Batrachospermum Gelatinosum Research Articles

Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) I: Frequent intragametophytic selfing in a monoicous, haploid-diploid species.

Life cycles with a prolonged haploid phase are thought to be correlated with greater rates of selfing and asexual reproduction. In red algae, recent population genetic studies have aimed to test this prediction but have mostly focused on marine species with separate sexes. We characterized the reproductive system of the obligately monoicous (i.e., hermaphroditic) freshwater red alga Batrachospermum gelatinosum and predicted that we would find genetic signatures of uniparental reproduction because of its haploid-diploid life cycle. We sampled 18 sites and genotyped 311 gametophytes with 10 polymorphic microsatellite loci to describe the reproductive system. Genotypic richness was low (<0.5) and pareto β values (describing clonal membership) were <0.7 for most sites. In taxa with separate sexes, these patterns are typically indicative of asexual reproduction. However, the genetic consequences of selfing in monoicous gametophytes are indistinguishable from those caused by asexual processes. Since we sampled gametophytes and have not yet genotyped the chantransia (i.e., the diploid phase), we interpretedlow diversity as a signature of intragametophytic selfing. Additionally, to understand the factors that drive selfing, we tested latitude and several other environmental variables, but none was significantly correlated with the genetic variation we observed. Nevertheless, future studies should genotype the chantransia to measure observed heterozygosity among other summary statistics to disentangle the effects of selfing versus asexual reproduction. Together, these data, coupled with further characterization of abiotic factors that influence population genetic patterns, will allow us to test potential drivers of reproductive system evolution.

Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) II: Phylogeographic analyses reveal spatial genetic structure among and within five major drainage basins in eastern North America.

The freshwater red alga Batrachospermum gelatinosum has a well-documented distribution spanning historically glaciated and unglaciated eastern North America. This alga has no known desiccation-resistant propagule; thus, long-distance dispersal events are likely rare. We predicted strong genetic structure among drainage basins and admixture among sites within basins. We predicted greater genetic diversity at lower latitude sites because they likely serve as refugia and the origin of northward, post-Pleistocene range expansion. We used 10 microsatellite loci to investigate genetic diversity from 311 gametophytes from 18 sites in five major drainage basins: South Atlantic Gulf, Mid-Atlantic, Ohio River, Great Lakes, and Northeast. Our data showed strong genetic partitioning among drainage basins and among sites within basins, yet no isolation by distance was detected. Genetic diversity varied widely among sites and was not strictly related to latitude as predicted. The results from B. gelatinosum provide strong support that each stream site contributes to the unique genetic variation within the species, potentially due to limited dispersal and the prevailing reproductive mode of intragametophytic selfing. Simulations of migration suggested post-Pleistocene dispersal from the Mid-Atlantic. Batrachospermum gelatinosum potentially persisted in refugia that were just south of the ice margins rather than in the southernmost part of its range. Research of other taxa with similar ranges could determine whether these results are generally applicable for freshwater red algae. Nevertheless, these results from B. gelatinosum add to the growing literature focused on the patterns and genetic consequences of post-Pleistocene range expansion by eastern North American biota.

Fine-tuning RNA extraction protocols for polysaccharide-rich freshwater red algae (Rhodophyta).

Freshwater red algae are important primary producers, widely distributed, contributing significantly to nutrient cycling in aquatic ecosystems. Recent studies have focused on identifying the effect of different environmental conditions such as light on the gene expression in photosynthesis pathways. However, obtaining the necessary RNA quantity and quality for sequencing from these algae has been challenging. Although RNA extractions have been optimized for model organisms, RNA extraction for non-model organisms, such as gelatinous (polysaccharide-rich) red algae, requires considerable troubleshooting. The common freshwater red alga, Batrachospermum gelatinosum , was used to test protocols. The extraction efficiency of various sample disruption methods in combination with seven RNA extraction kits was compared. Using a 2-minute disruption procedure with a modification of TRIzol ™ Plus RNA Purification Kit (PureLink ™ RNA Mini Kit + Trizol ™ ) protocol resulted in significantly higher RIN scores (p < 0.05) and high RNA concentration, compared to other methods. The fine-tuned protocol yielded quality RNA (RIN>7) in high concentrations for subsequent sequencing.

