ITS1 sequences of type specimens of Gigartina and Sarcothalia and their significance for the classification of South African Gigartinaceae (Gigartinales,Rhodophyta)

Uncertainties about the identity of type specimens of red algae have frequently led to taxonomic and nomenclatural confusion. A procedure for extracting PCR-amplifiable DNA from formalin-fixed material and herbarium specimens was used to investigate the taxonomic status of several South African Gigartinaceae. We compared nucleotide sequences in the internal transcribed spacer 1 (ITS1) region in type specimens and other historically important collections presently referred to Gigartina bracteata, G. radula and G. stiriata. The following opinions are supported: (1) Fucus bracteatus S.G. Gmelin, Chondrodictyon capense Kützing and Iridaea clathrata Decaisne represent a single species of South African Gigartina (G. bracteata (S.G. Gmelin) Setchell & Gardner) in which the disintegration of tetrasporangial sori results in a reticulate thallus. (2) Mastocarpus polycarpus Kützing, M. incrassatus Kützing and Iridaea lapathifolia Kützing represent a single species of South African Gigartina (G. polycarpa (Kützing) Setchell & Gardner) that has often, but erroneously, been called G. radula (Esper) J. Agardh. (3) Mastocarpus verrucosus Kützing is a later heterotypic synonym of Iridaea papillosa Bory (Sarcothalia papillosa (Bory) Leister) and was based on material that probably came from southern South America rather than from South Africa, the provenance given by Kützing. (4) Fucus stiriatus Turner and Sphaerococcus burmannii C. Agardh represent a single species of South African Sarcothalia (S. stiriata (Turner) Leister).     

Chemotaxonomy of New Zealand red algae in the family Gigartinaceae (Rhodophyta) based on galactan structures from the tetrasporophyte life-stage

The identification of the polysaccharides from tetrasporophytic plants of nine endemic New Zealand species belonging to the Gigartinaceae, ‘Gigartina’ ancistroclada, ‘G.’ grandifida, Gigartina dilatata, G. divaricata, G. macrocarpa, G. marginifera, G. pachymenioides, G. sp. ‘Lindauer 164’ and Sarcothalia livida using infra-red spectroscopy in conjunction with constituent sugar and glycosyl linkage/substitution analysis is reported. All nine species contain galactans with structures consistent with λ-type carrageenans. Differences in the structures of the galactans in these and a further six previously studied species indicate chemotaxonomically distinct groupings that correspond to Sarcothalia, ‘Sarcothalia’ and Gigartina genera plus some outliers. These distinct, chemotaxonomic groupings are aligned to those determined by rbcL sequence analysis reported in the literature.     

DIFFERENTIATION OF LAMBDA CARRAGEENANS FROM RHODOPHYTA WITH IMMUNOLOGICAL AND SPECTROSCOPIC TECHNIQUES1

KCl soluble carrageenans from sporophytes of two Gigartina species were differentiated from those of Chondrus crispus Stackhouse, Iridaea cordata (Turner) Bory, Rhodoglossum californicum (J. Ag.) Abbott, and two Petrocelis species by their failure to precipitate on immunodiffusion against either of two absorbed anti-λ–carrageenan antisera. The carrageenans have been analyzed by infrared spectroscopy, and on this basis it is postulated that the antibody preparations recognize sulphate on C-6 of the carrageenans. The Gigartina carrageenans appear to lack sulfate at this position.     

