The distribution and variation of Synura species (Chrysophyceae) in Connecticut, USA

The genus Synura was found to be an important member of the phytoplankton communities in many Connecticut lakes, present in more than fifty percent of the 113 collections made during 1984. Thirteen taxa, including a new forma, Synura petersenii f. truttae , were recorded for the first time in Connecticut waters using SEM. S. petersenii was the most important species, present in forty-one percent of the samples. Evidence for denoting S. petersenii var. glabra as a form, instead of a variety, is presented. Ecological preferences for some species are discussed.     

Further observations on the scaled Chrysophycean and Synurophycean flora of the Ocala National Forest, Florida, U.S.A.

The distributions of silica-scaled chrysophytes in 30 freshwater ponds located in the Ocala National Forest, Florida, U.S.A., relative to chemical gradients are described. Phytoplankton, periphyton, and surface sediments from each of the 30 sites were collected in March of 2000 and later analyzed extensively with both scanning electron microscopy (SEM) and light microscopy (LM) for scaled chrysophytes. In addition, water samples were used to measure a suite of chemical characteristics, including specific conductance, pH, alkalinity, total phosphorus, total nitrogen, chlorophyll- a , chloride, sulfate and base cation concentrations. Overall, waterbodies included in this study are oligotrophic, dilute, poorly buffered and low in pH. Including six previously described species which are largely known only from the Ocala National Forest, we have identified forty-nine taxa of silica-scaled Chry-sophyceae and Synurophyceae, 23 of which were present in 5 or more waterbodies, indicating that lakes in this region are quite diverse and abundant in scaled chrysophytes. The most important species included Synura petersenii, S. echinulata and one recently reported new species from this region, Mallomonas wujekii , which was found in 73% of the lakes in this survey. The number of taxa found per lake ranged from 2 to 23 and observations include new records of several rarely reported species. Although the flora includes species commonly found in more northern regions, it also includes a group of taxa that appear to be endemic to the region and others commonly found in more tropical regions. Lastly, a new form found in ten ponds, Mallomonas transsylvanica f. curvata , is described.     

Silica-scaled chrysophytes from the bog-lake Baláta-tó, SW Hungary

Twenty-six species of silica-scaled chrysophytes representing the genera Chrysosphaerella (1 species), Mallomonas (19 species) and Synura (6 species) are reported based on transmission electron microscopy from the springtime flora of the slightly acidic bog-lake Baláta-tó, a Nature Reserve, situated in Southwest Hungary. Ten of them ( Mallomonas alata, M. clavus, M. insignis, M. mangofera, M. oviformis, M. papillosa, M. pillula, M. scalaris, M. transsylvanica and Synura multidentata ) are new records for Hungary. Furthermore, two species, M. pillula and M. scalaris are for the first time found in the Carpathian Basin and M. alata f. hualvensis is a new record for the flora of Europe. Dispersal problems are discussed.     

Two new species of Mallomonas (Synurophyceae) from the Ocala National Forest, Florida, U.S.A.

Two new species of Mallomonas, M. ocalensis and M. caerula , are described from a clearwater, acidic and oligotrophic waterbody in the Ocala National Forest, Florida, U.S.A. Mallomonas ocalensis , in the Series Doignonianae of the Section Torquatae, consists of relatively small cells with scales that have a series of parallel shield ribs with alternating thicknesses, collar scales with very short bristles and posterior scales with small protruding spines. Mallomonas ocalensis is most similar to Mallomonas dickii , but is distinguished from the latter species based on the highly variable thicknesses of the shield ribs and significantly larger scales. Mallomonas caerula , in the Series Mallomonas of the Section Mallomonas, consists of relatively large cells that bear large domed and dorneless scales, and long, robust and ribbed bristles. Bristles with and without helmets can be found. The shield, especially the distal portion, and the posterior flange of scales consists of series of more or less parallel ribs. Mallomonas caerula appears to be most closely related to Mallomonas acaroides var. acaroides and Mallomonas acaroides var. muskokana , but can be distinguished from the latter taxa on the basis of scale type, scale structure and bristle morphology. Both new species were found in the plankton and surface sediments of Blue Sink Pond.     