Diversity of Batrachospermales (Rhodophyta) in the Iberian Peninsula

Fifty-four streams of the Iberian Peninsula were investigated to document the species richness and phylogeny of Batrachospermum and morphologically similar genera, determine phylogenetic affinities of taxa and infer biogeographic trends. Species were identified using morphology and DNA sequence data for the rbcL gene as follows: Batrachospermum gelatinosum, B. pozoazulense, Paludicola keratophyta, Sheathia arcuata, S. boryana, S. confusa, Torularia atra, Virescentia helminthosa, V. vogesiaca, and Volatus carrionii. Batrachospermum gelatinosum and S. boryana were most frequent (sampled from 16 and 11 streams, respectively). Torularia atra and V. vogesiaca were each collected in a single stream, whereas the other five taxa were present in three to six streams. Virescentia vogesiaca is well known from other parts of Europe but had previously not been reported from the Iberian Peninsula. Biogeographic trends based on DNA sequence data show a flora with most species being well represented in parts of Europe, two taxa (B. gelatinosum and V. carrionii) that are shared between Europe and North America, one between Europe and South America (Paludicola keratophyta) and one cosmopolitan species (T. atra). Previous studies reported twelve taxa in the region using current taxonomy. This study has confirmed seven of these taxa with sequence data and morphology.

Batrachospermales (Rhodophyta) of China: a catalogue and bibliography

A catalogue and bibliography of Batrachospermales (Rhodophyta) in China is presented. There are 33 species belonged to 10 genera and 2 families. Species distribution among the 10 gen- era are as follows: Batrachospermum, 6; Kumanoa, 10; Montagnia, 1; Nothocladus, 1; Sheathia, 3; Sirodotia, 4; Torularia, 1; Virescentia, 1; Lemanea, 4; and Paralemanea, 2. According to geo- graphical distribution, the members of Batrachospermales in China are composed of 3 types: cos- mopolitan (distributed on at least 5 continents or 10 countries of the world), 6 taxa; regionally dis- tributed (distributed in no more than 4 continents or 10 countries), 15 taxa; and endemic to China (collected, described and reported only from China), 12 taxa. Most species were distributed in East and Southwest China, up to or more than 20 species. Eight species were recorded in North and Central China, respectively. Only 1 or 2 species were found in Northeast and South China, respec- tively. However, no one has been found in the northwest China so far. Thirteen species of Batra- chospermales in China have been confirmed by morphological characteristics combining with mo- lecular data. But unfortunately, the other species are unable to obtain molecular data because fresh collections are not available, which need to be confirmed or rejected in future studies. Kylin, H. (1912): Studien über die schwedischen Arten der Gattung Batrachospermum Roth und Sirodotia nov. gen. – Nova Acta Reg. Soc. Sci. Upsal., Series 4, 3 (3): 1–40. Li, L. C. (1939): Freshwater algae of Yunnan expedition 1935–1937. – Bull. Fan Mem. Inst. Biol., Bot. Series 9: 31–57. Li, L. C. (1940): Additions to the freshwater algae of Yunnan. – Bull. Fan Mem. Inst. Biol., Bot. Series 10: 47–67. Li, Q. &amp; Xie, S. L. (2009): Studies on intraspecific variation of Batrachospermum gelatinosum (Rhodophyta). – J. Shanx. Univ. (Nat. Sci. Ed.) 32 (S1): 113–115. Li, Q., Ji, L. &amp; Xie, S. L. (2010): Phylogenetic analysis of Batrachospemales (Florideophyceae, Rhodophyta) based on chloroplast rbc L sequences. – Acta Hydrobiol. Sin. 34 (1): 20–28. Liao, L. M. (2010): Nomenclatural notes on some Philippine species of freshwater red algae (Rhodophyta). – Phil. J. Syst. Biol. 4: 89–94. Linnaeus, C. (1753): Species Plantarum, Vol. 2. Impensis Laurentii Salvii, Holmiae. Luo, A. G., Hu, B. F. &amp; Xie, S. L. (2009): A preliminary study on the alage in Jinci Park, Shanxi Province. – J. Jinzh. Univ. 26 (3): 51–54, 85. Lyons, T. W., Reinhard, C. T. &amp; Planavsky, N. J. (2014): The rise of oxygen in Earth's early ocean and atmosphere. – Nature 506 (7488): 307–315. McNeey, J. A. (1994): Protected areas for the 21st century: working to provide benefits to society. – Biodivers. Conserv. 3 (5): 390–405. Montagne, C. (1850): Cryptogamia Guyanensis, seu plantarum cellularium in Guyana gallica annis 1835–1849 a Cl. Leprieur collectarum enumeratio universalis. – Ann. Sci. Nat., Bot., Trois. Série 14: 83–309. Nan, F. R., Feng, J. &amp; Xie, S. L. (2014a): Phylogenetic relationship of genus Kumanoa (Batrachospermales, Rhodophyta) based on chloroplast UPA genes. – Bull. Bot. Res. 34 (5): 584–591. Nan, F. R., Feng, J. &amp; Xie, S. L. (2014b): Advances on systematics of Kumanoa (Batrachospermales, Rhodophyta). – World Sci.-Tech. Res. Devel. 36 (3): 33–39. Nan, F. R., Feng, J. &amp; Xie, S. L. (2015): Phylogenetic analysis of genus Kumanoa based on chloroplast psa A and psb A genes. – Acta Hydrobiol. Sin. 39 (1): 155–163.

