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Reproductive characteristics are important for defining taxonomic groups of filamentous Zygnematophyceae, but they have not been fully observed in the genus Zygogonium. Specimens of Z. ericetorum previously studied and used to clarify the generic concept lacked fertile material, which was obtained recently. This study illustrates for the first time, using color light microscopic and fluorescence images, a consequent conjugation stage in Z. ericetorum, including completely developed zygospores and purple cytoplasmic residue content left outside the zygospores, similar to aplanospore formation. Structures confirmed earlier reports and provided new observation informative regarding phylogenetically relevant reproductive characters of Z. ericetorum. [ABSTRACT FROM AUTHOR]

Zygogonium ericetorum, the type species of the genus, was studied from a natural population collected in Mt. Schönwieskopf, Tyrol, Austria. Generic concepts of Zygogonium and Zygnema were tested with atpB, psbC, and rbcL gene sequence analysis, which showed a sister relationship between Z. ericetorum and Mesotaenium, in an early branching clade sister to a grouping of Zygnema and several other filamentous and unicellular zygnematalean taxa. A variety of light, confocal, transmission electron microscopy, and cytochemical techniques provided new data on the variable chloroplast shape of Z. ericetorum, and its aplanospore structure and development, which has been previously considered taxonomically important but has been ambiguously interpreted. Zygogonium can be distinguished from other zygnematophytes (particularly Zygnema), based on the combination of two characters: (i) irregular, compressed plate-like chloroplasts and (ii) residual cytoplasmic content left in sporangia outside of the fully developed aplanospores or zygospores. The presence of a sporangial wall that separates the spores from the parent cell should be excluded from the definition of Zygogonium, because it is also observed in Zygnema. Similarly, the ecological characterization of Zygogonium as acidophilic is not unique to the genus. The names of 18 species currently belonging to Zygogonium are here changed to Zygnema, because of incompatibility with this new proposed Zygogonium concept. In the species transferred to Zygnema, chloroplasts are typically stellate in three-dimensions, and the entire content of fertile cells is transformed into the spore, so there is no cytoplasmic residue. [ABSTRACT FROM AUTHOR]

Diversity of the filamentous green algae in the genus Spirogyra (Zygnematophyceae) was investigated from more than 1,200 stream samples from California. We identified 12 species of Spirogyra not previously known for California ( CA), including two species new to science, Spirogyra californica sp. nov. and Spirogyra juliana sp. nov. Environmental preferences of the Californian species are discussed in the light of their restricted distribution to stream habitats with contrasting nutrient levels. We also investigated the systematic relationships of Spirogyra species from several continents using the chloroplast-encoded genes ribulose-1,5-bisphosphate carboxylase/hydrogenase large subunit ( rbcL) and the beta subunit of the ATP synthase ( atpB). Californian species were positioned in most major clades of Spirogyra. The phylogeny of Spirogyra and its taxonomic implications are discussed, such as the benefits of combining structural and molecular data for more accurate and consistent species identification. Considerable infraspecific genetic variation of globally distributed Spirogyra species was observed across continental scales. This finding suggests that structurally similar species from distant regions may be genetically dissimilar and that Spirogyra may contain a large number of cryptic species. Correlating the morphological and genetic variation within the genus will be a major challenge for future researchers. [ABSTRACT FROM AUTHOR]

Natural populations of Zygnema were collected from 80 stream sites across California, and eight species were identified and characterized morphologically. Generic and infrageneric concepts of Zygnema and Zygogonium were tested with cox3 and rbcL gene sequence analysis. Strains of Zygnema were positioned in a single monophyletic clade sister to Zygogonium tunetanum Gauth.-Lièvre. In both the rbcL and cox3 phylogenies, strains of Zygnema formed two major clades. The first clade contained species that have zygospores with a blue-colored mesospore or akinetes with a colorless mesospore. The second clade contained species that have a yellow or brown mesospore. The existing taxonomic concepts for Zygnema classification are not consistent with our molecular phylogeny and do not correspond to natural groups. We propose that mesospore color may be useful in the infrageneric classification of Zygnema. Newly described Zygnema aplanosporum sp. nov. and Zygnema californicum sp. nov. have zygospores with a blue mesospore formed in the conjugation tube and separated by a cellulosic sporangial wall. Z. aplanosporum also possessed a combination of vegetative and reproductive features characteristic of Zygogonium, such as presence of short branches, rhizoidal outgrowths, thickened vegetative cell walls, purple-colored cell content, small compressed-globular chloroplasts as well as predominant asexual reproduction. Z. aplanosporum and Z. californicum were deeply embedded in a larger clade of Zygnema both in rbcL and cox3 analyses. Based on our observations, there are no features or combination of features that separate Zygnema and Zygogonium. Therefore, we conclude that Zygogonium is probably a synonym of Zygnema. [ABSTRACT FROM AUTHOR]

Natural populations of Zygnema were collected from 80 stream sites across California, and eight species were identified and characterized morphologically. Generic and infrageneric concepts of Zygnema and Zygogonium were tested with cox3 and rbcL gene sequence analysis. Strains of Zygnema were positioned in a single monophyletic clade sister to Zygogonium tunetanum Gauth.-Lièvre. In both the rbcL and cox3 phylogenies, strains of Zygnema formed two major clades. The first clade contained species that have zygospores with a blue-colored mesospore or akinetes with a colorless mesospore. The second clade contained species that have a yellow or brown mesospore. The existing taxonomic concepts for Zygnema classification are not consistent with our molecular phylogeny and do not correspond to natural groups. We propose that mesospore color may be useful in the infrageneric classification of Zygnema. Newly described Zygnema aplanosporum sp. nov. and Zygnema californicum sp. nov. have zygospores with a blue mesospore formed in the conjugation tube and separated by a cellulosic sporangial wall. Z. aplanosporum also possessed a combination of vegetative and reproductive features characteristic of Zygogonium, such as presence of short branches, rhizoidal outgrowths, thickened vegetative cell walls, purple-colored cell content, small compressed-globular chloroplasts as well as predominant asexual reproduction. Z. aplanosporum and Z. californicum were deeply embedded in a larger clade of Zygnema both in rbcL and cox3 analyses. Based on our observations, there are no features or combination of features that separate Zygnema and Zygogonium. Therefore, we conclude that Zygogonium is probably a synonym of Zygnema. [ABSTRACT FROM AUTHOR]