Spiniferomonas abrupta, sp. nov. and some rare species of Synurophyceae and Chrysophyceae, not formerly recorded from Denmark

Eight ponds and lakes were examined for scale-bearing chrysophytes (Synurophyceae and Chrysophyceae) and abiotic parameters. Samples were taken monthly, throughout one year. All species of scale-bearing chrysophytes were identified by transmission electron microscopy (TEM). Altogether 74 taxa were found including a new species of Spiniferomonas (S. abrupta sp. nov.). Some rare species, not formerly recorded from Denmark, were also observed: Mallomonas asmundiae, M. corcontica, M. pumitio var. silvicola, Paraphysomonas capreolata, P. elegantissima, P. limbata , and Spiniferomonas silverensis .     

Synurophyceae from the Southern Atlantic Coastal Plain of North America: A preliminary survey in Louisiana, USA

Forty-three taxa of Synurophyceae were identified by means of transmission electron microscopy of samples from ten different localities in southeastern Louisiana, USA, on the southern portion of the Atlantic Coastal Plain Province of North America. Samples were collected during a one month period when water temperatures ranged from 15.5–24.5"C. Sample pH values ranged from 4.4–7.2. Notable scale morphology variation was described for some taxa. The flora included three warm water taxa but was dominated by temperate and cosmopolitan taxa. Mallomonas prora and Synura australiensis are reported for the first time from North America. Comparisons with related studies from New World subtropical regions in Florida, USA, and Argentina were made, and significant North American range expansions were noted. The large number of aquatic habitats, 7–8 consecutive months at temperatures (6–20°C) best suited for development of synurophycean populations, and proximity to major bird migrations routes are postulated as explanations for the large number of reported species.     

Inorganic carbon acquisition in some synurophyte algae

Some characteristics of photosynthesis of three synurophyte algae, Synura petersenii, Synura uvella and Tessellaria volvocina were investigated to determine the mechanism of inorganic carbon (C(i)) uptake. All three species were found to have no external carbonic anhydrase, no capacity for direct bicarbonate uptake and a low whole-cell affinity for C(i). The internal pH of S. petersenii determined using (14)C-benzoic acid and [2-(14)C]-5,5-dimethyloxazolidine-2,4-dione was pH 7.0-7.5, over an external pH range of 5.0-7.5. Thus, the pH difference between the cell interior of S. petersenii and the external medium was large enough, over the alga's growth range, to allow the accumulation of C(i) by the diffusive uptake of CO(2). Monitoring O(2) evolution and CO(2) uptake by suspensions of S. petersenii at pH 7.0 by mass spectrometry did not indicate a rapid uptake of CO(2), and the final CO(2) compensation concentration reached was 24 +/- 0.7 microM. Furthermore, when the cells were darkened, a brief burst of CO(2) occurred before a steady rate of dark respiration was established, suggesting a loss of CO(2) by photorespiration. An examination of the kinetics of ribulose-1,5-bisphosphate carboxylase/oxygenase in homogenates of cells of S. petersenii, S. uvella and Mallomonas papillosa showed that values of the K(m) (CO(2)) were 28.4, 41.8 and 18.2 microM, respectively. These species lack the characteristics of cells with a CO(2)-concentrating mechanism because the cell affinity for C(i) appears to be determined by the relatively high CO(2) affinity of the Rubisco of these algae.     

Silica-scaled chrysophytes of the šumava National Park and the Tfeboñsko UNESCO Biosphere Reserve (Southern Bohemia, Czech Republic)

Thirty-five taxa of silica-scaled Synurophyceae and Chrysophyceae have been identified by means of transmission electron microscopy (TEM) from eight localities in the šumava National Park and the Trebon UNESCO Biosphere Reserve. Mallomonas alveolata, M. areolata, M. costata. M. doignonii var. doignonii. M. intermedia var. intermedia. M. punctifera, M. teilingii, M. transsylvanica. Synura leptorrhabda and Paraphysomonas takahashii are new records for the Czech Republic. Autecology and distribution of selected species are discussed.     

Morphological variation and ecology of Mallomonas crassisquama (Chrysophyceae)

Siver, P. A. & Skogstad, A. 1988. Morphological variation and ecology of Mallomonas crassisquama (Chrysophyceae). - Nord. J. Bot. 7: 99–107. Copenhagen. ISSN 0107–055X.
Mallomonas crassisquama is one of the most common and widely distributed species of Mallomonas . In this study we compare the morphology and ecology of the species based on 309 collections from 67 localities in Connecticut (U.S.A.) and Norway. The taxon produces a very complex siliceous coat consisting of four scale and two bristle types all of which have considerable structural variation. A new variety, M. crassisquama var. papillosa is described. Bristle production was found to be temperature dependent where cells formed serrated or helmet bristles under cold or warm conditions, respectively. M. crassisquama was found to exist over wide temperature, conductivity, phosphorus and pH ranges, however, was absent in samples with a pH <5.5.     

