Studies in selected fragilarioid diatoms (Bacillariophyceae) from Lake Hovsgol, Mongolia

Three fragilarioid diatom taxa were studied in detail at the light microscopy and scanning electron microscopy levels from samples collected from Lake Hovsgol, Mongolia. Two of the taxa are new to science, described here as Staurosirella minuta Morales et M. B. Edlund and Pseudostaurosira tenuis Morales et M. B. Edlund, and may be endemic to Lake Hovsgol. The third taxon has been identified as Fragilaria polonica Witak et Lange‐Bertalot and it is transferred to the genus Pseudostaurosira (Grunow) D. M. Williams et Round as Pseudostaurosira polonica (Witak et Lange‐Bertalot) Morales et M. B. Edlund comb. nov. based on the ultrastructural features of its valves. The relationship of the above taxa to others reported in the literature is included herein, and the nomenclatural transfer, Pseudostaurosira naveana (Le Cohu) Morales et M. B. Edlund comb. nov., is proposed.     

Allozyme and morphological observations on Festuca hyperborea, compared with F. baffinensis and F. brachyphylia (Poaceae) from the Canadian Arctic

Phenotypic plasticity in the size of leaf cross sections and in the visibility of trichomes on the leaf abaxial surface for a plant of Festuca hyperborea grown in different microhabitats is illustrated. Isozyme analyses indicate that tetraploid F. hyperborea from the Canadian Arctic is not likely a variant of tetraploid F. baffinensis and probably not a recent ancestor of the hexaploid F. brachyphylia . Although 10 populations were collected in the Canadian Arctic Archipelago as morphologically intermediate between Festuca species, with F. hyperborea considered a possible parent, no isozyme evidence suggested that this species hybridizes with either F. baffinensis or F. brachyphylia . Within plants sampled as F. hyperborea , 12 isozymatically distinct plants and one hybrid plant between this group and F. hyperborea were found.     

Bacterial dynamics in first year sea ice and underlying seawater of Saroma-ko Lagoon (Sea of Okhotsk, Japan) and resolute passage (High Canadian Arctic): inhibitory effects of ice algae on bacterial dynamics

The seasonal development of bacterial abundance in first year bottom ice and underlying seawater were studied at Saroma-ko Lagoon in Hokkaido, Japan, and at Resolute Passage in the High Canadian Arctic during the algal bloom in spring 1992. The aim of this study was to evaluate whether the high algal concentrations reached during the bloom of ice algae have inhibitory effects on bacterial dynamics. Bacterial abundance (measured as total cell count and colony-forming units CFU) increased with the increase of the algal biomass up to 500 micrograms Chla.L-1 in both locations. Culturable fraction (measured as the percentage of CFU counts versus the total cell counts) was between 7% and 22% at Saroma-ko, and approximately 0.08% at Resolute Passage. When algal biomass exceeded 500 micrograms of Chla.L-1, both bacterial abundance and culturable fraction decreased significantly. There was a maximum threshold of algal biomass (between 500 and 800 micrograms of Chla.L-1) after which bacterial dynamics become negatively coupled to the algal biomass. These results suggest that bactericidal and/or bacteriostatic compounds from these extremely high algal concentrations could explain the decrease in bacterial abundance and culturability in bottom ice observed after the ice algae bloom.     

A taxonomic and morphological review of the genus Cania Walker, 1855 (Lepidoptera,Limacodidae)

Based on a complex study of morphology of adults, male and female genitalia, functional musculature of male genitalia, and molecular characters, three subgenera were distinguished in the genus Cania: the nominative one, Paracania Solovyev subgen. n. (type species Neaera bilinea Walker, 1855), and Minicania Solovyev subgen. n. (type species C. minuta Holloway, 1986). The genus Cania presently includes 21 species, two of which are described as new ones: C. (Paracania) lourensi Solovyev sp. n. (Philippines: Luzon, Negros, Panay) and C. (Minicania) kitchingi Solovyev sp. n. (Thailand). New synonymies are established: C. bilinea (Walker, 1855) = C. polyhelixa Wu et Fang, 2009 syn. n. and C. robusta Hering, 1931 = C. pseudobilinea Wu et Fang, 2009 syn. n.     