SOLVING TAXONOMIC AND NOMENCLATURAL PROBLEMS IN PACIFIC GIGARTINACEAE (RHODOPHYTA) USING DNA FROM TYPE MATERIAL

Molecular data obtained by a procedure for extracting PCR-amplifiable nuclear and chloroplast DNA from old and formalin-fixed red algal herbarium specimens were used to elucidate problems in the systematics of Pacific Gigartinaceae. Correspondence between nucleotide sequences of the internal transcribed spacer 1 region or the RUBISCO spacer from type specimens and modern collections supports the following conclusions. (1) The type of Fucus cordatus Turner, now Iridaea cordata (Turner) Bory, came from the southern hemisphere (probably from Isla de los Estados, Argentina) rather than from Banks Island, B.C., Canada. (2) The type of Iridaea heterocarpa P. et R. [Mazzaella heterocarpa (P. et R.) Fred.] represents the tetrasporangial phase of a species of Chondrus, possibly C. crispus Stackh. (3) The types of Iridaea lilacina P. et R., I. phyllocarpa P. et R., and Iridophycus furcatum S. et G. represent a single species from Alaska, Mazzaella phyllocarpa (P. et R.) Perest., currently but incorrectly called M. heterocarpa. (4) The type of Iridophycus oregonum Doty represents the tetrasporangial phase of the species from southern Alaska to southern California known incorrectly as M. heterocarpa. (5) Mazzaella splendens (S. et G.) Fred. is more closely related to M. linearis (S. et G.) Fred. than it is to M. flaccida (S. et G.) Fred. (6) Iridophycus coriaceum S. et G. is conspecific with M. splendens, whereas Rhodoglossum coriaceum E.Y. Dawson is an independent species: Mazzaella coriacea (E.Y. Dawson) Hughey. (7) Iridaea cornucopiae P. et R. is conspecific with Mazzaella laminarioides (Bory) Fred., and the type probably came from Chile rather than from the North Pacific. (8) Plants attributed to Iridaea cornucopiae in Pacific North America are referable to Mazzaella parksii (S. et G.) comb. nov. (9) Rhodoglossum parvum G. M. Smith et Hollenb. is an independent species: Mazzaella parva (G. M. Smith et Hollenb.) comb. nov. (10) Grateloupia squarrulosa S. et G., Grateloupia johnstonii S. et G., and Gigartina pectinata E.Y. Dawson represent a single species: Chondracanthus squarrulosus (S. et G.) comb. nov.     

A phylogenetic re‐appraisal of the family Liagoraceae sensu lato (Nemaliales,Rhodophyta) based on sequence analyses of two plastid genes and postfertilization development

The marine red algal family Liagoraceae sensu lato is shown to be polyphyletic based on analyses of a combined rbcL and psaA data set and the pattern of carposporophyte development. Fifteen of eighteen genera analyzed formed a monophyletic lineage that included the genus Liagora. Nemalion did not cluster with Liagoraceae sensu stricto, and Nemaliaceae is reinstated, characterized morphologically by the formation of the primary gonimolobes by longitudinal divisions of the gonimoblast initial. Yamadaella and Liagoropsis, previously placed in the Dermonemataceae, are shown to be independent lineages and are recognized as two new families Yamadaellaceae and Liagoropsidaceae. Yamadaellaceae is characterized by two gonimoblast initials cut off bilaterally from the fertilized carpogonium and diffusely spreading gonimoblast filaments. Liagoropsidaceae is characterized by at least three gonimoblast initials cut off by longitudinal septa from the fertilized carpogonium. In contrast, Liagoraceae sensu stricto is characterized by a single gonimoblast initial cut off transversely or diagonally from the fertilized carpogonium. Reproductive features, such as diffuse gonimoblasts and unfused carpogonial branches following postfertilization, appear to have evolved on more than one occasion in the Nemaliales and are therefore not taxonomically diagnostic at the family level, although they may be useful in recognizing genera.     

Immunochemistry of kappa-type carrageenans from certain red algae

Carrageenans from female and male gametophytic plants of the alga Rhodo-glossum californicum, female plants of Chondrus crispus and Gigartina pistillata, and male plants of Iridaea cordata and a Gigartina species from San Francisco Bay were fractionated into potassium chloride-soluble and -insoluble components and were analysed chemically. An anti-K-carrageenan, the reactivity of which is directed to K-type structures (i.e., 3-linked d-galactose 4-sulphate and 4-linked 3,6-anhydro-D-galactose residues) was used to analyse these carrageenans immunochemically. The potassium chloride-insoluble carrageenans from these species were found to be highly reactive K-type carrageenans. The potassium chloride-soluble carrageenans were less reactive to anti-K-carrageenan and, in addition, showed reactivity to an anti-λ-carrageenan preparation. The chemical and immunochemical data suggest that the potassium chloride-soluble carrageenans contain either λ- or μ-carrageenan, as a high proportion of the precursors to the 3,6-anhydro-D-galactose are 4-linked D-galactose 2,6-disulphate residues, and no increase in immunological reactivity to anti K-carrageenan was observed upon alkali treatment.     