The systematics of the Prasiolales was investigated by phylogenetic inference based on analyses of the rbcL and 18S rRNA genes for representatives of all four genera currently attributed to this order ( Prasiococcus, Prasiola, Prasiolopsis, Rosenvingiella), including all type species. The rbcL gene had higher sequence divergence than the 18S rRNA gene and was more useful for phylogenetic inference at the ranks of genus and species. In the rbcL gene phylogeny, three main clades were observed, corresponding to Prasiola, Prasiolopsis, and Rosenvingiella. Prasiococcus was nested among species of Prasiola occurring in subaerial and supralittoral habitats. Trichophilus welckeri Weber Bosse, a subaerial alga occurring in the fur of sloths in Amazonia, was closely related to Prasiolopsis ramosa Vischer. The species of Prasiola were grouped into three well-supported clades comprising (i) marine species, (ii) freshwater and terrestrial species with linear blades, and (iii) terrestrial species with rounded or fan-shaped blades. Sequence divergence was unexpectedly low in the marine group, which included species with different morphologies. For the 18S rRNA gene, the phylogenetic analyses produced several clades observed for the rbcL gene sequence analysis, but, due to very little sequence variation, it showed considerably lower resolution for inference at the species and genus levels. Due to the low support of some internal branches, the results of the analyses did not allow an unambiguous clarification of the origin and the early evolution of the Prasiolales. [ABSTRACT FROM AUTHOR]

Previous phylogenetic studies of the Rhodophyta have provided a framework for understanding red algal phylogeny, but there still exists the need for a comprehensive analysis using a broad sampling of taxa and sufficient phylogenetic information to clearly define the major lineages. In this study, we determined 48 sequences of the PSI P700 chl a apoprotein A1 ( psaA) and rbcL coding regions and established a robust red algal phylogeny to identify the major clades. The tree included most of the lineages of the Bangiophyceae (25 genera, 48 taxa). Seven well-supported lineages were identified with this analysis with the Cyanidiales having the earliest divergence and being distinct from the remaining taxa; i.e. the Porphyridiales 1–3, Bangiales, Florideophyceae, and Compsopogonales. We also analyzed data sets with fewer taxa but using seven proteins or the DNA sequence from nine genes to resolve inter-clade relationships. Based on all of these analyses, we propose that the Rhodophyta contains two new subphyla, the Cyanidiophytina with a single class, the Cyanidiophyceae, and the Rhodophytina with six classes, the Bangiophyceae, Compsopogonophyceae, Florideophyceae, Porphyridiophyceae classis nov. (which contains Porphyridium, Flintiella, and Erythrolobus), Rhodellophyceae, and Stylonematophyceae classis nov. (which contains Stylonema, Bangiopsis, Chroodactylon, Chroothece, Purpureofilum, Rhodosorus, Rhodospora, and Rufusia). We also describe a new order, Rhodellales, and a new family, Rhodellaceae (with Rhodella, Dixoniella, and Glaucosphaera). [ABSTRACT FROM AUTHOR]

A previous study of the North American biogeography of the red algal genusHildenbrandianoted the presence of group I introns in the nuclear small subunit (SSU) rRNA gene of the marine speciesH. rubra(Sommerf.) Menegh. Group IC1 introns have been previously reported at positions 516 and 1506 in the nuclear SSU RNA genes in the Bangiales and Hildenbrandiales. However, the presence of an unclassified intron at position 989 in a collection ofH. rubrafrom British Columbia was noted. This intron is a member of the IE subclass and is the first report of this intron type in the red algae. Phylogenetic analyses of the intron sequences revealed a close relationship between this IE intron inserted at position 989 and similar fungal IE introns in positions 989 and 1199. The 989 IE introns formed a moderately to well-supported clade, whereas the 1199 IE introns are weakly supported. Unique structural helices in the P13 domain of the 989 and 1199 IE introns also point to a close relationship between these two clades and provide further evidence for the value of secondary structural characteristics in identifying homologous introns in evolutionarily divergent organisms. The absence of the 989 IE intron in all other red algal nuclear SSU rRNA genes suggests that it is unlikely that this intron was vertically inherited from the common ancestor of the red algal and fungal lineages but rather is the result of lateral transfer between fungal and red algal nuclear SSU rRNA genes. [ABSTRACT FROM AUTHOR]

The only known population ofBatrachospermum spermatiophorumVisetSheath, located in a small stream on east Maui, Hawaii, was sampled from November 2001 to October 2002 to investigate its phenology. Additionally, the taxonomic status of the alga was examined. Phylo­genetic analyses of the large subunit of the ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) gene forB. spermatiophorumconfirm its placement within the SectionContortaof the genusBatrachospermum. Comparisons withrbcL gene sequences for all other availableBatrachospermumspecies, including 10 other members of the SectionContorta, illustrate thatB. spermatiophorumis distinct in itsrbcL nucleotide sequence and should be maintained as a separate species. The phenology ofB. spermatiophorumdiffered from most studies ofBatrachospermumreproduction in that the gametophytes were present year round, and no macroscopic chantransia stages were identified at any point during the present study. Maximum plant length was highest in the late fall and early winter months, while gametangial production peaked in February and March. Carposporophyte abundance rose sharply in July and August, and the percentage of carposporophytes producing carpospores was highest in late summer and early fall months. Although significant correlations were determined among stream conditions and among phenological characteristics, only pH was associated with several of the reproductive characters, which is unusual for studies ofBatrachospermumphenology. Timing of sexual reproduction for all macroalgal community members in the stream site was not coordinated, with some reproducing year round and others more sporadically. The year-round presence ofBatrachospermumgametophytes may be a result of a combination of smaller seasonal changes in cues such as day length and water temperature in the tropical environment than occur in temperate locations, and lack of extreme conditions that might inhibit the persistence of the gametophyte. [ABSTRACT FROM AUTHOR]

