Wayne B. Chiasson

SYSTEMATICS of THE BATRACHOSPERMALES (RHODOPHYTA) - A SYNTHESIS

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.

Phylogenetic affinities of the form taxon Chantransia pygmaea (Rhodophyta) specimens from the Hawaiian Islands

W.B. Chiasson, K.G. Johanson, A.R. Sherwood and M.L. Vis. 2007. Phylogenetic affinities of the form taxon Chantransia pygmaea (Rhodophyta) specimens from the Hawaiian islands. Phycologia 46: 257–262. DOI: 10.2216/06-79.1 Eleven specimens attributable to the form taxon Chantransia pygmaea were collected from locations on the four main islands in Hawaii to assess their phylogenetic affinities. Partial rbcL sequence data were used to examine the relationship of these specimens to members of the Batrachospermales and Thoreales. Morphometric data from all specimens and mitochondrial cox2–3 spacer region data from specimens from three localities were used to determine variation within this form taxon. Three closely related haplotypes represented by nine specimens were recovered from locations on Kauai, Oahu and Hawaii. These haplotypes were sister to gametophytes of the batrachospermalean taxon Batrachospermum arcuatum from various locations worldwide. The two specimens from Maui were identical in sequence to each other and to a GenBank accession of Nemalionopsis tortuosa in the Thoreales. Morphometic analyses showed variation in measurements among specimens, but no clear pattern to distinguish C. pygmaea specimens associated with these two taxa. The cox2–3 spacer data from individual tufts at three locations (one stream each on the islands of Oahu, Kauai and Hawaii), representing the three rbcL haplotypes, did not differ within a location and showed the same relationships as in the rbcL data. On the basis of phylogenetic analyses, it appears that the region of origin for the B. arcuatum chantransia is East Asia, whereas N. tortuosa came from North America. Although taxa of the Batrachospermales have been previously reported from the Hawaiian Islands, this is the first record of a member of the Thoreales. With the addition of data from this study, the form taxon Chantransia pygmaea is now unequivocally associated with five taxa, B. ambiguum, B. arcuatum, B. atrum, N. tortuosa and Thorea violacea, through sequence data and culture studies.

Investigation of the molecular and morphological variability in Batrachospermum arcuatum (Batrachospermales, Rhodophyta) from geographically distant locations

Vis M.L., Feng J., Chiasson W.B., Xie S.-L., Stancheva R., Entwisle T.J., Chou J.-Y. and Wang W.-L. Investigation of the molecular and morphological variability in Batrachospermum arcuatum (Batrachospermales, Rhodophyta) from geographically distant locations. Phycologia 49: 545–553. DOI: 10.2216/10-04.1 Phylogeographic patterns in Batrachospermum arcuatum were investigated using the mitochondrial intergenic spacer between the cytochrome oxidase subunit 2 and 3 (cox2-3 spacer) from locations worldwide. Sixteen locations were sampled in six regions as follows: three locations in Bulgaria, two in China, three in the northwestern United States, one in New Zealand, six in Hawaii and one in Taiwan. Sequencing of 107 individuals resulted in 12 haplotypes. In the United States and Bulgaria, there was considerable sequence divergence among haplotypes. Likewise in the Hawaiian Islands, there was variation among haplotypes, and each island appeared to have a single haplotype represented. Three closely related haplotypes were present at the Taiwan location. The New Zealand sample was identical to one of the haplotypes from the northwestern United States. Individuals representing the 12 cox2-3 spacer haplotypes were sequenced for the rbcL gene. In the combined analysis, the Hawaii and Taiwan samples were a well-supported clade as were two Bulgaria samples. The US and New Zealand haplotypes formed a well-supported clade and likewise the China samples, but the relationship of the third Bulgaria haplotype to these others was unresolved. The specimens showed morphological variation among localities and regions, but no morphological features appeared to be diagnostic of the molecular results. Batrachospermum arcuatum appears to be a widespread taxon with considerable morphological plasticity that does not coincide with the substantial molecular variation. Alternatively, B. arcuatum may harbour cryptic species. There appears to be a temperate origin of the taxon and a derived group of haplotypes from tropical regions.