Reliability of the resorcinol method for identifying isomorphic phases in the Gigartinaceae (Rhodophyta)

The Gigartinaceae are economically important because the carrageenans in this family are used for a variety of purposes including food stabilizers, food substitutes, pharmaceutical applications and cosmetics. The resorcinol method takes advantage of the different carrageenans found in life history phases in this family to identify nonreproductive phases, and consequently, a better understanding of the biology of this economically important family is possible. This study investigates sources of variability that could affect the accuracy of the resorcinol method in identifying phases within the Gigartinaceae. Vegetative disks of Iridaea splendens from different areas of the blade and disks containing reproductive structures all reacted consistently to the resorcinol reagent. The minimum size and testing conditions required to reliably identify phases at the germling stage of I. splendens were determined. Phases of I. splendens cannot be identified if blades are stored in 3% formaldehyde in seawater. Phases of I. splendens, I. lineare, I. heterocarpa, Rhodoglossum californicum and R. affine can be identified reliably at different times of the year. Manipulations of the resorcinol method improved its accuracy in identifying phases of Iridaea cornucopiae and Gigartina exasperata but the high percent of G. exasperata misidentified demonstrates that it cannot be assumed that the current resorcinol method works for all taxa in the Gigartinaceae.     

Ecology and morphological characterization of gametophyte and 'Chantransia' stages of Sirodotia huillensis (Batrachospermales, Rhodophyta) from a stream in central Mexico

The morphology and phenology of Sirodotia huillensis was evaluated seasonally in a central Mexican first‐order calcareous stream. Water temperature was constant (24–25°C) and pH circumneutral to alkaline (6.7–7.9), and calcium and sulfates were the dominant ions. The gametophyte stages were characterized by the presence of a distinctive mucilaginous layer, a marked difference in phycocyanin to phycoerythrin ratio between female and male plants, and the presence of a carpogonia with a large trichogyne (>60 µm). Occasionally three capogonia were observed on a single basal cell. The ‘Chantransia’ stages were morphologically similar to those described for the other members of Batrachospermales. A remarkable observation was the formation of dome‐shaped structures, consisting of prostrate filaments that are related with the development of new gametophytes. Chromosome numbers were n = 4 for fascicle cells, cortical filament cells and dome‐shaped cells, and 2n = 8 for gonimoblast filament cells and ‘Chantransia’ stage filaments. Gametophytes and ‘Chantransia’ stages occurred in fast current velocities (60–170 cm/s) and shaded (33.1–121 µmol photons/m²/s) stream segments. The population fluctuated throughout the study period in terms of percentage cover and frequency: the ‘Chantransia’ stages were most abundant in the rainy season, whereas gametophytic plants had the highest frequency values during the dry season. These results were most likely a result of fluctuations in rainfall and related changes in current velocity. Some characteristics of this population can be viewed as probable adaptations to high current velocities: the mucilaginous layer around plants that reduces drag; potential increase in fertilization by the elongate and plentiful trichogynes and abundant dome‐shaped structures producing several gametophytes.     

Ecological studies of economic red algae. II. Culture studies of Chondrus crispus Stackhouse and Gigartina stellata (Stackhouse) batters

The carpospores of Chondrus crispus Stackhouse and Gigartina stellata (Stackhouse) Batters were grown under a variety of light intensities, temperatures, and salinities. Chondrus exhibited a rapid increase in growth concurrent with increasing intensities up to 440 ft-c and tended to level off above this intensity. Gigartina exhibited a less rapid, but more consistent, increase in cell production coincident with increasing light intensity through 770 ft-c. The growth of both species was accelerated with increasing temperatures to 19 °C. Spores of C. crispus germinated and grew relatively rapidly over a broad range of salinities (15–45‰ at 19°C). Gigartina exhibited a more restricted tolerance to reduced salinity (20 ‰ at 19°C). The local distribution and abundance of both species are correlated with their responses in culture as well as with previous observations on their photosynthesis and respiration.     

