Paludicola gen. nov. and Revision of the Species Formerly in Batrachospermum Section Turfosa (Batrachospermales, Rhodophyta).

Since the first phylogenetic study of the order Batrachospermales, Batrachospermum was shown to be paraphyletic. Subsequently, sections of the genus have been methodically investigated using DNA sequences and morphology in order to propose new genera and delineate species. Batrachospermum section Turfosa is the last section with multiple species yet to be examined. New sequence data of specimens from Europe and the United States were combined with the sparse sequence data already available. Phylogenetic analyses using rbcL and COI-5P sequences showed this section to be a well-supported clade, distinct from Batrachospermum section Batrachospermum and its segregate genera. Section Turfosa is raised to the generic rank as Paludicola gen. nov. Substantial genetic variation within the genus was discovered and 12 species are recognized based on DNA sequence data as well as morphological characters and geographic distribution. The following morphological characters were applied to distinguish species: branching pattern (pseudodichotomous or irregular), whorl size (reduced or well developed), primary fascicles (curved or straight), spermatangia origin (primary or secondary fascicles), and carposporophyte arrangement (loose or dense). Previously published species were transferred to the new genus: P. turfosa, P. keratophyta, P. orthosticha, P. phangiae, and P. periploca. Seven new species are proposed as follows: P. groenbladii from Europe; P. communis, P. johnhallii, and P. leafensis from North America; and P. aquanigra, P. diamantinensis, and P. turfosiformis from Brazil. In addition, three unsequenced species in the section, P. bakarensis, P. gombakensis, and P. tapirensis, were transferred to the new genus.

Complete mitochondrial genomes of six species of the freshwater red algal order Batrachospermales (Rhodophyta).

Only two mitochondrial (mt) genomes had been reported in members of the red algal order Batrachospermales, which are confined to freshwater habitats. Additional mt genomes of six representative members (Batrachospermum macrosporum, Kumanoa ambigua, K. mahlacensis, Paralemanea sp., Sheathia arcuata, and Sirodotia delicatula) were sequenced aiming to gain insights on the evolution of their mt genomes from a comparative analysis with other red algal groups. Mt genomes sequenced had the following characteristics: lengths ranging between 24,864 nt and 29,785 nt, 22 to 26 protein-coding genes, G + C contents of 21.3 to 30.7%, number of tRNA of 16 to 37, non-coding DNA from 3.8% to 14.8%. Comparative analysis revealed that mt genomes in Batrachospermales are highly conserved in terms of genome size and gene content and synteny. Phylogenetic analyses based on COI nucleotide data revealed high bootstrap support only for the genera usually recovered in the phylogenetic analyses but no support for supra-generic groups. The insertion of a group II intron carrying an ORF coding for the corresponding intron maturase interrupting the COI gene was observed in Paralamenea sp. and accounted for its larger genome in comparison to the other Batrachospermales mt genomes.

Organization of plastid genomes in the freshwater red algal order Batrachospermales (Rhodophyta).

Little is known about genome organization in members of the order Batrachospermales, and the infra-ordinal relationship remains unresolved. Plastid (cp) genomes of seven members of the freshwater red algal order Batrachospermales were sequenced, with the following aims: (i) to describe the characteristics of cp genomes and compare these with other red algal groups; (ii) to infer the phylogenetic relationships among these members to better understand the infra-ordinal classification. Cp genomes of Batrachospermales are large, with several cases of gene loss, they are gene-dense (high gene content for the genome size and short intergenic regions) and have highly conserved gene order. Phylogenetic analyses based on concatenated nucleotide genome data roughly supports the current taxonomic system for the order. Comparative analyses confirm data for members of the class Florideophyceae that cp genomes in Batrachospermales is highly conserved, with little variation in gene composition. However, relevant new features were revealed in our study: genome sizes in members of Batrachospermales are close to the lowest values reported for Florideophyceae; differences in cp genome size within the order are large in comparison with other orders (Ceramiales, Gelidiales, Gracilariales, Hildenbrandiales, and Nemaliales); and members of Batrachospermales have the lowest number of protein-coding genes among the Florideophyceae. In terms of gene loss, apcF, which encodes the allophycocyanin beta subunit, is absent in all sequenced taxa of Batrachospermales. We reinforce that the interordinal relationships between the freshwater orders Batrachospermales and Thoreales within the Nemaliophycidae is not well resolved due to limited taxon sampling.

MOLECULAR PHYLOGENY OF THE GENUS KUMANOA (BATRACHOSPERMALES, RHODOPHYTA)(1).

Species belonging to the newly established genus Kumanoa were sampled from locations worldwide. DNA sequence data from the rbcL gene, cox1 barcode region, and universal plastid amplicon (UPA) were collected. The new sequence data for the rbcL were combined with the extensive batrachospermalean rbcL data available in GenBank. Single gene rbcL results showed the genus Kumanoa to be a well-supported clade, and there was high statistical support for many of the terminal nodes. However, with this gene alone, there was very little support for any of the internal nodes. Analysis of the concatenated data set (rbcL, cox1, and UPA) provided higher statistical support across the tree. The taxa K. vittata and K. amazonensis formed a basal grade, and both were on relatively long branches. Three new species are proposed, K. holtonii, K. gudjewga, and K. novaecaledonensis; K. procarpa var. americana is raised to species level. In addition, the synonymy of K. capensis and K. breviarticulata is proposed, with K. capensis having precedence. Five new combinations are made, bringing the total number of accepted species in Kumanoa to 31. The phylogenetic analyses did not reveal any interpretable biogeographic patterns within the genus (e.g., K. spermatiophora from the tropical oceanic island Maui, Hawaii, was sister to K. faroensis from temperate midcontinental Ohio in North America). Previously hypothesized relationships among groups of species were not substantiated in the phylogenetic analyses, and no intrageneric classification is recommended based on current knowledge.

