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Canadian coastal waters of the Pacific Ocean and the Atlantic Ocean as well as inland freshwater habitats in Ontario were sampled for centrohelid heliozoans (free-living heterotrophic single-celled organisms) over a period of nearly five decades. More than 60 species and subspecies were revealed, including 1 Triangulopteris, 1 Raphidocystis, 2 Pseudoraphidocystis, 3 Raineriophrys, 4 Pseudoraphidiophrys, 12 Choanocystis, 15 Pterocystis, and 25 Acanthocystis taxa. Of these, 22 were officially named and described as new to science based primarily on the morphology of the siliceous scales that cover the cell. New species were compared with images and/or descriptions of close 'relatives' to validate their new species assignments. New data on five species of Acanthocystis and one species of Choanocystis required revisions of their descriptive taxonomy that in some cases resulted in the splitting off of separate species or subspecies. Very little can be concluded about global distribution of centrohelid heliozoans, owing to the paucity of records. For many of the taxa reported here, previous records consist of just one or two findings from other parts of the world. One example is Choanocystis antarctica Tikhonenkov and Mylnikov, 2011 that was previously known only from Antarctic seawater, but is reported here from an Ontario softwater lake. Key words: heliozoans, silica-scaled protists, taxonomy, new species, Haptista, Centroplasthelida, Introduction The centrohelid heliozoans comprise a relatively large group of over 100 free-living species with filose pseudopodia and endogenously produced siliceous scales that cover the cell. Where found, in a [...]

Light and scanning electron microscopy were used to describe Neidium petersiveri sp. nov., a previously unnamed diatom found in the Canadian waters of Lake Superior. It had been reported previously as single cells of an unidentified Neidium species from four widely separated regions in North America: Michipicoten Island (Lake Superior, Ontario, Canada), Cape Cod (Massachusetts, United States), a Quebec river (Quebec, Canada), and the Back River (Nunavut, Canada). There are superficial resemblances to Neidium mirum Krasske and Neidium calvum Østrup, but there are significant differences in frustule size and shape as well as the pattern of striae on the valve face that render N. petersiveri unique. There was not a significant correlation between frustule lengths and widths in N. petersiveri, owing to a relatively small range within the width data that resulted in much higher width-to-length ratios among shorter cells than for longer cells (74 cells measured). Other significant aspects of morphologic variation include various shapes and configurations of the lacinial fissures and of the proximal raphe fissures, and the sporadic occurrence of pit-like depressions in the axial and central regions of the valves, which suggest that variations in these characters likely have limited value as discriminating characters at the species or subspecies levels. Key words: Lake Superior, bi-raphid diatom, Neidium, frustules. La microscopie optique et la microscopie électronique à balayage ont été utilisées pour décrire Neidium petersiveri sp. nov., une diatomée jusqu'alors sans nom trouvée dans les eaux canadiennes du lac Supérieur. Elle avait été signalée précédemment comme cellules uniques d'une espèce de Neidium non identifiée provenant de quatre régions très éloignées en Amérique du Nord : l île Michipicoten (lac Supérieur, Ontario, Canada), Cape Cod (Massachusetts, Etats-Unis), une rivière du Québec (Québec, Canada) et la rivière Back (Nunavut, nord du Canada). Il existe des ressemblances superficielles avec Neidium mirum Krasske et Neidium calvum Østrup, mais il y a des différences significatives dans la taille et la forme des frustules ainsi que dans le motif des stries sur la face de la valve qui rendent N. petersiveri unique. Il n'y avait pas de corrélation significative entre les longueurs et les largeurs des frustules chez N. petersiveri, en raison d'une gamme relativement faible dans les données de largeur qui a entraîné des rapports largeur-à-longueur beaucoup plus élevés parmi les cellules courtes que pour les cellules plus longues (74 cellules mesurées). D'autres aspects significatifs de la variation morphologique comprennent les différentes formes et configurations des fissures laciniales et des fissures du raphé proximal, ainsi que l'apparition sporadique de dépressions en forme de puits dans les régions axiales et centrales des valves, ce qui suggère que les variations de ces caractères ont probablement une valeur limitée en tant que caractères de discrimination au niveau de l'espèce ou de la sous-espèce. [Traduit par la Rédaction] Mots-clés : lac Supérieur, diatomée biraphide, Neidium, frustules., Introduction Diatoms are microscopic, single-celled photoautotrophs and are an important component of aquatic food webs in both freshwater and marine ecosystems. Marine diatoms appear to have been responsible (during the [...]