Fifty-seven collections of marine and freshwater Hildenbrandia from North America, South America, Europe, and Africa were compared with 21 type and historically important specimens using multivariate morphometrics. Additionally, phylogenetic analyses of 48 specimens of Hildenbrandia and two specimens of Apophlaea were carried out based on sequences of the rbc L chloroplast gene and the nuclear 18S rRNA gene. Morphometric analyses based on vegetative cell and filament dimensions distinguished two groups of freshwater Hildenbrandia specimens, the first corresponding to those collections from North America and the Philippines and the second to those from Europe and the Canary Islands. The first group had smaller mean cell and filament dimensions (cells 4.0 × 4.4 μm, filaments 46.5 μm) and corresponded to H. angolensis , whereas the second group had larger mean dimensions (cells 5.8 × 6.6 μm, filaments 55.3 μm) and represented H. rivularis. Marine specimens were morphometrically distinguishable into two groups based on tetrasporangial division pattern as well as other thallus characters. However, measurements and character determinations of some type specimens differed greatly from the original descriptions, and thus further work to determine the stability of these characters is required. Phylogenetic reconstruction based on the 18S rRNA gene and rbc L gene sequence data generally demonstrated separation of the marine and freshwater forms of Hildenbrandia , with some marine taxa forming monophyletic groups (e.g. H. lecannellieri and H. occidentalis ) and others forming paraphyletic groups (e.g. H. rubra ). The two specimens of Apophlaea formed a monophyletic group within the paraphyletic genus Hildenbrandia. [ABSTRACT FROM AUTHOR]

Fifty-seven collections of marine and freshwater Hildenbrandia from North America, South America, Europe, and Africa were compared with 21 type and historically important specimens using multivariate morphometrics. Additionally, phylogenetic analyses of 48 specimens of Hildenbrandia and two specimens of Apophlaea were carried out based on sequences of the rbc L chloroplast gene and the nuclear 18S rRNA gene. Morphometric analyses based on vegetative cell and filament dimensions distinguished two groups of freshwater Hildenbrandia specimens, the first corresponding to those collections from North America and the Philippines and the second to those from Europe and the Canary Islands. The first group had smaller mean cell and filament dimensions (cells 4.0 × 4.4 μm, filaments 46.5 μm) and corresponded to H. angolensis , whereas the second group had larger mean dimensions (cells 5.8 × 6.6 μm, filaments 55.3 μm) and represented H. rivularis. Marine specimens were morphometrically distinguishable into two groups based on tetrasporangial division pattern as well as other thallus characters. However, measurements and character determinations of some type specimens differed greatly from the original descriptions, and thus further work to determine the stability of these characters is required. Phylogenetic reconstruction based on the 18S rRNA gene and rbc L gene sequence data generally demonstrated separation of the marine and freshwater forms of Hildenbrandia , with some marine taxa forming monophyletic groups (e.g. H. lecannellieri and H. occidentalis ) and others forming paraphyletic groups (e.g. H. rubra ). The two specimens of Apophlaea formed a monophyletic group within the paraphyletic genus Hildenbrandia. [ABSTRACT FROM AUTHOR]

Representatives of the freshwater red algal family Thoreaceae were studied to resolve their taxonomic and phylogenetic status. Three specimens of Nemalionopsis and five collections of Thorea were examined for pit plug ultrastructure and analyzed for the sequences of the genes coding for the large subunit of RUBISCO (rbc L) and the small subunit of rRNA (18S rRNA). The phylogenetic trees generated from the two genes, and a combined tree all showed the Thoreaceae to be contained in a well-supported monophyletic clade that is separate from the other two families currently classified in the Batrachospermales, the Batrachospermaceae and the Lemaneaceae. In addition, secondary structure elements of the 18S rRNA gene were observed at positions 650 and 1145 (Escherichia coli numbering system) that are not present in other members of the Rhodophyta. The pit plugs of the gametophytic and chantransia stages of the Thoreaceae contain two cap layers, the outer one of which is typically plate-like, though occasionally inflated ones have been seen. No pit plug cap membrane has been observed. These findings indicate the Thoreaceae has been misclassified in the Batrachospermales and should be placed in its own order, the Thoreales. This order is characterized by having freshwater representatives with multiaxial gametophytes, a uniaxial chantransia stage, and pit plugs with two cap layers, the outer one of which is usually plate-like. [ABSTRACT FROM AUTHOR]

Presents a study which sequenced the nuclear small subunit (SSU) ribosomal DNA (rDNA) coding region of Bangiophycidae and Florideophycidae to gain insights into algae evolution. Materials and methods used; Analyses of the phylogeny of the concatenated nuclear and plastid SSU rDNA; Characteristics of bangiophytes.

SUMMARYThe development and release of the unique vegetative propagules of the freshwater encrusting alga Hildenbrandia angolensis Welwitsch ex West et West, gemmae, were studied using several different microscopic and histochemical techniques. In addition, the seasonality of gemma production was monitored bimonthly over a 12-month period in two spring-fed streams in Texas, USA. Gemmae differentiate within the thallus and are subsequently released from the surface of the crust. Release of the gemmae most likely occurs by digestion of surrounding cells, as suggested by the presence of starch granules and lipid globules in the region between the released gemma and the thallus. The initial separation of the gemmae from the thallus occurs from the sides of the gemma or the bottom, or possibly simultaneously. Contrary to previous studies, we have observed that gemma production occurs endogenously within the thallus of freshwater Hildenbrandia, rather than on the surface of the crust in raised structures. Histochemical tests and electron microscopic examination indicate that the cells of the gemmae contain a large amount of floridean starch. The starch granules frequently form rings surrounding the nuclei of both gemma and thallus cells; a feature infrequently reported for florideophyte red algae. Our seasonality investigations indicate that large fluctuations in gemma production occur over 1 year, but at least some gemma production continues year-round in the streams examined. [ABSTRACT FROM AUTHOR]

Analyzes unialgal cultures and field collections of the rhodophyte Balbiana investiens Sirodot in terms of their morphology, ultrastructure and the DNA sequences of the genes coding for the large subunit of ribulose-1,5-biphosphate carboxylase/oxygenase and 18S ribosomal RNA. Distinguishing features of the species; Identical sequences for all regions of DNA analyzed by the two specimens of Balbiana from England and Germany.

