Jeffrey R. Johansen

Molecular and morphological characterization of ten polar and near-polar strains within the oscillatoriales (Cyanobacteria)

An approximately 1400‐bp region of the 16S rRNA gene was sequenced for 10 polar or near‐polar strains putatively placed in the Oscillatorialean genera Oscillatoria, Phormidium, and Lyngbya obtained from the University of Toronto Culture Collection to assess phylogenetic relationships. The strains were also examined for thylakoid structure and cell division type with TEM as well as traditional morphology with LM. Phylogenetic trees constructed using parsimony, distance, and maximum likelihood methods were similar in topology. If the original epithets applied to the sequenced strains (both polar and those from GenBank) were used, it was clear that taxa were not monophyletic. However, using the revised taxonomic system of Anagnostidis and Komárek, we were able to reassign these strains to their current correct taxa (species, genus, and family). When these assignments were made, it was determined that the molecular sequence data analyses were congruent with morphology and ultrastructure. Nine of the polar strains were found to be new species, and eight were described as such: Arthronema gygaxiana Casamatta et Johansen sp. nov., Pseudanabaena tremula Johansen et Casamatta sp. nov., Leptolyngbya angustata Casamatta et Johansen sp. nov., Phormidium lumbricale Johansen et Casamatta sp. nov., Microcoleus glaciei Johansen et Casamatta sp. nov., Microcoleus rushforthii Johansen et Casamatta sp. nov., Microcoleus antarcticus Casamatta et Johansen sp. nov., Microcoleus acremannii Casamatta et Johansen sp. nov. Some genera (Leptolyngbya and Microcoleus) were clearly not monophyletic and require future revision.

Phylogeny and Genetic Variance in Terrestrial Microcoleus (Cyanophyceae) Species Based on Sequence Analysis of the 16S rRNA Gene and Associated 16S-23S ITS Region.

Thirty‐one strains of Microcoleus were isolated from desert soils in the United States. Although all these taxa fit the broad definition of Microcoleus vaginatus (Vaucher) Gomont in common usage by soil algal researchers, sequence data for the 16S rRNA gene and 16S–23S internal transcribed spacer (ITS) region indicated that more than one species was represented. Combined sequence and morphological data revealed the presence of two morphologically similar taxa, M. vaginatus and Microcoleus steenstrupii Boye‐Petersen. The rRNA operons of these taxa were sufficiently dissimilar that we suspect the two taxa belong in separate genera. The M. vaginatus clade was most similar to published sequences from Trichodesmium and Arthrospira. When 16S sequences from the isolates we identified as M. steenstrupii were compared with published sequences, our strains grouped with M. chthonoplastes (Mertens) Zanardini ex Gomont and may have closest relatives among several genera in the Phormidiaceae. Organization within the 16S–23S ITS regions was variable between the two taxa. Microcoleus vaginatus had either two tRNA genes (tRNAIle and tRNAAla) or a fragment of the tRNAIle gene in its ITS regions, whereas M. steenstrupii had rRNA operons with either the tRNAIle gene or no tRNA genes in its ITS regions. Microcoleus vaginatus showed no subspecific variation within the combined morphological and molecular characterizations, with 16S similarities ranging from 97.1% to 99.9%. Microcoleus steenstrupii showed considerable genetic variability, with 16S similarities ranging from 91.5% to 99.4%. In phylogenetic analyses, we found that this variability was not congruent with geography, and we suspect that our M. steenstrupii strains represent several cryptic species.

COLEOFASCICULUS GEN. NOV. (CYANOBACTERIA): MORPHOLOGICAL AND MOLECULAR CRITERIA FOR REVISION OF THE GENUS MICROCOLEUS GOMONT 1

Species currently classified within the cyanobacterial genus Microcoleus were determined to fall into two distinct clades in a 16S rDNA phylogeny, one containing taxa within the Oscillatoriaceae, the other containing taxa within the Phormidiaceae. The two lineages were confirmed in an analysis of the 16S–23S internal transcribed spacer (ITS) region sequences and secondary structures. The type species for Microcoleus is M. vaginatus Gomont, and this taxon belongs in the Oscillatoriaceae. Consequently, Microcoleus taxa in the Phormidiaceae must be placed in separate genera, and we propose the new genus Coleofasciculus to contain marine taxa currently placed in Microcoleus. The type species for Coleofasciculus is the well‐studied and widespread marine mat‐forming species Microcoleus chthonoplastes (Mert.) Zanardini ex Gomont. Other characters separating the two families include type of cell division and thylakoid structure.