Morphology and ultrastructure of teratological forms of the diatoms Stephanodiscus niagarae and S. parvus (Bacillariophyceae) from Hamilton Harbour (Lake Ontario,Canada)

Teratological forms of Stephanodiscus niagarae Ehrenb. and S. parvus Stoermer & Håkansson were observed during a study of diatoms preserved in a radiometrically dated core from Hamilton Harbour (Lake Ontario, Canada). Morphological features and ultrastructures of both species were studied under the light and scanning electron microscope. The valve structure of abnormal forms of S. niagarae appears to be weakly silicified, especially in the central area. The shape of satellite pores are very irregular in comparison with the round shape of the normal specimen. The central fultoportulae are characterized as small tubes extending out of the external valve. Two types of abnormal frustules are present in the population of S. parvus studied. In one type valves are underdeveloped and only the siliceous layer and ribs are present, and in the other type the valves are strongly silicified and the areolae are almost completely occluded.The teratological forms of both species appeared in the core sediments after 1911, and both became the dominant components of diatom assemblages after 1970. Their occurrence and increased abundance coincides with records of heavy metal pollution in the harbour.     

A statistical morphological analysis and taxonomic revision of the genus Xiphophora (Fucaceae)

RICE, E. L., 1989. A statistical morphological analysis and taxonomic revision of the genus Xiphophora (Fucaceae). Xiphophora is a brown seaweed endemic to the cool temperature rocky shores of Australia and New Zealand. The two species, X. chondrophylla and X. gladiata have previously been separated by morphological criteria. However, the differences betweeen them in these characters were largely size-related, resulting in taxonomic confusion. In particular, the presence of X. gladiata in New Zealand has been disputed. In this study, a series of discriminant function analyses were performed, based on a suite of morphological characters collected from each species throughout a major portion of their geographic ranges. The results show conclusively that the present taxonomy of Xiphophora is untenable. This genus is composed of two species, but these are distributed latitudinally (either side of the 40^oS parallel). Each species contains two allopatric subspecies; one in Australia and the other in New Zealand. A formal taxonomic revision of the genus is presented.     

High resolution microarray assay for rapid taxonomic assessment of Pseudo-nitzschia spp. (Bacillariophyceae) in the field

Deployable methods facilitating rapid microbial identification provide opportunities to respond quickly when pathogenic or toxin-producing organisms threaten water quality. We developed a microarray assay to streamline identification of microorganisms in the field, focusing on the harmful algal bloom diatom Pseudo-nitzschia. The assay employed electrochemical signal detection and a simplified protocol, allowing identification of specific taxa onboard research vessels within 7 h of water collection. Microarrays targeted the internal transcribed spacer (ITS1) region between the 18S and 28S ribosomal RNA genes using 307 oligonucleotide probes. The probes, ranging from broadly specific to unique, represented 118 Pseudo-nitzschia ribotypes from 15 species available at the time of assay development. Hybridization signals from multiple probes for each target strain were integrated using a novel algorithm for data analysis. Designated the ‘integrated sumscore data analysis’ (ISDA), the algorithm used probe specificity metrics for signal integration, with uniqueness corresponding to higher probe weight values. The integrated signals provided a ‘sumscore’ for each ribotype represented on the array, indicating its presence or absence in the sample. The algorithm was ‘trained’ by comparison with data from scanning electron microscopy, and cloning and sequence analysis of Pseudo-nitzschia ITS1 ribotypes from 7 laboratory cultures and a complex environmental sample. The ISDA provided correct identification and target sequences for all tested strains. Through design of custom probes (up to 12,000 on a microarray chip), this approach may be used to identify additional microbial taxa of interest and provides rapid, reliable shipboard assays for basic research or water quality monitoring.     