Abstract: We examined long-term changes in phytoplankton composition from 1981 to 2003 in seven intensively studied lakes on the southern Canadian Shield in Ontario, Canada. Significant (P < 0.05), temporally [...]

Red snow caused by dinoflagellates is a phenomenon rarely reported, described from the European Alps from 1914 onwards, and subsequently observed outside Europe on several occasions in Ontario, Canada. Considerable taxonomic confusion exists regarding the identity of the organism(s) causing red snow, but the most recent occurrence in 2016 in Ontario has now allowed detailed studies, including LM, SEM, TEM and molecular sequencing of the causative species. We conclude that the two species originally described as the cause of red snow, Glenodinium pascheri and Gyrodinium nivale, are synonymous and that the appropriate name for the organism is Borghiella pascheri (syn. Woloszynskia pascheri) as suggested by Moestrup & Calado in the recent volume of the Süsswasserflora. The central part of Borghiella pascheri cells is tomato red and filled with numerous organelles, whose ultrastructure indicates modified chloroplasts. Lack of cultures has prevented chemical characterization of the red pigment. Formation of temporary cysts was common in the samples. Transformation of the motile cells into temporary cysts was followed in detail, and the cysts were shown to be surrounded by the fused inner membranes of the amphiesmal vesicles, which became the cell membrane of the cysts, covered by the fused pellicle precursors. The cell membrane from the motile cell was discarded together with the outer amphiesmal vesicle membrane and the thin thecal plates, and the temporary cysts were therefore not surrounded by any pattern of vesicles. Sexual reproduction resulted in the formation of hypnozygotes. Although the species possessed several unusual features, DNA sequencing showed it to belong to Borghiella. The culture established in 1965 from the Botanical Garden in Göttingen, Germany and generally identified as Woloszynskia pascheri belongs to a separate species of Borghiella, to be described separately.The occurrence of red snow caused by dinoflagellates is discussed. [ABSTRACT FROM AUTHOR]

The morphology of tests (“shells”) representing populations of the small testate amoeba Cyphoderia laevis Penard, 1902 (Cercozoa, Euglyphida) from Canada and Hungary was quantified. Despite often considerable variation the cross-sectional shape of tests, multivariate statistical analysis confirmed the general uniformity of test morphology within populations and between populations at both local (regional, inter- and intra-watershed) scales and over inter-continental scales (Canada and Hungary). Corrections are suggested to recently published misidentifications of C. laevis as Corythionella georgiana Nicholls. The differences between these two taxa are subtle, but significant, and are emphasized here to help preclude similar errors in the future. Schaudinnula nana Badewitz, 2003 is shown to be a superfluous synonym for Cyphoderia laevis . Cyphoderia truncata Schulze, 1875 has some similarities to C. laevis , but its status remains unresolved. Some preliminary reservations are expressed about the classification of Cyphoderia laevis within the genus Cyphoderia owing mainly to its Corythionella -like scale structure and other characteristics of its test that appear to be outside the “usual” range found in other Cyphoderia species. [ABSTRACT FROM AUTHOR]

In 1961, the testate amoeba Nebela kivuense Gauthier-Lièvre et Thomas, 1961 was described for the first and only time from an area near Lake Edward in the Democratic Republic of the Congo (at 0.002° N Latitude). The lack of recent reports of this species, despite exhaustive surveys of the testate amoebae fauna of the major continents of the world, suggested that N. kivuense was a rare species perhaps endemic to a small, local equatorial region of the African continent. This paper reports its rediscovery from two wetland-conifer forest eco-systems in southern Ontario, Canada (at 44° N Latitude), thus changing dramatically our previous perception of its very restricted global distribution. This has implications for the idea held by many students of biogeography that there is a special category of microscopic protists that contains truly rare species and their rarity, perhaps together with specific habitat requirements and tolerances, limits opportunities for dispersal around the world. The N. kivuense story is a clear example of the dangers of inferring endemism from rarity. [ABSTRACT FROM AUTHOR]