Fifteen populations of the widespread freshwater red alga Batrachospermum gelatinosum (L.) De Candole were sampled throughout the geographic range in North America from central Alabama, U.S.A. (33°N) to Ellesmere Island, Nrothwest Terriotories (NWT), Canada (80°N). Analysis of ribosomal DNA internal transcribed spacer (TTS) 1 and 2 sequences yielded a parsimony tree with a large polytomy consisting of most populatins plus a branch with one Nava Scotia and two NWT populations. The nucleotide vatioation, both within the polytomy and within the branch, was small (<1%). The sequence divergence between the branch and polytomy was 3%. The lengths of the ITS 1 and 2 sequences of B. gelatinosum, 216-229 and 448-458 base pairs, respectively, fall within the very broad ranges reported for other red algae. The cluster analysis of 11 morphometric characteristics revealed three groupings of populations, partly based on geographic distribution. All tundra, eastern boreal forest, and Midwestern hemlock-hardwood populations were in one grouping, whereas the deciduous forestm coastal plain, and eastern hemlock-hardwood populations were in a second. However, one deciduous forest population from Rhode Island, U.S.A. was unassociated. There was considerable overlap in morphometric characteristics among the three groupings. Based on this fact and the relatively small nucleotide variation in ITS sequences, we conclude that B. gelatinosum is a morphologically variable and geographically wide-spread species that is a valid taxonomic entity. [ABSTRACT FROM AUTHOR]

Twenty-one populations of Batrachospermum section Turfosa from North America were compared to nine type and two historically important specimens using multivariate morphometrics and image analysis. The protologues of six other infrageneric taxa were also compared. From this analysis, six species are recognized worldwide: B. desikacharyi Sankaran, B. gombakense Kumano et Ratnasabapathy, B. keratophytum Bory de Saint-Vincent [syn. B. vagum var. keratophytum (Bory de Saint-Vincent) Sirodot, B. gulbenkianum Reis, and B. suevorum Kützing nom. illeg.], B. sinense Jao, B. turfosum Bory de Saint-Vincent [syn. B. vagum (Roth) C. Agardh and B. vagum var. undulato-pedicellatum Kumano et Watanabe], and B. vogesiacum F. G. Schultz ex Skuja [syn. B. vagum var. flagelliforme Sirodot, B. flagelliforme (Sirodot) Necchi]. These species are distinguished on the basis of carposporophyte-bearing branch cortication, secondary fascicle development, monoecy or dioecy, presence of spermatangia on involucral filaments and monosporangia, and dimensions of trichogynes and carposporangia. Peripheral cortication has been previously used to separate species in this section, but we observed that this feature is quite widespread in the section. Presence of indeterminate gonimoblast filaments has been reported for some taxa in section Turfosa, but not such structures were seen in any of the specimen examined. Only B. keratophytum has been collected in North America, ranging from southwestern Greenland (64° N) to Louisiana (30° N). [ABSTRACT FROM AUTHOR]

Thirty-nine populations of Batrachospermum section Virescentia from North America were compared to eight Ope specimens and two historically important specimens using multivariate morphometrics and image analysis. From this analysis, two species ore recognized: B. heiminthosum Bory de Saint-Vincent (syn. B. bruziense Sirodot, B. graibussoniense Sirodot, B. sirodotii Skuja ex Flint, B. testale Sirodot, B. virgatum Sirodot nom. illeg., and B. viride Sirodot) and B. elegans Sirodot (syn. B. coerulescens Sirodot nom. illeg.). In B. helminthosum trichogynes are cylindrical to slightly club-shaped with few to no protuberances, whereas in B. elegans half to all of the trichogynes have one to three basal knobs or branches. None of the qualitative features previously used to separate species in this section were found to be of taxonomic value due to their universal presence; quantitative characteristics were highly variable and overlapped among specimens examined. Emended descriptions of both species are provided. Batrachospermum elegans was collected in northeastern US.A. and central Costa Rica, whereas B. helminthosum ranged from Nova Scotia to Louisiana and was collected in central Mexico, Costa Rica, and northwestern U.S.A. Batrachospermum julianum Arcangeli and B. transtaganum Reis, previously classified in section Virescentia, were observed to have twisted carpogonial branches and, therefore, should be placed in section Contorta. Sections Setacea and Virescentia of Batrachospermum differ in whorl size, ratio of carposporophyte height to whorl diameter, and trichogyne stalking, hence, we continue to recognize them as being distinct taxonomic entities as originally described. [ABSTRACT FROM AUTHOR]

Six populations of Batrachospermum section Setacea from North America were compared to eight type specimens using multivariate morphometrics and image analysis. From this analysis, four species in this section were distinguished worldwide: B. attrum (Hudson) Harvey [syn.B. gallaei Sirodol, B. orthostichum Skuja, B. sertularina (Bory) Bory]; B. diatyches Entwisle; B. androinvolucrum sp. nov.; and B. puiggarianum Grunow in Wittrock et Nordstedt (syn. B. angolense Welwitsch ex West et West, B. nigrescenes Welwitsch ex West et West). Two of these species were found in North America: B. attrum in California and Texas and B. androinvolucrum in British Columbia, Washington State, and Alabama. The new species, B. androinvolucrum, is distinguished by having spermatangia restricted to one-celled involucral bracts of the corpogonial branch [ABSTRACT FROM AUTHOR]

Multivariate morphometrics and image analysis were used to determine the number of well-delineated infrageneric taxa 0fSirodotia in North America. Three groupings were distinguished from 25 populations examined from Newfoundland and Quebec in the north to central Mexico in the south. These groupings were statistically related to 10 type specimens, and the following species were recognized: Sirodotia huillensis (Welwitsch ex W. et G. 3. West) Skuja (syn. S. ateleia Skuja), S. suecica Kylin (syn. S. acuminata Skuja ex Flint and S. fennica Skuja), and S. tenuilssima (Collins) Skuja ex Flint. These speies are differentiated on the basis of whorl shape and appressed; S. huillensis and S. tenuissima, truncated apex and separated), the density of spermatangia (S. huillensis, dense clusters; S. suecica and S. tenuissima, sparsely aggregated), and the mode of germination of the gonimoblast initial (S. suecica and S. tenuissima, from the nonprotuberant side of the fertilized carpogonium; S. huillensis from the protuberant side). Sirodotia huillensis was found only in the desert-chaparral, whereas S. succica and S. tenuissima occurred from southtemperate to boreal regions in cool (temperature 8-18°C), low ion (specific conductance 10-99 μ°cm[SUP-1], and mildly acidic to neutral (pH 5.7-7.3) waters. [ABSTRACT FROM AUTHOR]