Recovery Patterns of Cryptogamic Soil Crusts in Desert Rangelands Following Fire Disturbance

The effects of fire on cryptogamic soil crust communities at Camp Floyd State Park, Utah, were examined. Three years after fire, lichen and moss cover were both substantially lower in abundance in the burned area than in the adjacent unburned area. Both the living algae, as measured by culture techniques, as well as the subfossil diatom commi nity, which was measured directly, were also significantly lower in the burned area. Two years later, the algae had shown considerable recovery. Only one group of algae, the chrysophyte cysts observed in the subfossil diatom slides, was significantly lower in the burned area at this time. Though invasion of lichens and mosses had begun after five years, recovery was not complete either in terms of biomass or composition at the conclusion of the study. Factors contributing to the recovery of the crusts ap- parently included above average precipitation over the last few years, proximity and type of prop- agules, and protection from subsequent disturbance.

Morphological and molecular characterization of selected desert soil cyanobacteria: three species new to science including Mojavia pulchra gen. et sp. nov.

K. Řeháková, J.R. Johansen, D.A. Casamatta, L. Xuesong and J. Vincent. 2007. Morphological and molecular characterization of selected desert soil cyanobacteria: three species new to science including Mojavia pulchra gen. et sp.nov. Phycologia 46: 481–502. DOI: 10.2216/06-92.1 Four Nostocacean species from desert soils of the western United States, including the phycobiont of the lichen Collema tenax, were studied. Our strains could be forced into morphospecies previously described from Europe, but phylogenetic analysis indicated that they belonged in separate, distinct, and previously undescribed taxa. Partial 16S rRNA sequences of the strains CM1-VF10, CM1-VF14, CNP-AK1 and JT2-VF2 were determined and aligned with published Nostoc sequences from GenBank and our lab, as well as other Nostocales. All aligned sequences were analysed using parsimony, distance, and maximum likelihood methods, and trees based on three separate data sets were generated. Full 16S-23S internal transcribed spacer (ITS) regions were also characterized for our strains, and secondary structures of the ITS region were compared among these and N. commune and N. punctiforme. Intragenomic variability was documented among ITS regions in different operons for these taxa. One of the four strains (JT2-VF2) is distinct from Nostoc by both morphological and molecular criteria and is described as Mojavia pulchra gen. et sp. nov. Two other strains (CM1-VF10 and CM1-VF14) are described as Nostoc indistinguendum sp. nov. and Nostoc desertorum sp. nov., respectively. According to both morphological and molecular characteristics, the phycobiont of C. tenax is not N. commune, N. sphaericum or N. punctiforme as variously suggested in the lichenological literature, and the older name for this taxon, Nostoc lichenoides, is consequently validated in this paper.

Spirirestis rafaelensis gen. et sp. nov. (Cyanophyceae), a new cyanobacterial genus from arid soils

A new cyanobacterial genus and species, Spirirestis rafaelensis , is described from soils of a semi-arid Utah juniper community in the San Rafael Swell, Utah, U.S.A. Multiple isolates of the organism have only been recovered from well-crusted, protected, and totally undisturbed soils at this site; it has not been recovered from any of the other 40 sites we have examined in the Sonoran, Mojave, Chihuahuan, Colorado Plateau, or Great Basin deserts during the last eight years. Spirirestis shares morphological characters with members of both the Scytonemataceae and Microchaetaceae, principally heterocyte formation, false branching, and presence of sheath. However, unlike the trichomes of all previously described genera in these families, most trichomes of Spirirestis are tightly spiraled. 16S rRNA sequence data suggest that Spirirestis is more closely related to members of the Microchaetaceae than to members of the Scytonemataceae or Rivulariaceae. The data also support the maintenance of Microchaetaceae and Scytonemataceae as separate families.

Recognizing cyanobacterial diversity through adoption of a new species paradigm

In order to recognize the extent of biodiversity in the cyanobacteria, we need to adopt species concepts that will provide theoretical rigor and pragmatic criteria for de- scribing increased numbers of taxa as polyphasic data on cyanobacteria become avail- able. We reject phenetic (similarity) based species concepts, as these are incorrect by modern systematic standards. The Biological Species Concept is also rejected as it does not apply to asexual organisms. Four phylogenetic species concepts seem to be good can- didate constructs for the cyanobacteria: 1) the Evolutionary Species Concept, 2) the Eco- typic Species Concept, 3) the Phylogenetic Species Concept, and 4) the Monophyletic Species Concept. Of these, we consider the Monophyletic Species Concept to be the most theoretically sound and pragmatic when molecular sequence data for phylogenetic analy- sis are available. The Ecotypic Species Concept is appropriate when molecular data are not available, and only morphology and ecology are known.

A unique pseudanabaenalean (cyanobacteria) genus Nodosilinea gen. nov. based on morphological and molecular data

The cyanobacteria are a diverse, ancient lineage of oxygenic, phototrophic bacteria. Ubiquitous in nearly all ecosystems, the alpha‐level diversity of these organisms lags behind other algal lineages due to a perceived dearth of phylogenetically useful characters. Recent phylogenetic studies of species within the genus Leptolyngbya have demonstrated that this is a polyphyletic assemblage. One group of strains that fits within the current circumscription of Leptolyngbya is genetically and phylogenetically distinct from Leptolyngbya sensu stricto. Members of this clade possess both a morphological synapomorphy and shared 16S‐23S internal transcribed spacer (ITS) secondary structure, allowing the diagnosis of the new cyanobacterial genus Nodosilinea. Members of this genus are united by the unique ability to form nodules along the length of the filament. This trait has been previously observed only in the species Leptolyngbya nodulosa Z. Li et J. Brand, and we have chosen this species as the generitype of Nodosilinea. We currently recognize four species in the genus, N. nodulosa (Z. Li et J. Brand) comb. nov., N. bijugata (Kong.) comb. nov., N. conica sp. nov., and N. epilithica sp. nov.