Six new marine species of the silica-scaled heterotrophic genus Thaumatomastix are formally described: two were found in Canadian Atlantic Ocean coastal waters (T. asymmetrica sp. nov. and T. sablensis sp. nov.) and four from Canadian Pacific Ocean coastal waters (T. inornata sp. nov., T. multipora sp. nov., T. gwaii sp. nov. and T. curvata sp. nov.). These discoveries more than double the number of known marine species of this genus from four to ten. The scale structures of all differ significantly from those of previously known species and therefore warrant erection as new species. Amended descriptions of two previously little-known freshwater species (T. triangulata and T. nigeriensis) are provided based on specimens found in freshwater ponds and lakes in Ontario, Lanada, and provide evidence refuting the recent published proposals to transfer T. triangulata back to the photo-autotrophic genus Chrysosphaerella and to transfer T. nigeriensis to the related thaumatomonad genus Reckertia. Until now, all known species of Reckertia (including several taxa previously classified in Thaumatomastix) were marine. This paper describes the first known freshwater species of Reckertia (R. hindoni sp. nov.) found in two separate Ontario ponds. The similarities and differences among many of the marine and freshwater species of Thaumatomastix suggest a common ancestor but significant evolutionary divergence over time and space. [ABSTRACT FROM PUBLISHER]

Near-shore benthic sediment samples collected at low tide from the western Atlantic Ocean (Sable Island, Nova Scotia, Canada) and the eastern Pacific Ocean (Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada) were searched for little-known species of the rhizarian (Cercozoa) genera Pinaciophora, Rabdiaster and other related rotosphaerids. Several representatives with complete investitures of silica-scales (the structure of which is taxonomically diagnostic) were studied by transmission and scanning electron microscopy. The validity of the genus Pinaciophora (sensu Penard, 1904) as defined by a single type of plate-scale only, was strengthened by the discovery of Pinaciophora rubicunda and of another previously undescribed entity, both of which lacked spine-scales. Several earlier reports of loose scales from marine habitats, and erroneously identified as the freshwater P. fluviatilis, might be assigned to P. marina sp. nov. The new genus Thomseniophora was erected to include all ‘Pinaciophora' previously known to produce spine-scales and seven new taxa were described. Six other little-known species of Thomseniophora, Pinaciophora and Rabdiaster were described from the Canadian west coast (Pacific Ocean) including one new species of Pinaciophora. The addition of Thomseniophora brings the number of genera assigned to the Rotosphaerida to six: Pinaciophora, Thomseniophora, Rabdiaster, Rabdiophrys and Pompholyxophrys. The presence of several apparently closely related taxa in the same collection (same location and sampling date) strengthens the conclusion that relatively small differences in the morphology of their siliceous scales were more likely caused by genetic differences than by environmental influences. [ABSTRACT FROM PUBLISHER]

Three independent methods of time-series analysis were applied to a 37-year record of total phosphorus and chlorophyll-a data collected at four sampling stations representing the upper, middle and lower sections of the Bay of Quinte, NE Lake Ontario, Canada. The three methods were used to build consensus around the significance of the apparent declines in total phosphorus (TP) and chlorophyll-a (Chl-a) concentrations following two interventions: (I) point-source phosphorus loading reductions of about 50% to the upper hay in the winter of1977-1978 and (2) the establishment of Zebra Mussels (Dreissena spp.) in the early to mid-1990's. The methods were applied to May to October monthly means and included: (I) nonparametric tests that accounted for persistence and seasonality and determined the statistical significance of step -trends, (2) A RIM A-Intervention modelling that produced forecasts into post-intervention time periods that were compared statistically to measured data and (3) regime shift detection for identifying the significance of persistent steps after removal of the seasonal components of the data series (modelled as periodic functions). Strong gradients in total phosphorus (TP) and Chl-a concentrations between the upper and lower Bay of Quinte still existed three decades after reductions in point-source loadings of TP to the upper bay, where, during 2000-2008, May-October average TP was 3.8 times higher and Chl-a, 2.9 times higher than in the lower bay. The Remedial Action Plan May-October TP objective of 0.030 mg l-1 for the upper Bay of Quinte was not achieved consistently in recent years. Concurrence among the data analysis methods suggests that the relative decreases in the upper bay TP (31%) and Chl-a (37%) after phosphorus loading reductions were greater than in the lower bay (0% and 10%, respectively). The relative decreases in the upper bay TP (0%) and Chl-a (29%) associated with Dreissena establishment were less than those measured in the lower bay (20% and 50%, respectively). [ABSTRACT FROM AUTHOR]