Survey of Freshwater Red Algae from the Batrachospermales (Rhodophyta) in South Carolina

Freshwater red algae are important components of the algal flora in streams and rivers with high water quality. The order Batrachospermales is the most species-rich portion of the red algal taxa reported throughout North America. We investigated 30 stream segments in South Carolina for the presence of freshwater red algae classified within the Batrachospermales. We collected a total of 50 specimens representing 7 genera and 9 species. We documented Batrachospermum gelatinosum, B. turfosum, Kumanoa skujana, Montagnia australis, Sheathia americana, S. heterocortica, Sirodotia suecica, Tuomeya americana, and Virescentia viride-americana. We observed M. australis and T. americana from the greatest number of streams and in multiple years from the same site. We observed V. viride-americana in 3 streams; our specimens represent the only new record for the state. We generated DNA sequence data of the rbcL gene or gleaned it from the literature for 8 of the 9 taxa identified in the study and confirmed their morphological identification. We collected stream temperature, pH, and conductivity data from sites where we collected 6 of the taxa (Batrachospermum gelatinosum, B. turfosum, M. australis, Sheathia americana, T. americana, and V. viride-americana). Our records were within previously reported ranges for these taxa, although water temperatures tended to be higher than those in previous reports. Present data for the diversity of Batrachospermales in South Carolina represent 64% of the generic/infrageneric and 20% of the species diversity known for North America. This diversity may still be an underestimation of what might be detected by future studies that target more specialized habitats; taxa that are known from neighboring states but not yet reported from South Carolina might be discovered.