Effects of long-term grazing on cryptogam crust cover in Navajo National Monument, Arizona.

The effects of long-term grazing (40 years) on cryptogamic crusts of Navajo National Monument were investigated. Both vascular and nonvascular communities were heavily impacted with the cryptogamic community showing the greatest reduction in cover. Lichens and mosses were the most damaged, while the algae were much more tolerant. Individual cryptogamspeeies were affected in similar patterns with all identifuble species showing reduced cover. Vascuhr plant species were also affected with grassesshowing the greatest reduction under grazing pressure. Throughout desert systems of western North America there is scant ground cover and often extensive open areas between the plants. In such open areas, soils are exposed to powerful erosive impacts. When soils are unprotected, erosion can be extensive and soil losses can be great. Of primary importance in the protection of desert soils are communities of nonvascular cryptogamic plants that grow upon or immediately beneath the soil surface. When well established and undisturbed such plants form a crust which plays an important role in soil stabilization (Fletcher and Martin 1948; Kleiner and Harper 1972, 1977; Loope and Gifford 1972; Anderson et al. 1982a, 1982b). Algae are the primary components of these crusts but they are often accompanied by lichens and mosses (Anderson and Rushforth 1977, Kleiner and Harper 1972). Algae are the most effective in binding the soil particles (Anantani and Marathe 1974, Anderson and Rushforth 1976). Where cryptogam crusts are well developed the soil surface is almost always highly stable. Research has been done on several aspects of the biology of soil crusts and cryptogamic communities. Ecological relationships have been studied by Anderson et al. (1982a) and Anderson et al. (1982b). Species composition and taxonomic relationships of crusts were studied by Anderson and Rushforth (1976). The role of such crusts in nitrogen fixation was studied by Rychert and Skujins (1974) and their effects on infiltrationand sedimentation by Loope and Gifford (1972). However, much is yet to be learned about the role of these crusts in desert ecosystems. The Navajo National Monument boundary (fenceline) provided an excellent opportunity to evaluate the effects of grazing on the cryptogamic soil crusts of the pinyon-juniper zone in northeastern Arizona. The objective of this study was to evaluate the effects of long-term grazing (40 years) on the cryptogamic soil cover of the pinyon-juniper zone in northern Arizona (Navajo National Monument).

FRESHWATER DIATOMS FROM CAROLINA BAYS AND OTHER ISOLATED WETLANDS ON THE ATLANTIC COASTAL PLAIN OF SOUTH CAROLINA, U.S.A., WITH DESCRIPTIONS OF SEVEN TAXA NEW TO SCIENCE

This study represents the first taxonomic and ecological description of the diatom flora of Carolina bays, the most abundant, natural lentic systems on the Atlantic Coastal Plain of the United States. Diatoms were collected from surface sediments and benthic and planktonic microhabitats in Carolina bays and other isolated wetland ponds in South Carolina during three seasons to survey the extant flora and document habitat affinities. The ponds ranged from marshes and grass/sedge meadows to forested swamps and were prone to episodic drying. All were acidic, dystrophic and nutrient-poor. At the generic level, diatom assemblages resembled those of other acidic, shallow ponds, being dominated by Eunotia, Pinnularia, Frustulia and Neidium. Diatom assemblages were distinct from neighboring lotic and reservoir systems, and contained several taxa new to science. Considerable variation in diatom assemblage composition among ponds was attributable, in part, to differences in susceptibility of the ponds to drying. In basins that dry frequently, aerophilic taxa such as Orthoseira dendroteres (Ehrenberg) Crawford, Pinnularia borealis var. scalaris (Ehrenberg) Rabhenhorst and Luticola saxophila (Bock ex Hustedt) Mann were common. Permanent pond assemblages were dominated by species of Frustulia, Tabellaria and Stenopterobia. Habitat fidelity was low; most taxa were associated with a diversity of substrates and did not exhibit marked seasonality. Substrate and seasonal associations are given for taxa with notable affinities. Taxonomic descriptions are provided for Eunotia pocosinensis sp. nov., Eunotia sarraceniae sp. nov., Stauroneis anceps var. subrostrata var. nov., Pinnularia turfosiphila sp. nov., Pinnularia bigibba sp. nov., Pinnularia subgibba var. gracilis var. nov. and Pinnularia subgibba var. lanceolata var. nov.