Comparative morphology and systematics of Chondrymenia lobata from the Mediterranean Sea and a phylogeny of the Chondrymeniaceae fam. nov. (Rhodophyta) based on rbcL sequence analyses

The Chondrymeniaceae Rodríguez-Prieto, G. Sartoni, S.-M. Lin & Hommersand, fam. nov., is proposed for Chondrymenia lobata. Analyses of rbcL sequences place the new family in a large gigartinalean assemblage that comprises the Cystocloniaceae–Solieriaceae complex. Plants are decumbent and growth takes place by division of multiple apical cells at the margin of the blade. Thalli consist of an outer cortex of subspherical to elongate cortical cells arranged in anticlinal rows, a subcortex of cells cross-linked by lateral arms, and a large central medulla composed of primary medullary filaments intermixed with numerous rhizoidal filaments. Male stages are reported in monoecious individuals. Inactive carpogonial branches consist of a two-celled filament that is directed inwards from the supporting cell. Functional carpogonial branches are oriented outwardly, with the carpogonia and trichogynes pointed towards the thallus surface. After presumed fertilization, the carpogonium fuses with the hypogynous cell and transfers the zygote nucleus. The hypogynous cell, in turn, fuses with the supporting cell which contains many haploid nuclei. The resulting fusion cell functions as an auxiliary cell that cuts off a single gonimoblast initial, which produces the gonimoblast filaments. Gametophytic cells close to the auxiliary cell unite with it to form a placental fusion network of variable size and outline, and a placental fusion cell. Proximal gonimoblast cells fuse with the placental fusion cell, while the distal cells differentiate into branched chains of subspherical carposporangia. The superficial similarity of the outwardly developed osteolate cystocarp is responsible for Kylin's (1956) placement of Chondrymenia in his family Sarcodiaceae; however, the manner in which the placenta is formed is more like that seen in the Cystocloniaceae–Solieriaceae complex.     

PROPOSAL OF THE GRACILARIALES ORD. NOV. (RHODOPHYTA) BASED ON AN ANALYSIS OF THE REPRODUCTIVE DEVELOPMENT OF GRACILARIA VERRUCOSA1

The mode of division of vegetative cells, formation of spermatangial parent cells, initiation of the carpogonial branch apparatus, and formation of tetrasporangial initials are homologous developmental processes that are documented for the first time in the type species of the economically important family Gracilariaceae, Gracilaria verrucosa (Hudson) Papenfuss from the British Isles. G. verrucosa is characterized by a supporting cell of intercalary origin that bears a 2-celled carpogonial branch flanked by two sterile branches, direct fusion of cells of sterile branches onto the carpogonium, formation of an extensive carpogonial fusion cell through the incorporation of additional gametophytic cells prior to gonimoblast initiation, gonimoblast initials produced from fusion cell lobes, schizogenous development of the cytocarp cavity, inner gonimoblast cells producing tubular nutritive cells that fuse with cells of the pericarp or floor of the cystocarp, absence of cytologically modified tissue in the floor of the cystocarp, and carposporangial initials produced in clusters or irregular chains. Spermatangial parent cells are generated in flaments from intercalary cortical cells that line an intercellular space forming a ‘pit’ or ‘conceptacle’. Tetrasporangial initials are transformed from terminal cells derived through division of an outer cortical cell. Tetrasporangia are cruciately divided. The Gracilariaceae is removed from Gigartinales and transferred to the new order Gracilariales. Their closest living relatives appear to be agarophytes belonging to the Gelidiales and Ahnfeltiales.     

Gracilaria corallicola and G. multipartita (Gracilariales,Rhodophyta), two related flattened European species

Two European species of Gracilaria possess flattened blades borne on cylindrical axes, namely, G. multipartita, known primarily from the Atlantic coast, and G. corallicola from the Mediterranean Sea. They are sister species that cluster with G. armata, G. bursa-pastoris and G. longa in rbcL analyses with strong bootstrap support. Blades of G. multipartita taper towards the tips, whereas those of G. corallicolla have broadly rounded tips. Spermatangia of G. corallicola are borne in shallow conceptacles (textorii-type) and data from the literature indicate that the same is true of G. multipartita. Cystocarp morphology is similar, with the gonimoblast filaments initially elongated, narrow and densely filled with cytoplasm, and with tubular nutritive cells issuing initially from lower gonimoblast cells and fusing with cells in the lowermost regions of the outer pericarp. Tetrasporangia are initiated terminally and displaced laterally with the production of side branches from the subterminal cell. The diagnostic characters of the Gracilariaceae are reviewed from a developmental perspective.     