Phylogenetic relationship of Batrachospermum species (Batrachospermales, Rhodophyta) from coastal streams in French Guiana

M.L. Vis, W.B. Chiasson and R.G. Sheath. 2005. Phylogenetic relationship of Batrachospermum species (Batrachospermales, Rhodophyta) from coastal streams in French Guiana. Phycologia 44: 441–446. Eighteen samples of eight Batrachospermum species from collections in French Guiana, South America, were analysed utilizing RUBISCO large subunit (rbcL) gene sequence data in order to assess phylogenetic placement and evaluate intra-specific sequence variation among continents. Five species, B. ambiguum (two samples), B. gracillimum, B. guyanense, B. intortum and B. nodiflorum (two samples), belong to section Contorta. Section Aristata was represented by B. macrosporum (six samples) and B. cayennense (three samples) and Section Turfosa by B. turfosum (two samples). Maximum parsimony, distance, maximum likelihood and Bayesian analyses produced phylogenetic trees with similar topologies. The species from section Contorta were in a well-supported clade with previously sequenced taxa of that section. However, the subsectional classification sometimes applied to this section was not supported by the molecular data. Samples of B. macrosporum and B. cayennense were sister to each other, but they were on long branches and there was only moderate support in the Bayesian analyses for this node. Potentially, the two subsections of section Aristata may be raised to sectional status with further investigation of other closely related taxa. Batrachospermum turfosum is the only species presently sequenced from section Turfosa and these samples formed a well-supported clade on a long branch, which was variously related to other batrachospermalean taxa in the analyses. Three of the species, B. ambiguum, B. cayennense and B. macrosporum, showed little to no variation within species for the French Guiana samples, but varied considerably from previously published sequences of samples from different continents. In contrast, the B. turfosum samples differ little from a North American sample.

Phylogeography of a freshwater red alga, Batrachospermum helminthosum, in North America

Abstract The mitochondrial DNA region consisting of the intergenic spacer between the cytochrome oxidase subunit 2 and cytochrome oxidase subunit 3 genes with the flanking gene regions (cox2–3) was used to investigate phylogeographic trends among populations of Batrachospermum helminthosum. Thirteen stream segments throughout the range of this taxon in North America were sampled as follows: four in Ohio, two in Michigan and one each in Connecticut, Indiana, Louisiana, Massachusetts, North Carolina, Rhode Island and Tennessee. Fifteen thalli per stream reach were analysed except for OH1 in which 54 individuals were studied. Thirteen haplotypes were detected among the 234 individuals sequenced from the 13 locations. One location (TN) had four haplotypes, six locations (OH1, 2, 3, CT, NC, MA) had two haplotypes and the remaining six (OH4, MI1, 2, IN, LA, RI) had only one. Only four of the haplotypes were shared among two or more locations. Even though haplotypes were mainly confined to one stream segment, many of them differed by only 1–3 bp. Phylogenetic analyses showed two divergent lineages: the first contained 10 of the 13 haplotypes from MA, RI, CT, OH (1–3), NC, IN, LA and TN locations; the second contained one haplotype from TN, and two other haplotypes from the OH4 location and the two MI locales. It would appear that genetically similar haplotypes dominate much of the range of B. helminthosum. We hypothesize that dispersal via small streamside-dwelling birds may be the mechanism to explain this pattern. The Tennessee location is interesting in that it had twice as many haplotypes as the other locations (even OH1 with 54 individuals sampled). This result may be due to multiple colonization events at that stream by genetically heterogeneous individuals or alternatively, this population could be more ancient than the others with this location serving as a mountain refugium during the last glaciation.

Affinities of freshwater putative chantransia stages (Rhodophyta) from molecular and morphological data

W.B. Chiasson, N.J. Sabo and M.L. Vis. 2005. Affinities of freshwater putative chantransia stages (Rhodophyta) from molecular and morphological data. Phycologia 44: 163–168. Fourteen putative bluish chantransia isolates were collected from locations in French Guiana (9), Brazil (1), Bolivia (1) from South America, and Mississippi, USA (3) in North America. Morphometric analyses were conducted on all isolates and partial (1282 bp) rbcL gene sequence data were obtained from 11 specimens. One isolate fit the morphological description of Audouinella pygmaea or ‘Chantransia pygmaea’ and had smaller cell dimensions and monosporangium diameter than the other isolates. The other 10 specimens varied in morphology, but were within the circumscription of A. macrospora or ‘C. macrospora’. Sequence data confirmed that the ‘pygmaea’ isolate was the chantransia of Batrachospermum ambiguum and the ‘macrospora’ isolates were chantransia of B. macrosporum. The results of this study strongly support that ‘C. macrospora’ represents a single species, B. macrosporum, but only a small number of freshwater red algal taxa have been analysed using either culture or genetic data, and more taxa with this chantransia morphology may be found. With only the present gene sequence data, it is difficult to ascertain whether the ‘pygmaea’ morphology represents only the chantransia of B. ambiguum or, more likely, numerous species. The B. macrosporum chantransia was in numerous streams in which no gametophytes of this taxon were collected, but gametophytes of other Batrachospermum species were present. Therefore, caution should be used in assuming that the macroscopic chantransia in a stream is the alternate life history phase of the gametophytes present. There was sequence variation among the B. macrosporum chantransia isolates and even between a chantransia isolate and gametophyte from the same stream segment, possibly suggesting that the diploid chantransia may serve as a repository for genetic variation.

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.