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The freshwater red algal genus Sheathia contains species with heterocortication (both bulbous and cylindrical cells covering the main axis) and homocortication (only cylindrical cells). When the genus was proposed, the species with heterocortication were revised, but all specimens with homocortication were assigned to Sheathia arcuata with the caveat that it may represent a species complex. Recent studies have described new species with homocortication and S. arcuata has been rendered paraphyletic. In the current study, new sequences of the rbcL and 5′ region of the cytochrome c oxidase subunit I markers were combined with previously published data to construct a robust phylogeny and circumscribe new species. Four new species, S. abscondita, S. californica, S. plantuloides, and S. transpacifica are proposed. Examination of morphological characters among homocorticate species show no diagnostic characters to distinguish among species, whereas S. plantuloides is only known from sporophytes (chantransia) so it lacks the typical morphological characters derived from the gametophytes for comparison. Although DNA sequence data would be needed to make a positive species identification, geography could be employed to narrow the identification to one or two species. The genus is geographically widespread having been recorded from oceanic islands and five continents, whereas the individual species typically occur on a single continent. With this study, the number of species recognized in Sheathia is raised to 17; seven heterocorticate and 10 homocorticate, making this genus one of the most species rich in the Batrachospermales. As well, the resulting phylogeny provides insights into the evolution of heterocortication in Sheathia. [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]

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]

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]

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]

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]