrate concentration below 0.8 μM. The maximum growth rate (μmax) occurred at 8.2 μM or 16.5 μM nitrate, depending on the strain, and at 11.5 μM phosphate. Silicate concentration had no effect on growth rate. With respect to light intensity, the maximum population growth and maximum growth rates (μmax) occured between 42 and 104 μmol m−2 s−1 depending on strain and culture temperature. Population growth of these three strains under batch culture occurred over a wide range of nutrient and light intensities, but there seemed to be strain-specific differences that may represent adaptations to local environments. [ABSTRACT FROM AUTHOR]

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Complex bristle types formed by species in the genus Mallomonas include those with helmet or lance-shaped apices. The ornamentation on each side of the helmet has been thought to be equivalent or symmetrical, whereas on a lance-shaped bristle an expanded portion folds over one side of the shaft to form an asymmetrical structure. We describe, for the first time, helmet bristles with a distinctly asymmetrical design, also formed by the folding of a siliceous membrane over one side of the helmet. We postulate that the asymmetrical helmet represents a structure that combines the formation of a symmetrical helmet and a lance-shaped design on the same bristle. Further, we report structurally similar asymmetrical helmet bristles, lance-shaped bristles and scales that are unambiguously assigned to Mallomonas asmundiae in Middle Eocene sediments from a maar lake in northern Canada, supporting the hypothesis that scale and bristle morphology in the Synurophyceae has undergone extensive prolonged evolutionary stasis. Given differences in scale morphology and the presence of asymmetrical helmet bristles, we transfer the North American endemic Mallomonas acaroides var. muskokana to the rank of species. Further, we formally describe Mallomonas dispar and M. lancea, fossil species with asymmetrical helmet bristles and lance-shaped bristles, respectively. The taxonomic and biogeographic significance of asymmetrical and lance-bearing bristles is discussed. [ABSTRACT FROM AUTHOR]

A new species, Mallomonas duerrschmidtiae, with characteristics common to both Mallomonas crassisquama (Asmund) Fott and Mallomonas pseudocoronata Prescott, is described from acidic lakes low in specific conductance and total phosphorus concentration. Characteristics of scales, bristles and spines serve to separate the three taxa. The length and area of scales of M. duerrschmidtiae are significantly larger than those of M. crassisquama but smaller than those of M. pseudocoronata. Although the anterior submarginal ribs of scales of M. duerrschmidtiae may become extended to form short wings, the scales lack the large forward projecting anterior wings characteristic of scales of M. pseudocoronata. Features of the dome and junction between the arms of the V-rib and anterior submarginal ribs also serve to distinguish between the three species. Cells of M. duerrschmidtiae also possess long, smooth and thick spines on their posterior scales and lack helmet bristles. M. duerrschmidtiae has different maxima along pH, temperature, specific conductance, total phosphorus and seasonal gradients than either M. crassisquama or M. pseudocoronata. Discriminant analysis, based on nine morphological characters, was used to successfully classify body scales of the three species. The importance of M. duerrschmidtiae as a bioindicator in future lake monitoring and paleolimnological inference studies is discussed. [ABSTRACT FROM AUTHOR]

Three new species and one new variety of Mallomonas (Mallomonadaceae, Chrysophyceae) were discovered in Ontario, Canada. Descriptions based on electron microscopy of silica scale structure are provided for Mallomonas inornata sp. nov., Mallomonas perfossa sp. nov., Mallomonas sexangularis sp. nov., and Mallomonas gutata var. simplex var. nov. The relationships of the scale structures of the new taxa with those known for other similar species are discussed. About 80 Mallomonas species and subspecies now are known from North America. [ABSTRACT FROM AUTHOR]

Two species of Mallomonas M heterospina Lund and M. americana Durrschmidt were recorded for first time from Argentina, Tierra del Fuego Transitional features between the two species in scale ornamentation and bristle are discussed On that bases the abolishment of the series Hamatae and Heterospinae is proposed. [ABSTRACT FROM AUTHOR]