Freshwater red algae in Finland

AbstractThere were only less than sixty records of freshwater red algae in Finland until the 1980s, when the author began sampling the running waters of southern and central Finland; 516 new records were made in 1984–2011. More intensive research began in 2012, with a few field teams working at first in Central Finland Province and then covering the whole country. The project continued until 2018. During these studies approximately 3400 new locations were investigated and 3641 new records of 29 taxa were made. Since 2013, 12 ecological variables have also been measured or estimated. The share of positive records from the studied locations varied from 49% to 86% (avg. 72%), being highest in Lapland (85.5%). The most frequent taxa were Batrachospermum gelatinosum (36.5%), Audouinella hermannii (14.5%), Sheathia arcuata (9.3%), Sirodotia suecica (8.4%), Audouinella chalybea (4.7%), Lemanea fluviatilis (3.8%) and Lemanea fucina (2.8%). Batrachospermum elegans, Kumanoa virgatodecaisneana and Lemanea mamillosa occurred in southwestern Finland in waters with higher conductivity, whereas Batrachospermum turfosum and Virescentia vogesiaca were typical taxa of acidic and soft water. Batrachospermum sporulans and Lemanea condensata occurred only in northern Finland. Some records did not fit the recent morphological keys and should be analysed using molecular methods.

Photosynthetic performance of two freshwater red algal species

Abstract Photosynthetic performances of two freshwater red algal populations from freshwaters of the Carpathian basin were measured in this study. Populations were collected from different habitats: Bangia atropurpurea from Lake Balaton and Batrachospermum gelatinosum from the Tapolca stream. Their photosynthesis was studied in a wide range of temperature (5–35 °C) and light intensity (0–1150 μmol m−2 s−1) in a photosynthetron. We found both species’ photosynthesis maxima at 25 °C but B. atropurpurea had significantly higher photosynthetic production. Low and medium values were calculated for the species’ photoadaptation parameters. Compensation light intensities determined in this study were similar to those obtained in previous studies. Both species utilized light efficiently; photoinhibition was detected only at two measuring temperatures for Bangia and at four measuring temperatures for Batrachospermum. P-T characteristics of the species revealed that both have temperature optima at 25 °C under high and medium light intensities but there are no such remarkable optima at low irradiance. The biomass specific respiration of both species increased with increasing temperature. We confirmed the good light utilization of these red algal species but found temperature optima higher than reported previously.

Ecology and distribution of macroscopic algae communities in streams from the Basin of Mexico

Background: Several studies of lotic ecosystems have provided important ecological information on the influence of environmental heterogeneity on macroscopic algae composition.Hypothesis: The highest species diversity will occur during the cold-dry season, correlated to low temperature and oligothrophic water, while the distribution of each species will be related to heterogeneity of habitat and its dispersal strategies.Studied species: Twenty-two species of macroscopic algae of different Phyla (Chlorophyta, Cyanobacteria, Heterokontophyta and Rhodophyta).Study site: The macroscopic algae composition was described for 35 permanent mountain streams in the Basin of Mexico from 2012 to 2015.Methods: Algae species, physico-chemical water conditions and microhabitat factors were recorded in situ at each contrasting season. The relationship between diversity and the environmental factors was statistically evaluated by Canonical Correspondence Analysis and a Spearman test. Results: Macroscopic algae recorded had biological features and environmental abilities that separated them into two groups. The first included the most frequent and abundant species: Nostoc parmelioides, Placoma regulare, Prasiola mexicana and Vaucheria bursata . The second included species restricted to certain habitats: Draparnaldia mutabilis, Tetraspora gelatinosa , Batrachospermum gelatinosum and Paralemanea mexicana . Each Phyla responds differentially to the spatial heterogeneity of the streams, but the species does not change between contrasting seasons.Conclusions: Local and spatial environmental variables explain differences in richness and distribution of species on the studied area; however, species composition does not vary widely among sampling sites. Cyanobacteria and Chlorophyta are more affected by local environmental variables, whereas Rhodophyta is more influenced by spatial variables.