Twenty-five freshwater populations of Ceramiales were collected in North America, 24 of which were from the tropical rainforest region of Central America and the Caribbean. The streams tended to be moderate in mean current velocity (&Xbar; = 23.3 cm·s[sup-1]) and maximum width (X = 6.3 m) but high in temperature (&Xbar;= 23.1°C), pH (&Xbar; 7.9), and specific conductance (&Xbar; = 320 μS·cm[sup-1] Three Bostrychia species were restricted to the Caribbean islands: B. moritziana (Sonder ex Kütz) J. Ag. (syn. B. cornigera Mont. and B. radicans f. moniliforme Post). with ecorticate indeterminate axes. monosiphonous ultimate branches, and cladohaptera; B. radicans (Mont.) Mont. (syn. B. leprieurii Mont. and B. rivularis Harv.), with ecorticate and polysiphonous axes throughout and cladohaptera; and B. tenella (Lamour.) J. Ag. with core, cate indeterminate axes, monosiphonous ultimate branches, and peripherohaptera. Ballia prieurii Kütz. was found in Belize and Costa Rica and u, as characterized by rebranched determinate laterals, opposite branching, and long apical cells (&Xbar; = 61 μm) and axial cells (X 43 μm) Caloglossa leprieurri (Mont.) J. Ag. was localiud in Puerto Rico while, C. ogasawaerensis Okam. Was collected only in Costa Rica. The two species were separated by site of branching (midrib vs. margin) and blade width 384 us 861 μm) Polysiphonia subtilissima Mont from Florida and Jamaica had four pericentral cells, no cortication, rhizoids arising from pericentral cells, and branches initiated at trichoblast scars. [ABSTRACT FROM AUTHOR]

Studies the distribution and systematics of the freshwater genus Tuomeya fluviatilis. Gametophyte development from a basal mass of undifferentiated cells rather than a chantrasia stage; No morphometric, environmental or geographic basis for separation of the groupings found.

In a survey of 1000 20-m long stream segments in North America from 73° N to 10° N, 259 infrageneric taxa were identified, composed of 35% Chlorophyta, 24% Cyanophyta, 21% Chrysophyta, 20% Rhodophyta, and one species of Phaeophyta. The most common morphological forms were mats (42%), gelatinous colonies (23%), and gelatinous filaments (13%); the majority of taxa were vegetative (78%). The frequency of reproductive states varied among the biomes examined, with the highest values observed as follows: vegetative (85%) in the tundra, sexual (35%) in the deciduous forest, and asexual (21%) in the tropical rainforest. In terms of total species, the tundra had the lowest number (54), the boreal forest had the greatest number (100), and other well-sampled biomes had 84 to 87. The Chlorophyta had the greatest species numbers in all biomes, and the relative contribution of this division did not vary significantly throughout the continent. With regard to similarity of species composition, the two closest associations were the boreal forest with the western coniferous forest and the eastern hemlock-hardwood forest with the deciduous forest. Species numbers per stream segment ranged from 0 to 11 (&Xsline; = 3.1), cover ranged from 0 to 100% (&Xsline; = 15%), and there was no significant difference in these values among the biomes. The cyanophyte Phormedium retzii (C. Ag.) Gom. was the most widespread species (in 172 segments and all biomes). The majority of species were found in moderate current velocities (&Xsline; = 40 cm · s[SUP-1]), neutral to slightly alkaline pH (&Xsline; = 7.5), and moderately low ion waters (&Xsline; = 261 μS · cm[SUP-1]). On both tropical and Arctic islands, there was no significant increase in total species or species numbers per stream segment with increasing surface area. [ABSTRACT FROM AUTHOR]

Multivariate morphometrics and image analysis were used to determient he number of well-distinguished infrageneric taxa in the section Contorta of the freshwater red algal genus Batrachospermum in North America. Five groupings were distinguished from 29 populations examined from New Mexico to costa Rica. These entities were statistically related to 12 type specimens reported from or similar to North American populations. The following taxa were recognized: B. ambiguum Montagne (syn. B. bicudoi Necchi and B. basilare Fling et Skuja) B. globosporum Israelson (syn. B. cipoense Kumano et Necchi and B. Jolyi Necchi), B. intortum Jao, B. louisianae Skuja and B. Procarpum Skuja var. americanum var. nov. The new variety differs from the nominate variety in having significantly larger whorls and smaller carpogonia. Batrachospermum ambiguum, B. louisianae, and B. procarpum var. americanum occur in low ion waters (10-187 μS·cm[SUP-1]), whereas B. intortum and B. globosporum are found in h igh ion waters (260-1760 μS·cm[SUP-1]). Detailed descriptions and a key to the five taxa are given. [ABSTRACT FROM AUTHOR]

Polysiphonia subtilissima Mont. is reported for the first time from a freshwater environment. The presence of four pericentral cells, subdichotomous branching, apical trichoblasts and rhizoids arising from pericentral cells combined with a lack of cortication and reproductive cells is consistent with marine populations of this species. The range of filament length is 1.4-4.7 cm. Branch diameters are 38-76 μm and pericentral cell lengths are 58-125 μm. Batrachospermum heterocorticum sp. Nov. is distinguished primarily by a developmental change in cortical filaments from typical cylindrical cells (5.0-7.9 μm diam) in initial stages to enlarged, elliptical cells (12.9-24.1 μm diam) in mature axes. Another unique feature of this species is carpogonia with cylindrical, pedicellate trichogynes on straight carpogonial branches in mid to outer portions of lateral whorls. Other characteristics of B. heterocorticum include the following: olive-green color, 2-6 cm length, dichotomous to trichotomous fascicles in 4-7 tiers, 385-647 μm whorl diameters, 109-198 μm carpospore diameters and relatively small "chantransia" filaments. [ABSTRACT FROM AUTHOR]

Examines the distribution and systematics of Chroodactylon and Kyliniella algae from streams in North America. Variation in the cell dimension within the populations and type specimens; Similarity in the morphometry of the population;Arrangement of pseudofilaments found in the algae.