Six new marine species of the testate amoebid genus Paulinella are described using light and electron microscopic observations of material from Canada's Pacific Ocean coastal waters. In order of test (shell) size, from smallest to largest, the following new species are proposed: P. carsoni sp. nov., P. agassizi sp. nov., P. suzukii sp. nov., P. lauterborni sp. nov., P. multipora sp. nov. and P. gigantica sp. nov. Included in this survey are new observations on P. indentata Hannah, Rogerson & Anderson, from Canadian Pacific Ocean locations, but previously known only from Scottish coastal waters, and the common brackish/freshwater species P. chromatophora, from Ontario (Canada). These new discoveries more than double the number of previously known species of Paulinella, a genus significant for its role as a secondary producer in marine benthic ecosystems and for the possible role of its type species (P. chromatophora) as a model system for the endosymbiosis hypothesis of the evolution of chloroplast-bearing organisms. [ABSTRACT FROM PUBLISHER]

Abstract: The testate amoebid genus Corythionella inhabits beach sands and includes three marine and two freshwater species of the “acolla-complex”, all characterized by a poorly developed flared collar surrounding the pseudostomal aperture. Multivariate statistical methods (cluster analysis, principal coordinates analysis, non-metric multidimensional scaling ordination and discriminant analyses) were applied to morphologic characters of the test (shell) of the members of this complex in order to visualize and assess the degree of similarity among them. Graphical displays of the results of these analyses clearly revealed distinct separations between all pairs of species, including a sixth previously un-named taxon described here as a new species (Corythionella darwini n. sp.). Discriminant functions were developed to assist in identification of Corythionella with reduced oral collars. C. darwini was discovered in Pacific Ocean beach sand samples from western Canada and is characterized by a test with a median length, width, height and pseudostome width of 53, 20, 19 and 12μm, respectively. It presents the least variability in test morphology of all known species in the “acolla-complex” (coefficients of variation ranging between 3 and 5.6% for the four test variables) and is further distinguished from the other members of the complex by its distinctive near-cylindrical shape. [Copyright &y& Elsevier]

Twenty lakes recovering from a century of atmospheric acid deposition over Northeastern Ontario were resurveyed for phytoplankton following a 20-year period and were compared with a 23-year study of an experimentally acidified lake, L302S (Experimental Lakes Area, ON, Canada). Phytoplankton species significantly tracked abiotic changes during both acidification and chemical recovery in all lakes based on concordance testing. However, ordination analyses showed that many phytoplankton communities had not returned to their preacidification state. Significant explanatory variables of taxonomic responses were pH, dissolved organic carbon (DOC), and inorganic nutrients (N, P), based on canonical correspondence analysis (CCA). Increases in DOC and pH influenced a significant taxonomic shift from acid-tolerant dinoflagellates to a diverse assemblage of cyanobacteria, chlorophytes, and diatoms. Declining nitrogen levels defined a secondary environmental gradient, which was characterized by a decrease in filamentous green algal abundance. L302S remained remote in ordination space from the more chronically and heavily polluted lakes in Northeastern Ontario, indicating that experimental acidification provided a conservative estimate of the true damage to atmospherically polluted lakes. However, L302S did increasingly resemble lakes in Northeastern Ontario, suggesting that experimental acidification simulated the impacts of moderate levels of atmospheric pollution. Our findings demonstrate the importance of ecological history in understanding the responses by boreal lake ecosystems to environmental change. [ABSTRACT FROM AUTHOR]

Abstract: Since its description 35 years ago from Quebec, Canada, the poorly known monospecific testate rhizopod genus Puytoracia (type species, Puytoracia bergeri) has been reported only from the Himalayan region of Nepal. This species was recently found at 13 locations in Ontario, Canada, and the range of form variation of the species from widely separated sites is described. At two of these sites, boreal forest bogs in north-western Ontario, a second, previously unidentified, Puytoracia species was also found and described (as Puytoracia bonneti n. sp.). Differences between the two species were clearly demonstrated statistically using morphometric variables. The large elliptical scales covering the test of P. bonneti (easily seen with relatively low-power microscopy) provide the most important criterion for separating this species from some Trinema species having superficially similar test morphology (e.g. Trinema penardi Thomas & Chardez, or Trinema galeata (Penard) Jung.). On the basis of test structure, it is suggested that P. bonneti occupies a taxonomic position relative to P. bergeri that is similar to that occupied by T. penardi relative to Trinema enchelys (Ehr.) Leidy. Results of this study further confirm the logical position of Puytoracia within the family Trinematidae, close to, but distinct from, the genera Corythion and Trinema. [Copyright &y& Elsevier]