PHYLOGENETIC AFFINITIES OF "CHANTRANSIA" STAGES IN MEMBERS OF THE BATRACHOSPERMALES AND THOREALES (RHODOPHYTA)1.

This study evaluated the phylogenetic relationship among samples of "Chantransia" stage of the Batrachospermales and Thoreales from several regions of the world based on sequences of two genes-the plastid-encoded RUBISCO LSU gene (rbcL) and the nuclear SSU ribosomal DNA gene (SSU rDNA). All sequences of "Chantransia macrospora" were shown to belong to Batrachospermum macrosporum based on both molecular markers, confirming evidence from previous studies. In contrast, nine species are now associated with "Chantransia pygmaea," including seven species of the Batrachospermales and two of the Thoreales. Therefore, the presence of "C. macrospora" in a stream can be considered reliable evidence that it belongs to B. macrosporum, whereas the occurrence of "C. pygmaea" does not allow the recognition of any particular species, since it is associated with at least nine species. Affinities of "Chantransia" stages to particular taxa were congruent for 70.5% of the samples comparing the rbcL and SSU analyses, which were associated with the same or closely related species for both markers. Sequence divergences have been reported in the "Chantransia" stage in comparison to the respective gametophyte, and this matter deserves further attention.

SYSTEMATICS OF THE BATRACHOSPERMALES (RHODOPHYTA)-A SYNTHESIS(1).

Recent molecular and morphological data necessitate a major taxonomic revision of the Batrachospermales, an order of red algae, distributed in freshwater habitats throughout the world. This article is a synthesis of available information with some targeted additional sequence data, resulting in a few relatively conservative taxonomic changes to begin the process of creating a natural taxonomy for the Batrachospermales. To increase the information content of our taxonomic categories, and in particular to reduce paraphyly, we describe one new genus (Kumanoa) and a new section in Batrachospermum (section Macrospora), and we amend the circumscriptions of the family Batrachospermaceae (to include Lemaneaceae and Psilosiphonaceae), the genus Batrachospermum (to exclude the sections Contorta and Hybrida, raised to genus level as Kumanoa), and the sections Aristata, Helminthoidea, and Batrachospermum of Batrachospermum. We also provide a new name, B. montagnei, for the illegitimate B. guyanense, and recognize an informal paraphyletic grouping of taxa within Batrachospermum, the "Australasica Group." This taxonomic synthesis increases the level of monophyly within the Batrachospermales but minimizes taxonomic change where data are still inadequate.

PHYLOGEOGRAPHY OF BATRACHOSPERMUM MACROSPORUM (BATRACHOSPERMALES, RHODOPHYTA) FROM NORTH AND SOUTH AMERICA(1).

Phylogeographic trends in Batrachospermum macrosporum Mont. were investigated using the mitochondrial intergenic spacer between the cytochrome oxidase subunit 2 and 3 genes (cox2-3). A total of 11 stream segments were sampled with seven in the coastal plain of North America and four in tropical areas of South America. Fifteen thalli were sampled from seven streams, 14 thalli from two streams, and eight thalli from two streams. There were 16 haplotypes detected using 149 individuals. Of the eight haplotypes from locations in North America, all were 334 base pairs (bp) in length, and of those from South America, five were 344 bp, and three were 348 bp. Two individual networks were produced: one for the haplotypes from North America and another for those from South America, and these could not be joined due to the large number of base pair differences. This split between haplotypes from North and South America was confirmed with sequence data of the rbcL gene. There was very little genetic variation among the haplotypes from the North American locations, leading us to hypothesize that these are fairly recent colonization events along the coastal plain. In contrast, there was high variation among haplotypes from South America, and it would appear that the Amazon serves as a center of diversity. We detected considerable variation in haplotypes among streams, but frequently, a single haplotype in an individual stream segment, which is consistent with data from previous studies of other batrachospermalean taxa, may suggest a single colonization event per stream.

Kinetic study of the plastoquinone pool availability correlated with H2O2 release in seawater and antioxidant responses in the red alga Kappaphycus alvarezii exposed to single or combined high light, chilling and chemical stresses.

Under biotic/abiotic stresses, the red alga Kappaphycus alvarezii reportedly releases massive amounts of H(2)O(2) into the surrounding seawater. As an essential redox signal, the role of chloroplast-originated H(2)O(2) in the orchestration of overall antioxidant responses in algal species has thus been questioned. This work purported to study the kinetic decay profiles of the redox-sensitive plastoquinone pool correlated to H(2)O(2) release in seawater, parameters of oxidative lesions and antioxidant enzyme activities in the red alga Kappaphycus alvarezii under the single or combined effects of high light, low temperature, and sub-lethal doses of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which are inhibitors of the thylakoid electron transport system. Within 24 h, high light and chilling stresses distinctly affected the availability of the PQ pool for photosynthesis, following Gaussian and exponential kinetic profiles, respectively, whereas combined stimuli were mostly reflected in exponential decays. No significant correlation was found in a comparison of the PQ pool levels after 24 h with either catalase (CAT) or ascorbate peroxidase (APX) activities, although the H(2)O(2) concentration in seawater (R=0.673), total superoxide dismutase activity (R=0.689), and particularly indexes of protein (R=0.869) and lipid oxidation (R=0.864), were moderately correlated. These data suggest that the release of H(2)O(2) from plastids into seawater possibly impaired efficient and immediate responses of pivotal H(2)O(2)-scavenging activities of CAT and APX in the red alga K. alvarezii, culminating in short-term exacerbated levels of protein and lipid oxidation. These facts provided a molecular basis for the recognized limited resistance of the red alga K. alvarezii under unfavorable conditions, especially under chilling stress.