Carolyn J. Bird

A preliminary investigation of the order Bangiales (Bangiophycidae, Rhodophyta) based on sequences of nuclear small‐subunit ribosomal RNA genes

We investigated phylogenetic relationships among red algae of the order Bangiales by analysis of sequences of the nuclear gene encoding cytosolic small‐subunit ribosomal RNA in Bangia atropurpurea (Roth) C. Ag. and eight samples representing seven species of Porphyra. The ssu‐rDNA range from 1818 to 1845 nucleotides in length, with guanosine plus cytosine ratios between 47.0% and 48.6%. A group IC1 intron occurs in the B atropurpurea ssu‐rDNAs at the same position as in P. spiralis var. amplifolia Oliveira Filho et Coll and several other eukaryote ssu‐rDNAs. The nine sequences form a stable monophyletic group upon phylogenetic analysis. The ssu‐rDNA from B. atropurpurea nests stably within the Porphyra group and is closely related to P. amplissima (Kjellm.) Setchell et Hus in Hus, making the genus Porphyra paraphyletic. No correlation is seen between phylogenetic position and number of cell layers in the Porphyra thallus. We discuss possible taxonomic and evolutionary implications of these observations.

Molecular relationships among the Gracilariaceae (Rhodophyta): further observations on some undetermined species

We have used molecular characteristics to clarify the taxonomic status of three problematic gracilarioid algae, by comparison with existing data for the Gracilariaceae. Nucleotide sequences of nuclear-encoded 18S rDNA were determined for an unidentified species of Gracilariopsis from North Carolina, and two infertile strains of gracilarioid algae from Namibia, tentatively assigned to Gracilariopsis. The sequence from the North Carolinian alga was intermediate between those established previously for Gracilariopsis lemaneiformis and European Gracilariopsis sp., and represents a different, probably undescribed, species. Sequences from the Namibian plants were characteristic of Gracilaria, and very similar to those from Gracilaria verrucosa and two closely related congeners. In parsimony, distance and maximum-likelihood analyses of these sequences and others already published for the Gracilariaceae, the North Carolinian Gracilariopsis sp. consistently grouped with its congeners, and the two Namibian strains ...

A review of recent taxonomic concepts and developments in the Gracilariaceae (Rhodophyta).

Despite much effort in the past decade to resolve the taxonomy of algae in the Gracilariaceae, the family remains problematic. Genetic concepts have become equivocal as their diagnostic reproductive features have been reported as mixed in single species. Species concepts are often also uncertain since the full phenotypic range of a species is seldom known or appreciated. This paper reviews some of the recent taxonomic controversy from the viewpoints of morphology and molecular biology. As more observations are made, features like spermatangial configuration and mode of gonimoblast nutrition, once considered characteristic of genera and subgenera, are emerging as a continuum of types that may vary within species. Culture studies to establish the reproductive anatomy of a life history and to test crossabilities are invaluable to species concepts but also may yield false results owing to clonal variability and intraspecific sterility. Characteristics of DNA have been effective in clarifying some aspects of gracilariacean taxonomy and phylogeny, and may be able to resolve the major inconsistencies if more widely applied.

A molecular investigation of polymorphism in the North Atlantic red alga Chondrus crispus (Gigartinales)

Seven samples of Chondrus crispus Stackhouse, representing widely contrasting forms from both sides of the North Atlantic, were compared by restriction digestion of their plastid DNA. The similar banding patterns confirmed that the seven forms were conspecific and distinct from Chondrus ocellatus Holmes f. ocellatus from Japan, used as an outgroup. Nucleotide sequences of the internal transcribed spacers (ITS1 and ITS21 and the intervening 5.8S rRNA gene of the nuclear rRNA operon were investigated as a potential indicator of genetic divergence among morphological variants of C. crispus. The combined ITS regions were relatively short in Chondrus (between 719 and 731 base pairs [bp] in C. crispus and 724 bp in C. ocellatus f. ocellatus), and the sequence of the 5.8s rDNA fragment (152 bp) was identical in both species. In the aligned ITS regions, there were 0–18 base pair differences (0–2.18% divergence) in pairwise comparisons of the seven forms of C. crispus but no consistent pattern of variation according to gross morphology or geographic origin. However, the ITS sequence differed at 41–54 sites (6.22‐7.56%) between C. crispus and C. ocellatus f. ocellatus, again illustrating the genetic distinctiveness of the latter species.

Nucleotide sequences of 18S ribosomal RNA genes from the red algae Gracilaria tikvahiae McLachlan, Gracilaria verrucosa (Hudson) Papenfuss and Gracilariopsis sp.