The carpogonial branches of Batrachospermum involutum to section Batrachospermum, are similar in ultrastructure to nearby fascicles, having uninucleate cells with abundant starch granules and several peripheral, well-developed chloroplasts (up to 10 μlong). In contrast, the short carpogonial branch cells of Batrachospermum helminthosum (section Vires- cent/a) have no visible starch and chloroplasts are reduced in size (up to 2 p.m long) with few thylakoids. The breakdown of cross walls among cells of the carpogonial branch's also common in B. helminthosum but does not occur in B. involutum. As a result of cross wall breakdown in the former species, 2-7 nuclei can occur in a continuous cytoplasm. Trichogynes in both species contain scattered mitochondria. vesicles/small vacuoles, osmiophilic globules, endoplasmic reticulum (ER) and small chloroplasts. a structures also occur in the trichogyne in B. invofutum. The carpogonial base was fully observed only in B. involutum and it contains a prominent nucleus, ER, chloroplasts and a pit plug connecting it to the subtending carpogonial branch cell. Partial observations of carpogonial branches and carpogonia were made on four other members of the family Batrachospermaceae. [ABSTRACT FROM AUTHOR]

Vegetative and reproductive morphology and ultra-structure were examined for the three genera of the freshwater red algal family Lemaneaceae: Lemanea (two species, seven populations), Paralemanea (two species, three populations) and Psilosiphon (one species, one population). Psilosiphon is readily distinguished from the other two genera in having an outer cortex composed of well-defined filaments interconnected with a dense medulla (both cell types being little vacuolated), spores cleaving off obliquely, putative spermatangia scattered on the thallus sur- face and reproduction by adventitious filaments. Based on the distinctness of this genus (and corroborated by molecular phylogenies in preparation), a new family is described, the Psilosiphonaceae. Lemanea and Paralemanea appear to be closely related, with an outer cortex that has cells of increasing size and vacuolation from the periphery to the interior and not in obvious rows, a central lumen that contains few ray cells but no medullary filaments, sexual reproduction with spermatangia in distinct clusters, and carpospores in chains, some of which can germinate in the thallus lumen. Lernanea and Paralemanea have distinguishing characteristics that the other genus does not: for Lemanea, hair cells, ray cells abutting the outer cortex and spermatangia in patches; for Paralemanea, no hair cells or ray cells oppressed to the outer cortex, inner cortical filaments surrounding the central axis and spermatangia in rings. [ABSTRACT FROM AUTHOR]

The vegetative morphology and reproduction of the freshwater rhodophyte Nothocladus Iindaueri Slwja 1= Bat rachospermum lindaucri (Skuja) Necchi et Entwisle] were examined by light and electron microscopy. It was confirmed that this alga has a typical batrachospermalean pit plug with two cap layers, the outer one of which is domed. During elongation of hair cells, the primary wall is broken, forming a basal collar. Hair cells have a single nucleus and abundant Golgi bodies, endoplasmic reticula (ER) and vesicles. Dividing apical cells of the fascicles have a nucleus with an adjacent zone of exclusion, the latter containing a single polar ring. Branched trichogynes and fertilized carpogonia are shown for the first time in this species. Carpogonlal branch and invotucral cells contain a prominent axial nucleus, proplastids, ER and vesicles. The pit plugs disintegrate among these cells leaving open pit connections. Carpogonia have plentiful mitochondria and yes- ides. The wall at the trichogyne apex is thickened and densely stained. The carposporophyte centre consists of a mass of fusion cells with open pit connections, and indeterminate gonimoblast filaments arise from this mass. The combination of a symmetrical carpogonial base, a carposporophyte centre consisting of a mass of fusion cells, and exclusively indeterminate gonimoblast filaments appears to be unique among the members of the Batrachospermaceae. The specimen of N. Iindaueri contains epiphytic filaments of Audoulnella meiospora producing both spermatangia and monosporangia. Spermatium formation in N. Iindaueri remains unknown. [ABSTRACT FROM AUTHOR]

Freshwater red algae can be categorized into several morphological groups that contend with flow in different ways. Crust and tufts occur within the boundary layer and thereby may avoid mechanical stress caused by flow. The more tolerant semi-erect forms can be divided into mucilaginous and non-mucilaginous filaments as well as tissue-like thalli. Twelve taxa from these groups occur at a wide range of current velocities (&Xsline; = 24-58 cm · s[SUP-1]). There is a significant increase in strength of these forms in a gradient from tufts (&Xsline; = 12 ± 7 kN · m[SUP-2]) to mucilaginous filaments (&Xsline; = 530 ± 160 kN · m[SUP-2]) to nonmucilaginous filaments and tissues (&Xsline; = 1400 ± 400 kN · m[SUP-2]). In terms of breaking extension, no consitent trend is observed among the different morphologies; the range is 11.3-29.2% beyond the original length. Sirodotia suecica Kylin produces the least increase in dragforce with increasing flow and thus the lowest E value (-1.27) whereas the large mucilaginous species Batrachopermum boryanum Sirod. And B. virgatum (Kütz.) Sirod. Show the highest drag forces and E values (-0.45 to -0.33). Almost a ten-fold range in estimated current velocities is required to break apart the freshwater red algae tested. Predicted velocities at which the morphological groups break are as follows: tufts 80 ± 30 cm · s[SUP-1]; mucilaginous filaments, 160 ± 90 cm· s[SUP-1] and tissue, 580 ± 150 cm · s[SUP-1]. Implications regarding evolution of freshwater Rhodophyla are discussed. [ABSTRACT FROM AUTHOR]

A spring-fed, headwater stream in central Rhode Island was examined during the period from June to October, 1979 to 1982. In the first two summers, a dense riparian canopy reduced the light penetration at the stream surface to a range of 5 to 18% of incident radiation. The lotic macroalgal community during this period was limited to 1 to 4 species covering A spring-fed, headwater stream in central Rhode Island was examined during the period from June to October, 1979 to 1982. In the first two summers, a dense riparian canopy reduced the light penetration at the stream surface to a range of 5 to 18% of incident radiation. The lotic macroalgal community during this period was limited to 1 to 4 species covering <1 to 35% of the stream bottom. However, in June and July, 1981, the surrounding leaf canopy was removed by a massive gypsy moth larval outbreak. Light penetration to the stream during this summer increased to 73% by early July, there by resulting in a rise in water temperatures by 3.7°C. Even though there was a partial regrowth of leaves in late July and August of 1981, macroalgal cover values continued to rise to an early august peak of 80%. During the third summer, 88% of the macroalgal abundance could be attributed to illumination and water temperature. The filamentous diatom Eunotia pectinalis (O.F. Müll) Rabh. Was the predominant species in the mid summer of all four years, accounting for at least 60% of the total cover. In 1981, an important taxon was the desmid Hyalotheca dissilines (S. Smith) Bre´b., a species which was not seen in other years. A less severe gypsy moth defoliation occurred in 1982 but did not produce significant differences in light, temperature or macroalgal cover from 1979 and 1980. [ABSTRACT FROM AUTHOR]

Focuses on the distribution, seasonality and reproductive phenology of Bangia atropurpurea in Rhode Island. Bangia populations in winter; Upper intertidal populations from September to May; Maximum diameter of asexual and carpogonial filaments; Correlation of monosporogenesis to temperature; Relationship of gametogenesis to photoperiod.