Ecology and morphological variability of Aulacoseira granulata (Bacillariophyceae) in Spanish reservoirs

The ecology of Aulacoseira (formerly Melosira) granulata andits different forms in     

Observations of the morphology of some known and new fragilarioid diatoms (Bacillariophyceae) from rivers in the USA

Morphological studies at the light microscopy and scanning electron microscopy levels of selected fragilarioid diatoms occurring in North American streams and lakes are presented herein. The majority of the samples studied were collected by the US Geological Survey's National Water Quality Assessment Program, which concentrates on stream water quality monitoring throughout the continental USA and Hawaii. Two new species (Staurosirella confusa Morales and Punctastriata mimetica Morales) and a new forma (Pseudostaurosiropsis geocollegarum f. triradiatum Morales) are described and two new combinations (Pseudostaurosira subsalina (Hustedt) Morales and Staurosirella olden‐burgiana (Hustedt) Morales) are provided. Morphological details of an additional taxon, Staurosira construens var. binodis (Ehrenberg) Hamilton in Hamilton et al. are also presented. The taxonomic affinities of all these taxa, as well as some evolutionary aspects and ecologic characteristics, are discussed in the light of published material.     

A taxonomic study of Jamesia (Hydrangeaceae)

Jamesia (Hydrangeaceae) is endemic to western North America from the southern Rocky Mountains in southeastern Wyoming and Colorado west across the Great Basin to the southern Sierra Nevada and south through New Mexico and southeastern Arizona to Chihuahua and Nuevo León. Its distinctiveness and Oligocene fossil record suggest that it is an old genus. The genus comprises five geographically distinct taxa that can be grouped into two species. One of these,Jamesia americana, is further divided into four varieties, the second of which is new, and the fourth of which assumes a name older than that in current use:J. americana var.americana, var.zionis, var.macrocalyx, and var.rosea. The second species,J. tetrapetala, is new.     

A revised checklist of planktonic diatoms and dinoflagellates from Helgoland (North Sea,German Bight)

A checklist based on net samples taken twice weekly from 2001 until May 2003 is presented. Identification is based on observations under direct light microscopy and after taking some organisms in culture. The checklist includes 227 taxa observed at the Helgoland Reede sampling station. One hundred and thirty-two species of diatoms from 53 genera and 95 species of dinoflagellates from 35 genera have been recorded from net samples and cultures. Thirty-five diatom and 28 dinoflagellate taxa were documented in the Helgoland phytoplankton for the first time. The list does not claim to be complete, but provides an updated list of the taxa found at Helgoland and, for convenience, also includes data published for different adjacent areas.Communicated by K. Wiltshire     

Springtime coupling between ice algal and phytoplankton assemblages in southeastern Hudson Bay,Canadian Arctic

Microalgal assemblages from the bottom ice, the ice-water interface and the water column were systematically sampled from April to June 1986, in southeastern Hudson Bay (Canadian Arctic). The taxonomic similarity between samples from the three environments was assessed using a clustering procedure. There were two groups that comprised samples from both the ice-water interface and the water column, while five other groups were made of samples originating from a single environment. Taxonomic compositions of the two mixed groups suggest two types of connexion between the ice-water interface and the water column, i.e. before the phytoplankton bloom, there was seeding of the water column by ice algae and, during ice melt, interfacial algae contributed to the water column communities that were otherwise typically phytoplankton. Overall, the phytoplankton community underwent a succession from pennate to centric diatoms. Sinking rates of algae from the ice-water interface were estimated using settling columns (SETCOL). The sinking rates increased seasonally (0.4–2.7 m d^–1), which enhanced accessibility of ice-algal cells to the pelagic grazers. Ice algae contributed to water column production as they became accessible to the pelagic grazers, and also by seeding the water column before the phytoplankton bloom.Contribution to the programs of GIROQ (Groupe interuniversitaire de recherches océanographiques du Québec) and of the Maurice Lamontagne Institute (Department of Fisheries and Oceans)     