The last peri-urban rivers of the Mexico Basin: establishment of potential reference conditions through the evaluation of ecological quality and biological indicators

In assessing the health of rivers, the standardization of environmental and biological information as a baseline is essential in order to determine the set of conditions that are closest to the natural state of ecosystems. This is the case especially in peri-urban rivers where anthropogenic transformations occur rapidly and constantly. The objective of this work was to determine hydromorphological, physicochemical and biological parameters in 10 mountain rivers of the Mexico Basin, in order to establish a network of potential reference conditions and to validate the regional ecological quality. The potential reference conditions in this study are defined as oligotrophic water bodies with well-oxygenated concentrations and low ion concentrations. These conditions were recorded in 4 sub-basins with high hydromorphological quality. These results were corroborated through a base assembly composed of the macroinvertebrate families Baetide, Chrironomidae, Dugesiidae, Heptageniidae, Limnephilidae, Tipulidae and the class Arachnida (Acarina). The algal community was represented by Nostoc parmelioides, Placoma regulare, Batrachospermum gelatinosum, Paralemanea mexicana, Draparnaldia mutabilis, Prasiola mexicana and Vaucheria bursata. The major disturbances were structural changes in the riverbed that affect the structure and function of rivers.

Intensive study of freshwater red algae (Rhodophyta) in Finland

Abstract: Freshwater red algae (Rhodophyta) were studied in Central Finland by examining 2224 rivers and brooks during the open water periods of the years 2012-2015 with supplementary sampling in S- and SW-Finland, the W-coast rivers and Lapland. A total of 1957 records of algae were made. Approximately 56.2% of the studied locations had 1-6 taxa. The total taxa collected were 25, with 5 taxa new to Finland. While sampling, ecological variables were recorded and measured. The most common taxa were Batrachospermum gelatinosum (37.0%), Sheathia arcuata (10.7%), Audouinella hermannii (11.2%) and Sirodotia suecica (7.0%). Lemanea spp. (9.9%) occurred in larger rivers. Most records were from July and August, but some also in winter months. From the most rare taxa, Lemanea condensata was found in Lapland rivers, Batrachospermum vogesiacum in acid, dystrophic rivers in Central Finland, B. atrum in 7 eutrophic rivers, Kumanoa globospora in 6 rivers of Central Finland, Batrachospermum elegans in 6 and K. virgatodecaisneana in 5 harder-water rivers of SW-Finland.

Phylogeography of Batrachospermum gelatinosum (Batrachospermales, Rhodophyta) shows postglacial expansion in Europe

:The freshwater red alga Batrachospermum gelatinosum inhabits streams of Europe and North America and has been collected frequently on both continents. A study of this species in North America showed evidence of a glacial refugium in the southeastern United States with little genetic variation throughout its more northern range in eastern North America. The present study was initiated to investigate its phylogeography throughout Europe and to compare these results with those obtained for North America. Specimens were collected from Belgium, Estonia, Finland, France, Great Britain, Italy, Latvia, Lithuania, Poland and Spain. Both the mitochondrial cytochrome c oxidase subunit I (COI) barcode region and the nuclear rDNA internal transcribed spacer (ITS 1 and 2) regions were analysed. Of the 70 individuals analysed, 12 COI haplotypes were uncovered. In addition, ITS variation of 67 individuals was surveyed and showed 21 haplotypes. The haplotype network of COI data showed a large number of the individuals distributed among three common haplotypes. The other nine haplotypes differed from the common ones by only one to two base pairs and were represented by only one to six individuals. The ITS network had a star appearance with a common haplotype (17 individuals) and many closely related haplotypes with few individuals per haplotype. Compared to North America, there were more COI haplotypes present in Europe (12 vs 5), and the relationship among haplotypes was more complex. The geographic distribution of haplotypes did not appear to follow a glaciation pattern; rather, the common haplotypes were widespread, suggesting a recent expansion.

Varied phenologies of Batrachospermum gelatinosum gametophytes (Batrachospermales, Rhodophyta) in two low-order streams.