Records of chrysophytes with siliceous scales (Mallomonadaceae and Paraphysomonadaceae) from Finnish inland waters

Seventy-three taxa of silica-scaled chrysophytes were found with LM and TEM in 264 samples from 141 Finnish water bodies, including the genera Mallomonas (40 taxa), Synura (9), Chrysosphaerella (3), Spiniferomonas (8) and Paraphysomonas (13). More than half of the taxa are recorded for the first time from Finland and five (Mallomonas actinoloma v. actinoloma, M. favosa, M. mangofera f. gracilis, M. scrobiculata and Spiniferomonas serrata) are new to Europe. Most taxa are illustrated with TEM micrographs and the taxonomy of some interesting species is discussed in detail. The seasonal occurrence of the commonest species is described.     

Two new taxa in the Section Papillosae of the genus Mallomonas (Synurophyceae) from the Ocala National Forest, Florida, USA

Two new species of Mallomonas, M. binocularis and M. delanciana , are described from small, acidic, poorly buffered waterbodies in the Ocala National Forest, Florida, U.S.A. Both taxa are in the Section Papillosae, consist of relatively small cells covered with domed scales each bearing a single bristle, and have small tripartite scales with a small symmetrically placed dome. Scales of Mallomonas binocularis have shields that are covered with evenly-spaced papillae, two distinctive pores at the base of the V-rib and unornamented flanges. Mallomonas binocularis is most similar to Mallomonas paxillata, M. papillosa, M. rasilis and M. calceolus , but can be distinguished from the latter taxa on the basis of scale structure and bristle morphology. Scales of Mallomonas delanciana have shields with widely spaced papillae, a series of parallel ribs on the anterior flanges that usually continue around the dome, unornamented posterior flanges and lack rimmed pores in the posterior region of the shield. The density of the papillae on the shield, features of the dome and anterior flange, and the structure of bristles, clearly serve to separate M. delanciana from closely related species including M. papillosa, M. calceolus and Mallomonas conspersa.     

Algal species and light microenvironment in a low-pH, geothermal microbial mat community

Unicellular algae are the predominant microbial mat-forming phototrophs in the extreme environments of acidic geothermal springs. The ecology of these algae is not well known because concepts of species composition are inferred from cultivated isolates and microscopic observations, methods known to provide incomplete and inaccurate assessments of species in situ. We used sequence analysis of 18S rRNA genes PCR amplified from mat samples from different seasons and different temperatures along a thermal gradient to identify algae in an often-studied acidic (pH 2.7) geothermal creek in Yellowstone National Park. Fiber-optic microprobes were used to show that light for algal photosynthesis is attenuated to < 1% over the 1-mm surface interval of the mat. Three algal sequences were detected, and each was present year-round. A Cyanidioschyzon merolae sequence was predominant at temperatures of > or = 49 degrees C. A Chlorella protothecoides var. acidicola sequence and a Paradoxia multisita-like sequence were predominant at temperatures of < or = 39 degrees C.     

Mallomonadaceae (Chrysophyceae) from Malaysia and Australia

The Mallomonadaceae (Chrysophyceae) of Malaysia and Australia are described by scanning and transmission electron microscopy. Thirty taxa are reported from Malaysia, twenty eight for the first time. Eighteen taxa are reported from Australia, twelve for the first time. Twelve taxa are reported for the first time from the tropics. Four new taxa, Mallomonas ocellata sp. nov., M. tropica sp. nov., M. favosa f. gemina f. nov. and Chrysosphaerella astrea sp. nov. are described and the diagnosis of Mallomonas adamas Harris et Bradley is emended.     

Mallomonas wujekii (Synurophyceae), a new species from Florida, U.S.A.

A new species of Mallomonas, M. wujekii sp. nov., belonging to the Series Tonsuratae is described from a dilute, acidic locality in Florida, U.S.A. Bristle bearing domed scales are restricted to the anterior end, and scales are orientated with their longitudinal axes at a 60° to 90° angle with the longitudinal axis of the cell. Cells have three types of scales, domed anterior scales, domeless body scales and spined posterior scales. All scales possess papillae that are restricted to the shield and have one rib positioned on each end of the posterior flange. The new species is believed to be most closely related to Mallomonas tonsurata and M. galeiformis . The combination of characters of the bristles is unique among taxa of Mallomonas .