The diatom Eunotia pectinalis (O. F. Müll.) Rabh. exhibited considerable morphological variability in samples collected over a 13-month period from a software Rhode Island stream. All observed morphotypes were classified into three main complexes based upon their valve configuration. These grouping were confirmed by discriminant analysis using quantitative value characteristics and were named in accordance with their associated varieties: minor (Kü]tz.) Rabh., pectinalis and ventricosa Grun. Clonal cultures were subjected to a defined series of temperatures, agitation rates and light intensities in order to assess inherent morphological variability. Similar trends were evident for all complexes. Over time, valve length decreased, valve breadth enlarged, and striae number per 10 μm at valve center and apex increased. Morphological plasticity was evident in culture and appeared to be more a function of the clone genotype than the environmental conditions to which it was subjected. One clone originally identified as E. pectinalis var. minor assumed certain morphological features of E. vanheurckii Patr, after four months in culture. [ABSTRACT FROM AUTHOR]

Suspended and benthic algal communities from a mildly acidic, third-order Rhode Island stream were examined to determine the seasonal distribution, abundance and diversity of the lotic desmids. Within a one-year sampling period, 148 species and 202 subspecific taxa of desmids were identified, representing 23 genera. Species of Cosmarium and Closterium accounted for approximately 70% of the desmids present, and were the most diverse and abundant taxa during all seasons except spring, when Hyalotheca dissiliens was the dominant desmid species. Average abundance and species richness generally were greatest during summer for both suspended and benthic desmids. Most desmids occurred in benthic habitats, and were randomly distributed among substrata. Average seasonal abundance was 7.4 × 10[SUP4] cells˙g[SUP-1] dry wt substratum, among 13 types of substrata. Highest desmid abundance was measured among substrata with intricate morphologies, such as Fontinalis spp., which was associated with 1.2 × 10[SUP6] desmid cells˙g[SUP-1] dry wt substratum, or 1.7 × 10[SUP3] cells˙cm[SUP-2] substratum. Cell division was observed for 70 desmid taxa, and average seasonal reproduction (based on cell numbers) among all substrata ranged from 4% in winter to 20% during summer. In addition, sexually produced zygospores were found occasionally for H. dissiliens. Desmids were distributed among most substrata examined in this stream, with abundance comparable to reported estimates from softwater lakes and acid bogs. In contrast to established dogma, lotic dismids are not incidental drift organisms, but rather comprise a viable and persistent component of the stream periphyton. [ABSTRACT FROM AUTHOR]

Studies the morphometry of freshwater red algae Batrachospermum (B) populations in New England. Size ranges of the algae; Morphological variability of the species; Distinction of the population from B. boryanum and B. ectocarpum.

Examines epiphytes of Cladophora along the north or east shores of the upper Saint Lawrence Seaway and GFreat Lakes. Distribution and abundance; Range; Dominant epiphytes; Tolerance to a wide range of salinities.

In a survey of the distribution of Bangia atropurpurea (Roth) Ag. Along the north and east shorelines of the Laurentian Great Lakes, it was observed that this species was concentrated in the lower lakes. Asexual reproduction by monospore formation was the only form of reproduction in these populations. First generation germlings derived from these spores grew in a wide range of salinities from 1 to 26%, but the rate was inversely proportional to salinity. In addition, acclimation of parent plants to fresh-water or marine media prior to sporulation affected growth rates of first generation germlings placed into a series of salinities. By the second and third generation, germlings with a lineage of seawater showed a preference for the higher salinities, 19 and 26%. Plants collected in Lake Ontario exhibited no decline in photosynthetic rate as salinity was raised by 13% for 15 min. At 26% the rate was reduced by half and thylakoids were disrupted in the region of the pyreniod. On the other hand, third generation plants with a history of seawater attained maximum photosynthetic rates at 26% and contained a normal thylakoid organization. Three chromosomes were observed in these plants, which agrees with some of the previous findings for marine Bangia. Origins and taxonomic status of Bangia growing in the Great Lakes are discussed in light of these findings. [ABSTRACT FROM AUTHOR]

The population dynamics and the sequences of statospore development and germination of Dinobryon divergens from a shallow subarctic lake were examined. D. divergens showed a sharp increase in the vegetative cell population between June 19 and July 3, 1973, followed by a rapid formation of statospores from June 26 to July 3. Shortly after spore production, this species decreases sharply to an insignificant level in the phytoplankton. Statospore formation was initiated by migration of the monad cell to the lorica mouth and proceeded by rounding up of the cytoplasm. There was then an unequal cleavage, silica wall formation around the larger portion of the cytoplasm including the nucleus and disintegration of the extracystic cytoplasm after development of he plug. The statospore was uninucleate throughout its development, and it was concluded that spore formation occurred asexually. Germination of statospores was observed in periphyton samples at depths of 20 and 80 cm on July 20-21, 1973 and in the sediments earlier the following year. During germination a cellulose chamber was produced from the pore of the statospore, followed by cleavage of the cytoplasm within the spore and migration of approximately 4 daughter protoplasts into the cellulose chamber from which they eventually escaped. The present study proposes that chrysophycean statospores arising asexually and endogenously should be recognized as separate entities from those formed isogamously and autogamously but not necessarily endogenously. The latter statospores resulting from the sexual process have been given the term zygospore. [ABSTRACT FROM AUTHOR]