Owing especially to intensive aquaculture in recent years, marine red algae of the family Gracilariaceae have become the major source of agar in the international market. However, because of a high degree of morphological similarity among gracilariacean algae, and morphological plasticity within populations, identification and classification of these algae are often problematic. These difficulties greatly complicate assessment of natural agarophyte stocks, and may raise problems for regulatory approval of agars. Gracilaria tikvahiae McLachlan is the most thoroughly characterized of the hundred-odd described species of Gracilaria, and belongs to the subgenus Textoriella. Gracilaria verrucosa (Hudson) Papenfuss is a widely distributed, economically important species, and is the type of the other (nominate) subgenus. The verrucosa species concept has, however, recently been shown to comprise a number of similar taxa (1). Using organellar DNA restriction profiles, we have identified an assemblage of chiefly European strains conforming to the current concept of G. verrucosa (2); the G. verrucosa nuclear smallsubunit (18S) rDNA sequence below represents one of these strains, from Oslo, Norway. Species recognition has been further complicated by the discovery in the G. verrucosa type locality of an as yet unidentified species of the related genus Gracilariopsis (3) which has frequently been mistaken for G. verrucosa, therefore may be included in the original species concept (2). To assist in characterizing this Gracilariopsis sp., we have determined the sequence of its 18S rDNA for comparison with that recently

PHYLOGENETIC RELATIONSHIPS OF SPECIES OF UNCERTAIN TAXONOMIC POSITION WITHIN THE ACROCHAETIALES‐PALMARIALES COMPLEX (RHODOPHYTA): INFERENCES FROM PHENOTYPIC AND 18S rDNA SEQUENCE DATA1

Nucleotide sequences of the small‐subunit ribosomal RNA gene (18S rDNA)were newly determined for four members of the related rhodophyte orders Palmariales and Acrochaetiales and were compared by neighbor‐joining and parsimony analyses with four previously published sequences from these orders. A published rDNA sequence from Nemalion helminthoides (Velley in Withering) Batters (Nemaliales)and a gene sequence determined herein for Nothocladus nodosus Skuja (Batrachospermales) were used as outgroups. Sequences were very similar within the Palmariales with a maximum difference of 13 nucleotides out of 1772 between members of the families Palmariaceae and Rhodophysemataceae. Despite similarities in life history, the acrochaetioid algae Rhodo‐chorton purpureum (Lightfoot) Rosenvinge and Rhodothamniella floridula (Dillwyn)J. Feldmann in Christensen were phylogenetically separated with R. purpureum affiliated weakly with Acrochaetiales, and R. floridula forming a sister branch unequivocally to palmarialean algae of the families Rhodophysemataceae and Palmariaceae. Rhodothamniella floridula is postulated on both molecular and phenotypic grounds (encompassing biochemical and anatomical characters, and life history features)to represent an early lineage, Rhodothamniellaceae fam. nov., in the Palmariales. The family Rhodophysemataceae appeared paraphyletic in the sequence analyses, but a monophyletic Rhodophysemataceae could not be rejected by Templeton‐Felsenstein or Kishino‐Husegawa tests, and the family was clearly monophyletic in analysis of the phenotypic data. The earlier tentative placement of Rhodophysemataceae in the Palmariales rather than Acrochaetiales was confirmed.

Biology of Furcellaria lumbricalis (Hudson) Lamouroux (Rhodophyta: Gigartinales), a commercial carrageenophyte

Information on the commercially utilized marine red alga Furcellaria lumbricalis is summarized from published sources. Biological aspects under discussion include: nomenclature, taxonomy, morphology, development and life history, distribution, phenology, ecophysiology, growth and resource management. A brief history of the utilization of this species, and an account of its chemical constituents including the hydrocolloid furcellaran are also presented.

A critical comparison ofGracilaria chilensis andG. sordida (Rhodophyta, Gracilariales)

Gracilaria chilensis Bird, McLachlanet Oliveira from Chile andG. sordida Nelson from New Zealand have been compared with respect to reproductive anatomy, chromosome number, interfertility, and organellar DNA restriction profiles. No differences were found in reproductive anatomy, which in these species is distinguished by deeptextorii-type spermatangial conceptacles and prominent tubular nutritive cells directed only to the floor of the cystocarp. The species share a chromosome number ofn = 24 and are readily interfertile. Electrophoretic profiles of organellar DNA digested with four different restriction endonucleases were virtually identical between the species except for bands that represented accompanying plasmids. However, previous research has indicated that the four plasmid bands inG. chilensis and the single one inG. sordida have a common origin. On these groundsG. chilensis andG. sordida are

Recommended names of included species of Gracilariaceae

The following list includes the species that are mentioned in the review papers given at the Workshop on Gracilaria and its Cultivation and included in this issue. The list is nomenclatural and not taxonomic; more information on the group can be found in one of the reviews (Bird, 1995). We emphasize that the synonymy in the list is not complete and is intended only to indicate misnomers that have become entrenched though usage. Recommended names are shown in bold face and synonyms or misapplied names in normal italics. Each indented name applies to the unindented, alphabetically arranged, name above it. When the synonymy or other usage is specific to a geographic location, the country or area is given. G. = Gracilaria; s = Gracilariopsis; (?), records from the region tentative or dubious.

The 18S rRNA gene sequences of four commercially important seaweeds

Abstract18S rRNA gene sequences are presented forAhnfeltia plicata, Chondrus crispus, Furcellaria lumbricalis andPalmaria palmata, commercially important marine algae of the North Atlantic. The sequences range from 1765 to 1777 nucleotides in length, with guanine + cytosine content of 50.1% to 52.4%. Sequence divergence between species in different orders was 11.3–12.3%, whereas the variation betweenC. crispus andF. lumbricalis, both from the Gigartinales, was only 3.6%. Based on limited experience with other groups of Rhodophyta, these sequences obtained from single populations are likely to be representative of the species as a whole, with little variation expected among conspecifics regardless of morphological aberration or apparent genetic isolation.