A taxonomic study of the subantarctic Piptoporus (Polyporaceae, Basidiomycetes) I

Ryvardenia gen. nov. is proposed to accommodate Polyporus cretaceus (as type species) and Polyporus campylus . The new genus is characterized by: medium to large fruit bodies that may be solitary or imbricate; monomitic context with clamped generative hyphae with thin to thickened walls that are not metachromatic in cresylblue; dimitic dissepiments with unbranched skeletal hyphae; obovate or broad-ellipsoid, uninucleated, thick walled spores; bipolar sexuality; astatocoenocytic nuclear behavior and simple-septated generative hyphae in the advancing mycelium in culture. Mating tests between specimens from Australia/New Zealand and Argentina of R. cretacea and R. campyla are presented. Tyromyces falcatus is considered a synonym of R. campyla only differing in the greater amount of sclerified generative hyphae and skeletal hyphae present in the fruit bodies.     

A taxonomic study of the Subantarctic Piptoporus (Polyporaceae, Basidiomycetes) II

Morphological and cultural studies of Polyporus maculatissimus and P. portentosus are presented. Neolentiporus gen. nov. is proposed to accommodate P. maculatissimus , a species with a striking macromorphological similarity with the north temperate P. squamosus . The new genus is characterized by medium to large stipitate fruitbodies with a poroid hymenophore, circular to flabellate pilei with a scaly surface and an excentric or lateral stipe that sometimes is reduced to a short, robust umbo. The hyphal system is dimitic with clamped, irregularly thick-walled generative hyphae that do not react with cresyl-blue, and terminal, unbranched, thick-walled skeletal hyphae that are strongly metachromatic in cresyl-blue. Spores are cylindric, hyaline, thin-walled, inamyloid and binucleate. The sexuality is bipolar, the nuclear behavior is astatocoeno-cytic and the associated wood-rot is brown. The new genus is regarded as the poroid counterpart of the agaricoid Neolentinus. Polyporus portenrosus is included in Laetiporus on the basis of its yellowish fruitbodies, its soft, punky context, its hyphal system composed of simple septate generative hyphae and binding hyphae, its holocoenocytic nuclear behavior and its associated brown wood-rot. A new code symbol, i.e. '9s' is proposed to codify the presence, in cultures, of simple-septate generative hyphae with irregularly thickened walls.     

Sea ice phenology and timing of primary production pulses in the Arctic Ocean

Arctic organisms are adapted to the strong seasonality of environmental forcing. A small timing mismatch between biological processes and the environment could potentially have significant consequences for the entire food web. Climate warming causes shrinking ice coverage and earlier ice retreat in the Arctic, which is likely to change the timing of primary production. In this study, we test predictions on the interactions among sea ice phenology and production timing of ice algae and pelagic phytoplankton. We do so using the following (1) a synthesis of available satellite observation data; and (2) the application of a coupled ice‐ocean ecosystem model. The data and model results suggest that, over a large portion of the Arctic marginal seas, the timing variability in ice retreat at a specific location has a strong impact on the timing variability in pelagic phytoplankton peaks, but weak or no impact on the timing of ice‐algae peaks in those regions. The model predicts latitudinal and regional differences in the timing of ice algae biomass peak (varying from April to May) and the time lags between ice algae and pelagic phytoplankton peaks (varying from 45 to 90 days). The correlation between the time lag and ice retreat is significant in areas where ice retreat has no significant impact on ice‐algae peak timing, suggesting that changes in pelagic phytoplankton peak timing control the variability in time lags. Phenological variability in primary production is likely to have consequences for higher trophic levels, particularly for the zooplankton grazers, whose main food source is composed of the dually pulsed algae production of the Arctic.