The freshwater red algal species, Batrachospermum gelatinosum, is common in temperate/borea regions North America and Europe. In southeast Ohio, gametophytes of this taxon were observed to have two different phenologies; in one stream the gametophytes were present only during the spring months and in another stream they were present year-round. Therefore, the purpose of this study was to determine environmental parameters associated with occurrence, peak vegetative growth and reproduction for B. gelatinosum gametophytes in these two streams. Field sampling was conducted for 18 months with both streams being sampled every three to four weeks, when possible. Physical and chemical parameters of stream depth, current velocity, pH, conductivity and nutrients were measured each sampling date. Algal thalli were measured for changes in both vegetative and reproductive characters. In both streams, algal reproductive structures were positively correlated with stream depth (7-52 cm), but there was no correlation of vegetative characteristics with environmental variables measured. Algal cover (0-50 %) in each stream was positively correlated with stream depth (7-52 cm), current velocity (BDL-1.08 m.s-1) and day length (10.3-15.1 hrs). The site with the least canopy cover and greatest water depth had the highest algal cover and gametophytes present year-round; whereas the site with lower water depth had lower algal cover and gametophyte present only during spring and early summer. This result suggests that stream size and amount of riparian vegetation may play a role in determining phenologies observed. Contrasting phenologies have been reported for B. gelatinosum from sites that are geographically distant, but this study has found that local physical factors may produce differing phenologies in streams only a few kilometers apart.

Diversity, Ecology and Survivor of Freshwater Red Algae in Israel

From 1950s till now only seven species of Rhodophyta were recorded from continental waters of Israel. Among them, the most abundant are the species of Audouinella that inhabit fresh or brackish waters of lakes, pools and rivers. Our findings of two species of this genus inhabiting the fresh clear water Oren River, the middle reaches of the polluted Qishon River (A. pygmaea (Kutz.) Weber-van Bosse)), as well as the middle reaches of the strongly impacted Lower Jordan River (A. hermannii (Roth) Duby in De Candolle). These findings led us to conclude the latter species preferred low to moderate salinity and a high calcium concentration and is relatively resistant to organic pollution. Bangia atropurpurea (Mertens ex Roth) C. Agardh and Hildenbrandia rivularis (Liebmann) J. Agardh are the sensitive species sporadically observed in a few habitats only and preferring the slightly mineralized slow streaming carbonate waters with insignificant organic pollution. Batrachospermum gelatinosum (Linnaeus) De Candolle is only one new for Israel species that has been found in the Meshushim stream. The likewise sensitive Phragmonema sordidum Zopf is consider as a lost species because of the loss of habitat. We do not confirm finding of red algae Paralemanea catenata (Kutzing) Vis et Sheath in the Banias stream.

Contribution to the Knowledge of Red algae (Rhodophyta) of some Rivers in Central Italy

Abstract There are no specific studies on freshwater red algae from Italy, and the few existing data are reported in broader studies on algae of rivers. The aim of this paper is to contribute to the knowledge of this algal group in Italy, providing data on their distribution, morphological features and ecology. Samples of Lemanea fluviatilis, L. sudetica and Batrachospermum gelatinosum were collected from 5 stations in the Tiber River basin (Central Italy). The recorded taxa are known as typical elements of European rivers' algal flora, however they were reported in a few times in Italy. Our records, therefore, have widened their geographical distribution. Morever, the finding of L. sudetica was, for the first time, recorded with certainty in rivers of Central Italy.

Morphological and ecological characterization of Batrachospermales (Rhodophyta) in the Jarama Basin, Iberian Peninsula

Five populations of freshwater red algae were investigated between February 2008 and September 2009 in four segments of the Jarama River Basin (Tajo Basin), Iberian Peninsula, between 40-41◦ N, 3-4◦ W, at 700 to 1200 m altitude. Three species were documented (Batrachospermum gelatinosum, Lemanea fluviatilis and Paralemanea catenata) and information was collected about includes their morphology and the physical and chemical characteristics of the water. All the taxa have been reported previously, but the present work includes the first detailed morphological description of red algae in the region and their ecological preferences. The waters in these study sites are cool to temperate (5-17 ◦C), acid to circumneutral (pH 6.3-7.5) and with a low ion concentration (specific conductivity 77-270 μS cm−1). Two groups were distinguished on the basis of nutrient concentration. The first group, which included B. gelatinosum and L. fluviatilis, is found in clean water with low nutrient concentration, while the second group, which included P. catenata, occurred in nutrient-rich water. Gametophytes of L. fluviatilis and P. catenata were present in all seasons, with the highest percentage cover in autumn and winter corresponding to high current velocity and low water temperature. However, gametophytes were longest, and spermatangial sori and carposporophytes were most abundant in spring when current velocity was low and water temperature was high. The distribution of Batrachosermales from the Jarama Basin showed a strong affinity with temperate regions of central Europe and floras of other continents.

