Timothy J. Entwisle

PHYLOGENY OF THE BATRACHOSPERMALES (RHODOPHYTA) INFERRED FROM rbcL AND 18S RIBOSOMAL DNA GENE SEQUENCES

The sequence data from the large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (rbcL) gene and 18S ribosomal DNA (small subunit) of taxa in the freshwater rhodophyte order Batrachospermales were used to construct phylogenetic hypotheses. Taxa examined in this study represent four families, eight genera, and six sections of the genus Batrachospermum. In addition, Rhododraparnaldia oregonica Sheath, Whittick et Cole, was included in the analysis because it shares particular ultrastructural, reproductive, and morphological characteristics with members of the Batrachospermales and Acrochaetiales. The trees generated from each gene, as well as a combined data set, were largely congruent. Rhododraparnaldia consistently occurs on an early branch within the Acrochaetiales–Palmariales clade and does not appear to be a member of the Batrachospermales. In addition,Thorea violacea Bory de St. Vincent was not closely related to the other taxa of the Batrachospermales in all trees and hence the family Thoreaceae does not appear to be a natural grouping within this order. All other taxa analyzed, which are presently classified within this order, formed a monophyletic clade in most analyses. Psilosiphon scoparium Entwisle was not closely allied with the taxa of the Lemaneaceae, lending support to the newly proposed family Psilosiphonaceae. Sequence data from the remaining taxa of the Lemaneaceae support the concept of a derived monophyletic clade. The genus Batrachospermum appears to comprise many morphologically similar but distantly related taxa, which will need further investigation to resolve their taxonomic status. Tuomeya, Sirodotia and Nothocladus are retained at the generic level until further data are obtained.

INSIGHTS INTO THE PHYLOGENY OF THE BATRACHOSPERMALES (RHODOPHYTA) FROM rbcL SEQUENCE DATA OF AUSTRALIAN TAXA

Thirteen representatives of the freshwater red algal order Batrachospermales from Australia were analyzed with previously published sequences in a phylogenetic analysis of RUBISCO large subunit (rbcL) gene sequence data. The newly sequenced taxa represented putative endemics to the Australia–New Zealand region (Batrachospermum antipodites, B. deminutum, B. discors, B. kraftsii, B. theaquum, B. wattsii, and Nothocladus lindaueri) and more cosmopolitan species (B. ambiguum, B. atrum, B. cayennense, B. gelatinosum[two samples], and Sirodotia suecica). From parsimony, distance, and maximum likelihood analyses, three clades of batrachospermalean taxa were suggested: a “mixed” clade composed of taxa sampled from Australia and North America, a clade of primarily Australian collections, and a clade of predominantly North American samples. The latter two clades appeared to be more closely related to each other than to the mixed clade. It is hypothesized that the Australian clade may be of Gondwanic origin, but more sampling of other continents is needed to confirm this statement. The collections of B. gelatinosum from Australia did not form a monophyletic clade with B. gelatinosum from North America, and a new species, B. pseudogelatinosum, is proposed for the Australian collections. Unlike the B. gelatinosum results, B. atrum and S. suecica samples from Australia were very closely related to collections of the same species from other continents. With the addition of B. deminutum and B. ambiguum to the analysis, Batrachospermum section Contorta is shown to be monophyletic if section Hybrida is included. The expansion of the description for section Contorta is proposed to accommodate species from section Hybrida. The validity of Batrachospermum section Aristata is questioned based on the distant relationship of B. macrosporum and B. cayennense.

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.

Contrasting intra versus interspecies DNA sequence variation for representatives of the Batrachospermales (Rhodophyta): Insights from a DNA barcoding approach

Sixty‐five accessions of the species‐rich freshwater red algal order Batrachospermales were characterized through DNA sequencing of two regions: the mitochondrial cox1 gene (664 bp), which is proposed as the DNA barcode for red algae, and the UPA (universal plastid amplicon) marker (370 bp), which has been recently identified as a universally amplifying region of the plastid genome. upgma phenograms of both markers were consistent in their species‐level relationships, although levels of sequence divergence were very different. Intraspecific variation of morphologically identified accessions for the cox1 gene ranged from 0 to 67 bp (divergences were highest for the two taxa with the greatest number of accessions; Batrachospermum helminthosum and Batrachospermum macrosporum); while in contrast, the more conserved universal plastid amplicon exhibited much lower intraspecific variation (generally 0–3 bp). Comparisons to previously published mitochondrial cox2–3 spacer sequences for B. helminthosum indicated that the cox1 gene and cox2–3 spacer were characterized by similar levels of sequence divergence, and phylogeographic patterns based on these two markers were consistent. The two taxa represented by the largest numbers of specimens (B. helminthosum and B. macrosporum) have cox1 intraspecific divergence values that are substantially higher than previously reported, but no morphological differences can be discerned at this time among the intraspecific groups revealed in the analyses. DNA barcode data, which are based on a short fragment of an organellar genome, need to be interpreted in conjunction with other taxonomic characters, and additional batrachospermalean taxa need to be analyzed in detail to be able to draw generalities regarding intraspecific variation in this order. Nevertheless, these analyses reveal a number of batrachospermalean taxa worthy of more detailed DNA barcode study, and it is predicted that such research will have a substantial effect on the taxonomy of species within the Batrachospermales in the future.

Morphometric analysis of Batrachospermum section Batrachospermum (Batrachospermales, Rhodophyta) type specimens

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...

Majority rules, when systematists disagree

The creation of Australia’s Virtual Herbarium forced the Australian plant systematics community to find a mechanism for deciding between alternative taxonomies. Following a workshop on the Orchidaceae and the publication of some simple draft guidelines, a set of ‘rules of thumb’ are presented here that we believe represent the view of most practising systematists. Not everyone will agree, and we have provided alternative views where possible. We include the need for monophyletic taxa, minimising taxonomic change, understanding that some taxa have strong ‘interest groups’, making it clear that ‘preferred name’ does not necessarily imply ‘best name’ on all criteria, avoiding epithets used in possible congeners, and the concept of ‘majority rules’ when states and territories have differing views.

A re‐examination of the morphology, ultrastructure and classification of genera in the Lemaneaceae (Batrachospermales, Rhodophyta)

Vegetative and reproductive morphology and ultrastructure were examined for the three genera of the freshwater red algal family Lemaneaceae: Lemanea (two species, seven populations), Paralemanea (two species, three populations) and Psilosiphon (one species, one population). Psilosiphon is readily distinguished from the other two genera in having an outer cortex composed of well‐defined filaments interconnected with a dense medulla (both cell types being little vacuolated), spores cleaving off obliquely, putative spermatangia scattered on the thallus surface and reproduction by adventitious filaments. Based on the distinctness of this genus (and corroborated by molecular phylogenies in preparation), a new family is described, the Psilosiphonaceae. Lemanea and Paralemanea appear to be closely related, with an outer cortex that has cells of increasing size and vacuolation from the periphery to the interior and not in obvious rows, a central lumen that contains few ray cells but no medullary filaments, sexual reproduction with spermatangia in distinct clusters, and carpospores in chains, some of which can germinate in the thallus lumen. Lemanea and Paralemanea have distinguishing characteristics that the other genus does not: for Lemanea, hair cells, ray cells abutting the outer cortex and spermatangia in patches; for Paralemanea, no hair cells or ray cells appressed to the outer cortex, inner cortical filaments surrounding the central axis and spermatangia in rings.

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.

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.

Ptilothamnion richardsii (Rhodophyta) is a chantransia stage of Batrachospermum

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 to these is provided.