Species of the testate rhizopod genera Arcella and Cyclopyxis are found predominantly in the benthos of shallow ponds, forest pools, marshes and other freshwater habitats. Their taxonomy is based on the morphology of their tests — the shell-like structure that houses the living single-celled amoeboid protoplast. This paper describes a new species of Cyclopyxis discovered in two coniferous forest bogs, and a new species of Arcella from a Typha-dominated marsh on the north shore of Lake Ontario, Canada. Cyclopyxis acmodonta Nicholls n. sp. differs from its closest relative C. stellata (Wailes) Deflandre 1929 in its much smaller size and its irregularly shaped pseudostomal aperture, which is embellished with numerous, tiny, sharp-pointed tooth-like quartz granules around the interior margin. Although the saucer-like indentations over the dorsal surface of the test of A. formosa Nicholls, Meisterfeld & Török n. sp. resemble similar structures found in several other Arcella species, the large size of A. formosa (165-235 µm in diameter) and its low profile (low height-to-diameter ratio) are the main features distinguishing this new species from other Arcella species. [ABSTRACT FROM AUTHOR]

Two species of the poorly known testate rhizopod genus Campascus, C. minutus Penard and C. simcoei n. sp., are described statistically from populations in Ontario, Canada. The Ontario specimens of C. minutus revealed a considerably wider range in test size and shape than has been previously reported. LM micrographs of the test structure in C. minutus are provided for the first time and illustrate a test covered with small, variously shaped, tight-fitting particles of apparently exogenous origin. C. simcoei differs from the seven other previously described species by its bulbous shape with up to five posterior short “horns”. Median test length, width, height and aperture diameter are 103, 57, 54, and 24.5 m, respectively. Its test is covered with variously shaped, flat particles, similar to those found in C. minutus. The continued inclusion of the genus Campascus in the family Cyphoderiidae (a group defined by a test covered with endogenously-produced circular, reniform or elliptical scales) is untenable. It is proposed here to transfer the genus to the family Psammonobiotidae Gol. emend Meisterfeld, where it shares test characteristics with genera such as Alepiella, Edaphonobiotus and Micropsammella. [Copyright &y& Elsevier]

The life cycle of a previously undescribed chrysophyte, assigned to the new genus Rhizoochromonas, is described. It includes a small motile stage with heterokont flagellation which invades a Dinobryon lorica. Reproduction by cell division of the nearly spherical rhizopodial vegetative stage frequently leads to expulsion of the host protoplast through overcrowding of the lorica. Endogenous cysts (stomatocysts) are also formed within the Dinobryon lorica. The new family, Brehmiellaceae, is established to accommodate pseudopodial / rhizopodial chrysophytes with heterokont flagellation in the motile stage. Rhizoochromonas endoloricata gen et sp. Nov. has been found at two widely separated softwater locations in Onlario, and at one it constituted a major component of the planktonic flora during the autumns of six successive years. [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]

Chrysochromulina breviturrita sp. Nov. is described as a new haptonema-bearing member of the freshwater Prymnesiophycear. It is ca. three times larger than the only other known freshwater member of the genus (C. parva Lackey) and possesses a haptonema only ca. 0.2-0.3 as long as the haptonema of C. parva. Two equal flagella (1.5-2 × as long as the haptonema), a large contractile incuole, two parietal plastids, a single pyrenoid, nucleus, chrysolaminarin-like droplets and a food vacuole are features readily observed with the light imcroscope. Dried and shadowcast whole mounts examined with the clectron microscope reveal the cell surface covered with two types of small, delicate scales: outer spined scales with a club-shaped terminus and with the spine anchored to a circular to oval base-plate by 2-6 (7) branching arms; and, spineless oval plate seales with concentric lines and radiating ridges on one face and parallel ridges on the other. C. breviturrita has been found in nine lakes in Ontario (Canada). Preliminary observations suggest that it is an important component of lake plankton and has probably not been detected in previous work, more because of its fragility than because of its scarcity. Living specimens are a prerequisite for initial identification, since cells frequently supture and haptonemata are often lost when the organisms are killed with the commonly used fixatives. [ABSTRACT FROM AUTHOR]

Two new species of Pseudokephyrion are described from Little Aurora Lake, Ontario, Canada. The distribution of both P. taeniatum sp. nov. and P. auroreum sp. nov. is restricted for reasons which are not clear; neither species was found in samples from lakes adjacent to Little Aurora Lake. All lakes in the vicinity are very dilute, oligotrophic and acidic. [ABSTRACT FROM AUTHOR]