Intraspecific genetic variation of Batrachospermum gelatinosum (Batrachospermales, Rhodophyta) in eastern North America

House D.L., Vandenbroek A.M. and Vis M.L. 2010. Intraspecific genetic variation of Batrachospermum gelatinosum (Batrachospermales, Rhodophyta) in eastern North America. Phycologia 49: 501–507. DOI: 10.2216/09-104.1Batrachospermum gelatinosum is a widespread taxon of freshwater red algae in eastern North America and elsewhere in the northern hemisphere. A total of 193 individuals from 16 stream segments in eastern North America ranging from Alabama in the south to Nova Scotia in the north, as well as three individuals from Europe were collected. Genetic variation among these individuals was assessed using the cox1 barcoding region. Five haplotypes were revealed from the North American specimens with a single widespread haplotype representing most individuals. Of the other four haplotypes, three were collected exclusively in Alabama and one in Massachusetts. These five haplotypes only differed by 1–4 bp. There were two haplotypes detected in the European samples, which differed from the North American ones by 7–10 bp. This study substantiates previous research using the internal transcribed spacer region that B. gelatinosum is a genetically homogenous species that is highly plastic in its morphology. The data from this study implies a southern glacial refugium potentially in Alabama and subsequent dispersal of one haplotype to all northern areas. This pattern is similar to that seen in B. helminthosum and numerous other organisms. Currently, there are only genetic data on three freshwater red taxa, and information from other widespread Batrachospermales in eastern North America are needed to provide generalized phylogeographic patterns for this group and compare them with other aquatic organisms.

Temporal and spatial distribution of macroalgal communities of mountain streams in Valle de Bravo Basin, central Mexico

The stream macroalgal community is controlled by heterogeneous physical, chemical, and biological factors related with multiple spatial and temporal scales; however, the mechanisms that explain diversity and distribution are scarcely known. The present investigation was conducted to characterize the macroalgal community structure and spatial and temporal distribution and to recognize biogeographic affinities with mountain streams from other regions. Habitat characteristics, abundance, and diversity were investigated in four mountain streams of Valle de Bravo Basin, central Mexico, during two annual cycles. Sampling of visible benthic growths was collected in the most contrasting parts of the year. Physicochemical parameters were recorded in situ at each site and the main ions and nutriments were evaluated for every collection. Statistical analysis between dates was assessed with one-way analysis of variance (ANOVA) and Canonical Correspondence Analysis (CCA). Observed richness average was four species per site and the high abundance of Phormidium interruptum, Nostoc parmelioides, Paralemanea mexicana, Batrachospermum gelatinosum, Sirodotia suecica, Cladophora glomerata, and Prasiola mexicana correlated with cold dry season, high current velocity, and a major size substrate. Valle de Bravo streams can be viewed as a habitat subjected to moderated disturbance, mainly due to the effects of seasonal changes in rainfall contrary to torrents expected of tropical regions. The seasonal patterns of macroalgal communities in Valle de Bravo basin were typically characterized by two distinct periods essentially determined by the rainfall regime and related to temperature, and can be viewed as habitats subjected to moderate disturbance according to intermediate disturbance hypothesis. The distribution species pattern registered suggests a group of temperate species frequently found in mountain regions of the Mexican Volcanic Belt and temperate eastern region of North America and may indicate a possible biogeographic connection with the Neartic region with similar environmental requirements.