Bracteacoccus minor grows on glucose both in the dark and in the light. However, the growth rates at 50 ft-c or higher in the presence of glucose are considerably lower than those in inorganic media at the same intensities. The lowered growth rates in the presence of glucose appear to be related to changes in metabolism toward increased production of storage carbohydrates. Glucose shortens the length of the lag phase at high light intensities and increases the length of the exponential phase at all light intensities, resulting in very high cell yields compared to cultures grown in inorganic media. B. minor has 2 transport systems for glucose: (1) a high affinity system, K[SUBs] = 1 × 10[SUP-5] M, which is formed in the dark in the absence of external glucose; and (2) a low affinity system, K[SUBs] = 5 × 10[SUP-4] M, which appears to be constitutive. At high concentrations of glucose there is also significant free diffusion of glucose into the cells. The glucose analog, 3-O-methyl glucose, is also taken up by the inducible system, but at a lower rate than glucose. It is cumulated about 2000 times in a 20-min incubation period, indicating active transport. Cycloheximide inactivates the high affinity system to the same extent as high light intensities, and also preincubation. The possession of a light-regulated high-affinity transport system as well as a constitutive low-affinity system for glucose is probably of competitive advantage to this alga in the soil environment. [ABSTRACT FROM AUTHOR]

Reports on the use of the sequence data from the large subunit of ribulose-1,5-biphosphate carboxylase/oxygenase gene and 18S ribosomal DNA of taxa in the freshwater order Batrachospermales to construct phylogenetic hypotheses. Generation of trees from each gene as well as a combined data set which were largely congruent; Consistent occurrence of Rhododraparnaldia on an early branch within the Acrochaetiales-Palmariales.

Cellulose acetate of the hot water soluble polysaccharide extracts from whole filaments, as well as base., mid and tip segments, of marine asexual and sexual Bangia atropurpurea (Roth) C. Ag. yielded distinctive patterns which demonstrated that changes occur in the outer cell walls during sexual reproduction. Heterogeneity of the sulfated polysaccharide components isolated from outer cell walls was shown to be specifically related to sexual reproduction. Two components (Bands I and II) were detected in extracts from tips of sexual filaments, while only one (Band I) was present in the vegetative segments of all filaments and in asexual reproductive regions. The faster running component (Band II) was detected during the later stages of sexual development, prior to maturation. [ABSTRACT FROM AUTHOR]

Presents comparative studies on the cell walls of sexual and asexual Bangia atropurpurea. Histochemical study of the nature and distribution of acidic and neutral cell wall polysaccharides; Detection of neutral polysaccharides in the outer coating; Presence of acidic polysaccharides in the outer wall material; Change in the nature of the acidic component during sexual reproduction.

Chromosome number and morphology as well as reproductive seasonality were examined in Bangia populations collected from 88 sites along the British Columbia coasts. Sexual filaments were recorded at 35 sites and asexual filaments at 58. Four different types of Bangia were determined. These were characterized by reproductive state and chromosome number, as well as by their seasonality and range of distribution. A summer-fall three-chromosome sexual type occurred from approximately 50° N northward and a winter-spring four-chromosome sexual type had a northerly limit of approximately 54°N. extending to the southernmost areas of British Columbia. Two asexual types occurred, exhibiting little seasonality, six-chromosome populations at three southerly sites only. Karyograms were prepared for the four chromosomal types, assigning tentative centromere locations. Somatic chromosome pairing was reported for the first time in the Rhodophyta. [ABSTRACT FROM AUTHOR]

The article focuses on applications of image analysis and multivariate morphometrics for algal systematica. The phenotypic plasticity exhibited by many algal taxa frequently results in classification problems when traditional methods of morphological comparison are used alone. Some investigators have applied detailed morphometric procedures to determine the range of character variation due to developmental, environmental or physiological phenomena.

The article discusses various reports published within the issue, including one on endosymbiosis and another on chromalveolates.

Diversity of the filamentous green algae in the genus Spirogyra (Zygnematophyceae) was investigated from more than 1,200 stream samples from California. We identified 12 species of Spirogyra not previously known for California ( CA), including two species new to science, Spirogyra californica sp. nov. and Spirogyra juliana sp. nov. Environmental preferences of the Californian species are discussed in the light of their restricted distribution to stream habitats with contrasting nutrient levels. We also investigated the systematic relationships of Spirogyra species from several continents using the chloroplast-encoded genes ribulose-1,5-bisphosphate carboxylase/hydrogenase large subunit ( rbcL) and the beta subunit of the ATP synthase ( atpB). Californian species were positioned in most major clades of Spirogyra. The phylogeny of Spirogyra and its taxonomic implications are discussed, such as the benefits of combining structural and molecular data for more accurate and consistent species identification. Considerable infraspecific genetic variation of globally distributed Spirogyra species was observed across continental scales. This finding suggests that structurally similar species from distant regions may be genetically dissimilar and that Spirogyra may contain a large number of cryptic species. Correlating the morphological and genetic variation within the genus will be a major challenge for future researchers. [ABSTRACT FROM AUTHOR]

Representatives of the freshwater red algal family Thoreaceae were studied to resolve their taxonomic and phylogenetic status. Three specimens of Nemalionopsis and five collections of Thorea were examined for pit plug ultrastructure and analyzed for the sequences of the genes coding for the large subunit of RUBISCO (rbc L) and the small subunit of rRNA (18S rRNA). The phylogenetic trees generated from the two genes, and a combined tree all showed the Thoreaceae to be contained in a well-supported monophyletic clade that is separate from the other two families currently classified in the Batrachospermales, the Batrachospermaceae and the Lemaneaceae. In addition, secondary structure elements of the 18S rRNA gene were observed at positions 650 and 1145 (Escherichia coli numbering system) that are not present in other members of the Rhodophyta. The pit plugs of the gametophytic and chantransia stages of the Thoreaceae contain two cap layers, the outer one of which is typically plate-like, though occasionally inflated ones have been seen. No pit plug cap membrane has been observed. These findings indicate the Thoreaceae has been misclassified in the Batrachospermales and should be placed in its own order, the Thoreales. This order is characterized by having freshwater representatives with multiaxial gametophytes, a uniaxial chantransia stage, and pit plugs with two cap layers, the outer one of which is usually plate-like. [ABSTRACT FROM AUTHOR]