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Twenty-five specimens of the freshwater red alga Compsopogon were collected from locations in North America, South America, Europe, Asia, Australasia and Oceania, and from an aquarium, with the goal of determining genetic diversity among specimens and ascertaining the number of phylogenetic species. Specimens were morphologically identified as having either the ‘caeruleus’ morphology, with regular polyhedral cortical cells, or the ‘leptoclados’ morphology, with irregular cortical cells with rhizoidal outgrowths. The ‘leptoclados’ morphology has been used by some researchers to distinguish the genus Compsopogonopsis from Compsopogon, or at least to distinguish C. leptoclados from other Compsopogon species. Sequence data for the rbcL gene and cox1 barcoding region were obtained for most specimens. In addition, SSU and partial LSU (barcode) rDNA were explored for a few specimens, but all sequences were identical. For the 25 newly generated and eight previously published rbcL gene data, there were seven uniqu...

Species level taxonomy and phylogeographical distribution patterns in the freshwater rhodophyte Sirodotia are resolved through phylogenetic inferences based on rbcL and cox2–3 sequence data. Previous studies focused on the taxonomy of specific Sirodotia species or the distributions across a limited geographical region. Our molecular phylogenies included samples attributable to five recognized Sirodotia species and include collections from Australia, Brazil, Costa Rica, Canada, Finland, Mexico, New Zealand, South Africa and the United States. Both rbcL and cox2–3 phylogenies inferred S. suecica, S. tenuissima and S. goebelii as a monophyletic group with little sequence divergence. This result supports the synonymy of S. tenuissima and S. goebelii with S. suecica (the species name with priority). Within this clade, samples collected from Australia and New Zealand formed a monophyletic group with no other discernible phylogeographical patterns within S. suecica. This result seems to be somewhat unusual in th...

Four specimens attributable to the freshwater red algal taxon, Ptilothamnion richardsii, were examined from locations in Australia and French Guiana, and partial rbcL gene sequence data were obtained. Phylogenetic analyses showed these specimens to be allied to taxa in the Batrachospermales. The two specimens from Australia were determined to be Batrachospermum antipodites, differing from that taxon by only 15 bp (1.2%). The two specimens from French Guiana were within the Batrachospermum section Contorta clade, but differed considerably (≥8%) from the taxa for which there are presently rbcL gene data. The sequence data clearly show these specimens to be chantransia stages of Batrachospermum taxa. Recently, other described freshwater Audouinella taxa have also been shown to be chantransia stages. Like previous authors, we argue that it is useful to continue to recognize entities with particular morphological characters and propose the form taxa Chantransia richardsii, C. macrospora and C. pygmaea. A key t...

Four populations of the newly described freshwater red algal species Batrachospermum spermatoinvolucrum were sampled from British Columbia on the west coast of North America and Labrador on the east. The rDNA internal transcribed spacer (ITS) 1 and 2 sequences, RUBISCO large subunit (rbcL) gene data for three of the populations and morphometric characteristics were compared with those of B. gelatinosum. In addition, the key feature distinguishing B. spermatoinvolucrum, spermatangia on the involucral filaments of the carpogonial branch, was investigated seasonally in one British Columbia population of this species. The ITS analysis suggested that the B. spermatoinvolucrum populations were more closely related to particular B. gelatinosum populations than to each other and did not form a monophyletic clade. Two populations of B. spermatoinvolucrum from Labrador and British Columbia had identical rbcL sequences that were distinct from that of B. gelatinosum. However, the rbcL sequence from the third populati...

Sixty-two North American populations of seven previously described species belonging to Batrachospermum sect. Batrachospermum were examined and compared with appropriate type specimens using morphometrics and image analysis. All populations were similar to the respective type specimens in qualitative and quantitative characteristics, but the range of some morphological features has been extended. B. boryanum was the most abundant and widespread species, being collected in 34 stream sites from Newfoundland and British Columbia in the north to Georgia in the south. The other six species — B. anatinum, B. arcuatum, B. confusum, B. heterocorticum, B. pulchrum and B. skujae — were more localized and occurred in six or fewer streams. B. anatinum was restricted to Missouri, Arkansas and Virginia and B. arcuatum was collected in western North America from Alaska to Mexico. The distribution of B. confusum was disjunct, with populations occurring in Alberta, Quebec, Newfoundland, Maine and Missouri. B. heterocortic...

Eighty-six populations of Batrachospermum gelatinosum were examined from throughout its known range in North America and were compared using multivariate morphometrics and image analysis. Morphological variability was as great in individual populations as that measured among locations. Populations pooled for each biome showed a north-south trend in whorl and carpogonium size. The mean measurements for the tundra were significantly smaller in whorl diameter and larger in carpogonium size than those for the coastal plain. B. gelatinosum is widely distributed in North America, having been collected from the north slope of Alaska and Baffin Island in the north to Texas and Louisiana in the south. In addition to the populations analysed, herbarium specimens from North America were examined and confirmed locations in 17 US states, four Canadian provinces and the Yukon territory were added. Three populations, two from the boreal forest (Newfoundland) and one from the deciduous forest (Rhode Island), were examine...

Type and historically important specimens of 46 species and infraspecific taxa from Batrachospermum sect. Batrachospermum were examined. Of these, 48 specimens of 33 taxa were compared using multivariate morphometrics and image analysis. Nine species from the cluster analysis and one other species are recognised: B. anatinum, B. arcuatum, B. boryanum, B. carpocontorum, B. confusum, B. fluitans, B. gelatinosum, B. heterocorticum, B. pulchrum and B. skujae, B. ectocarpum is considered to be synonymous with B. anatinum, rather than with B. boryanum or B. arcuatum as has been proposed by previous authors. The illegitimately named species B. helminthosum Sirodot (non Bory) is referable to B. confusum as are B. crouanianum and B. fruticulosum. No varieties of B. gelatinosum could be supported and numerous taxa including B. pyramidale, B. densum and B. decaisneanum are synonymised within this species. The taxa in sect. Batrachospermum are separated on the basis of whether they are monoecious or dioecious, carpog...

North American populations and type specimens of Thorea and Nemalionopsis were compared using multivariate morphometrics and image analysis. We continue to recognise the separation of the two genera based on spore-bearing branch-to-assimilatory filament length ratio and assimilatory filament density (≤0·3 and loose for Thorea and ≥0·6 and compressed for Nemalionopsis, respectively). Four species of Thorea were distinguished worldwide: T. hispida (syn. T. andina, T. lehmannii, T. ramosissima), T. violacea (syn. T. bachmannii, T. brodensis, T. gaudichaudii, T. okadae, T. prowsei and T. riekei), T. clavata and T. zollingeri. The former two species have variable branched, non-clavate assimilatory filaments, whereas the latter two have unbranched, clavate assimilatory filaments. Thorea hispida has copious secondary branches while T. violacea is sparsely branched. Thorea clavata is differentiated from T. zollingeri by having fewer monosporangia per cluster. Two of these species were found in North America: T. h...