Molecular phylogeny and developmental studies of Apoglossum and Paraglossum (Delesseriaceae,Rhodophyta) with a description of Apoglosseae trib. nov.

Our morphological and molecular studies indicate that species from the southern hemisphere previously placed in Delesseria belong in Paraglossum and that Paraglossum and Apoglossum comprise a separate tribe, the Apoglosseae, S.-W. Lin, Fredericq & Hommersand, trib. nov., within the family Delesseriaceae. From a vegetative perspective the Apoglosseae is readily recognized because some or all fourth-order cell rows are formed on the inner sides of third-order cell rows. All fourth-order cell rows grow adaxially in Apoglossum, whereas both adaxial and abaxial cell rows are present in Paraglossum. Periaxial cells do not divide in Apoglossum, whereas they divide transversely in Paraglossum in the same way as in Delesseria. Major branches are formed mainly from the margins of midribs in the Apoglosseae. The procarp consists of a straight carpogonial branch and two sterile cells, with the second formed on the same side as the first. The carpogonium cuts off two connecting cells in tandem from its apical end, the terminal cell being nonfunctional and the subterminal cell typically fusing with the auxiliary cell. Gonimoblast filaments radiate in all directions from the gonimoblast initials and produce carposporangia terminally in branched chains, with pit connections between the inner gonimoblast cells broadening and enlarging. The auxiliary cell, supporting cell, and sterile cells unite into a fusion cell, which remains small in Apoglossum but incorporates the branched inner gonimoblast filaments and cells in the floor of the cystocarp in Paraglossum. Elongated inner cortical cells seen in mature cystocarps in the Delesserieae are absent in the Apoglosseae. Phylogenetic studies based on rbcL (RuBisCO large subunit gene) sequence analyses strongly support the recognition of the Apoglosseae within the subfamily Delesserioideae of the Delesseriaceae, in agreement with our previous observations based primarily on analyses of large subunit ribosomal DNA (LSU).     

The life history of Ahnfeltiopsis paradoxa (Gigartinales, Rhodophyta) in laboratory culture

The life history of the red alga Ahnfeltiopsis paradoxa (Suringar) Masuda (Phyllophoraceae, Gigartinales) from Japan was completed in laboratory culture. Carpospores isolated from field-collected plants germinated to form circular crusts that were composed of a monostromatic hypothallium consisting of radiating filaments, a polystromatic perithallium consisting of tightly coalescent erect filaments, and hypobasal tissue derived from the hypothallium. The crusts were induced to sporulate by transferring them from short-day to long-day regimes at 15° and 2°C. Each crust produced several nemathecia along 1-4 concentric rings. Intercalary, cruciately or decussately divided tetrasporangia were formed in 4-6 (1-2 at the margin of the nemathecium) successive cells of a single filament of the nemathecia. Tetraspore germlings gave rise to basal discs from which upright axes developed. The upright axes first grew without branches or were sparsely branched and later bore many marginal reproductive proliferations. Procarps and spermatangia were formed in the proliferations on different individuals. Carposporophytes developed on female plants that were co-cultured with male plants. Gonimoblast filaments were formed from an auxiliary cell that fused with a carpogonium. Carposporangia developed from gonimoblast filaments and medullary cells contacted by the gonimoblast filaments. Carpospores were discharged through carpostomes formed in the thickened cortex. Tetraspores were cultured from field-collected crusts of a morphology similar to that of cultured tetrasporophytes. They gave rise to upright gametophytic axes similar in morphology to this species as seen in the field.     