This article focuses on the characteristics of Chrysophytes in the southern part of Hyogo Prefecture, Japan. Several studies have been made on Mallomonas in Japanese freshwater ponds and lakes. Mallomonas taxa so far recorded in Japan form thirty-one percent of one hundred and thirty-seven taxa which have previously been reported in the world. Forty-three taxa of the genus Mallomonas found in Doro-ike Pond, Hoshino-ike Pond, Sengari Reservoir and Yasuba-ike Pond are listed in the article. Cells of Mallomonopsis peroneides are oblong ellipsoidal, and covered with smooth bristles and several kinds of scales. Cells of Mallomonas rasilis are ellipsoidal and covered with serrated bristles and two kinds of scales, small apical scales and body scales.

The article presents studies on scale-bearing chrysophytes in the south basin of Lake Biwa, Japan. Of the scale-bearing chrysophytes, only 3 species, Mallomonas fastigata, M. helvetica and Synura uvella have been recorded by a light microscopical study. The scale-bearing chrysophytes, such as Mallomonas and Synura (Mallomonadaceae) and Paraphysomonas (Paraphysomonadaceae), possess their characteristics of species on their minute scales and bristles, as well as their lorica form. Therefore the electron microscopy is the most useful method to identify them accurately.

Presents several studies on the phytoplankton of the Panama Canal and its major tributary. Occurrence of eight taxa of scaled chrysophytes from the area; Identification of siliceous scale-bearing organisms by means of electron microscopy; Collection of samples of phytoplankton or algae.

The article discusses seasonal fluctuation of Spiniferomonas (Chrysophyceae, Synuraceae) in two ponds on Mt. Rokko, Japan. The seasonal fluctuation of the genus Spiniferomonas was investigated from April 1975 to April 1977 in two ponds that were situated 800 meters above sea level on Mt. Rokko in Kobe City, Japan. Six species and two unidentified taxa were found in both ponds. Among them, Spiniferomonas bourrellii, Spiniferomonas trioralis and Spiniferomonas bilacunosa were dominant. All taxa were from an oligotrophic pond.

A new species of Mallomonas, M. alphaphora ( Chrysophyceae), was found in freshwater ponds in the Perth region, Western Australia. It is distinguished from other species of Mallomonas by its very distinctive scale and bristle morphology and is placed in a new section, Alphaphorae, of the genus Mallomonas. [ABSTRACT FROM AUTHOR]

Previously, DNA sequences were determined for the entire ITS/5.8S region by direct sequencing of PCR amplification products. 28 sequences were obtained from 12 species of Synurophyceae, including Tessellaria volvocina, Chrysodidymus synuroideus, six species of Synura and four species of Mallomonas. Sequences also were determined from multiple strains of some species, including 15 strains of Synura petersenii. The length of these sequences varied from 495–598 bp. The large amount of ITS/5.8S length variation made initial attempts in determining reliable sequence alignment difficult and precluded their use in phylogenetic analyses of the class. Subsequently, the approach of Bogler & Simpson (1996) was investigated where reiterative, computer assisted alignments were generated and the quality of the alignment was evaluated by homoplasy index and consistency index values. However, these alignments also were equivocal. ITS/5.8S sequences sorted the 15 S. petersenii strains into two well supported ITS lineages. One ITS type included ten isolates from North America while isolates from the second ITS type included one each from Germany and Australia and three from North America. Results are presented here where the sequences from the 15 S. petersenii isolates were used to characterize ITS-1 and ITS-2 RNA transcript secondary structure. Next, this information was expanded to include ITS/5.8S sequences from the other taxa in the class. Finally, the characteristics of ITS 1 and ITS 2 RNA transcript secondary structure were used as a guide to align all of the ITS/5.8S sequences from the Synurophyceae in a final phylogenetic analysis. [ABSTRACT FROM AUTHOR]

An abstract of the article "An Evaluation of Promising Barcode Genes for Synura Petersenii (Synurophyceae)," by G.H. Boo and colleagues is presented.