Investigation of two species complexes in Batrachospermum section Batrachospermum (Batrachospermales, Rhodophyta)

S.A. Stewart and M.L. Vis. 2007. Investigation of two species complexes in Batrachospermum section Batrachospermum (Batrachospermales, Rhodophyta). Phycologia 46:380–385. DOI: 10.2216/06-86.1Within Batrachospermum section Batrachospermum, there are two putative species complexes with members that only differ by breeding system alone or this trait with a single vegetative character. New sequence data for the rbcL gene were generated from specimens of B. anatinum, B. arcuatum, B. boryanum, B. confusum and B. heterocorticum in order to assess the phylogenetic value of heterocortication on the main axis of the thallus and further explore the taxonomic utility of breeding system. The presence of heterocortication in B. involutum was confirmed, and this character served as a synapomorphy for a clade containing this taxon and B. anatinum, B. boryanum, B. confusum and B. heterocorticum. The rbcL sequences were identical for the two monoecious species: B. anatinum with spermatangia confined to the tips of vegetative branches and B. confusum with spermatangia on involucral filaments of the carpogonial branches as well as the vegetative ones. It is argued that knowledge of spermatangia placement is of ecological importance, and B. anatinum f. confusum is proposed rather than simply placing the two entities in synonymy. There was no clear support for or against the use of breeding system as a taxonomic character, with pairs of morphologically similar species differing primarily by breeding system grouped together. Batrachospermum gelatinosum and B. gelatinosum f. spermatoinvolucrum from North America were not part of the clade formed by the other taxa studied. In fact, they were nested distantly in a clade containing other genera in the Batrachospermaceae. Among the taxa with heterocortication, B. anatinum, B. boryanum, B. heterocorticum and B. involutum, each was at least 1.4% different in its rbcL sequence from its closest neighbor. The present research provides more evidence that section Batrachospermum will need to be split with the potential of resurrecting section Helminthoidea and that the generic classification needs revision.

The distribution of Rhodophyta in streams of Central Mexico

The distribution of species of Rhodophyta was investigated in 424 stream segments, sampled from 1981–1999 in three river basins from central Mexico. Red algae occurred in 12% of the stream segments sampled, a low frequency compared to major surveys in other parts of the world (18–65%). Sixteen species of freshwater red algae were found, of which the most widespread were Compsopogon coeruleus (24 sites) and Hildenbrandia angolensis (16 sites). Two groups of species were clearly distinguished on the basis of environmental characteristics. The first group, which included Batrachospermum gelatinosum, Paralemanea annulata, P. mexicana and Sirodotia suecica, is found in temperate climates, high altitudes (>1700 m), and cold or temperate waters (12–18°C) that are slightly acidic (pH 5.5–6.5) and of low specific conductivity (77–86 μS . cm–1). The second group, including Chroodactylon ornatum, Compsopogon coeruleus, Hildenbrandia angolensis, Audouinella eugenea, A. huastecana, A. meiospora, Batrachospermum globosporum, Sirodotia huillensis and Thorea hispida, is of subtropical to tropical climates, low altitudes ( 21°C) that are neutral to slightly alkaline (pH 7.0–8.6) and of high specific conductivity (160–1990 μS.cm–1). Half of the species found in this study were exclusively of calcareous sites from within a highly homogeneous limestone region (56% Ca). The rest of the sites with rhodophytes were found in sub-basins with andesitic-basaltic or calcareous substrates, and in temperate to semidesertic climates that provoke dramatic changes in the water level of the river or even the complete absence of permanent rivers. A high percentage of the currents contained an influx of organic material in which populations of Compsopogon coeruleus, described as tolerant of these conditions, could be found. The sub-basins that were most similar and had the least diversity corresponded to high mountain regions of Central Mexico (HP and HB). The overall species composition for streams and rivers of Central Mexico revealed high similarities with other tropical regions and had few species in common with freshwater red algal floras of other continents.