Morphology and molecular relationships of Leptofauchea rhodymenioides (Rhodymeniales,Rhodophyta), a new record for Japan

Leptofauchea rhodymenioides Taylor (Faucheaceae, Rhodymeniales) is reported from Japan for the first time, based on detailed morphological studies and molecular phylogenetic analyses of nuclear‐encoded small subunit ribosomal RNA (SSU rRNA) and plastid‐encoded rbcL gene sequences. This is the first report of male gametophytes and detailed carposporophyte development in the genus Leptofauchea. This species is characterized as follows: (i) flat, membranous, and regularly and dichotomously branched thalli; (ii) the older blades are constricted below the apices; (iii) the cortex is composed of a continuous layer with an irregularly arranged outer layer, and the medulla of two to three incomplete layers; (iv) gametophytes are dioecious; (v) in males, the cortical cells cut off two to three spermatangial mother cells, which produce terminal spermatangia; (vi) in females, the procarp is composed of a three‐celled carpogonial branch and a two‐celled auxiliary cell branch; (vii) upon fertilization, the carpogonium directly contacts the auxiliary cell; (viii) the auxiliary mother cell fuses with vegetative cells, and forms a large trunk‐like fusion cell; (ix) gonimoblast filaments develop outwardly, and transform completely into carposporangia; (x) the carposporophyte is covered with a pericarp with a well‐defined tela arachnoidea; (xi) the mature cystocarp is spherical, has an ostiole, and protrudes from the blade margins; and (xii) the cruciately divided tetrasporangia are formed in nemathecia, produced laterally from paraphyses or terminally on short filaments. Molecular analyses suggest that Leptofauchea forms a strong sister alliance with the genus Webervanbossea. The families Faucheaceae and Lomentariaceae, and the genera Leptofauchea and Webervanbossea are monophyletic, but the latter two genera are not included in the Faucheaceae.     

The morphology and ecology of Nemastoma and Predaea species (Nemastomataceae,Rhodophyta) from Ghana

Two members of the family Nemastomataceae (Gigartinales, Rhodophyta) are described from subtidal habitats in Ghana. Nemastoma confusum sp. nov. is a plant of irregularly lobed, thick gelatinous blades with subacute marginal projections and surface proliferations. It is composed of a lax medulla and submoniliform cortical filaments with prominent intercalary gland cells. Carposporophytes are one to three spherical lobes of carposporangia borne on gonimoblast initials arising directly from auxiliary cells contacted by connecting filaments. A rudimentary involucre is formed around the gonimoblast by elongating vegetative cortical cells borne on the auxiliary cell. The genus Predaea is recorded for the first time from Africa, and P. feldmannii Boerg. is described in morphological detail together with some observations on its ecology in Ghana. Distinctive features of connecting filament formation, nutritive cell production and gonimoblast initiation and development are illustrated and compared to other species of the genus. A second species, P. masonii (Setch. & Gardn.) De Toni fil., is represented by a single specimen in the collections and appears to be distinct from P. feldmannii on cortical and gland cell features.     

AUGOPHYLLUM,A NEW GENUS OF THE DELESSERIACEAE (RHODOPHYTA) BASED ON rbcL SEQUENCE ANALYSIS AND CYSTOCARP DEVELOPMENT1

A new genus, Augophyllum Lin, Fredericq et Hommersand gen. nov. related to Nitophyllum, tribe Nitophylleae, subfam. Nitophylloideae of the Delesseriaceae, is established to contain the type species Augophyllum wysorii Lin, Fredericq et Hommersand sp. nov. from Caribbean Panama; Augophyllum kentingii Lin, Fredericq et Hommersand sp. nov. from Taiwan; Augophyllum marginifructum (R. E. Norris et Wynne) Lin, Fredericq et Hommersand comb. nov. (Myriogramme marginifructa R. E. Norris et Wynne 1987) from South Africa, Tanzania, and the Sultanate of Oman; and Augophyllum delicatum (Millar) Lin, Fredericq et Hommersand comb. nov. (Nitophyllum delicatum Millar 1990 ) from southeastern Australia. Like Nitophyllum, Augophyllum is characterized by a diffuse meristematic region, the absence of macro‐ and microscopic veins, procarps consisting of a supporting cell bearing a slightly curved four‐celled carpogonial branch flanked laterally by a cover cell and a sterile cell, a branched multicellular sterile group after fertilization, absence of cell fusions between gonimoblast cells, and tetrasporangia transformed from multinucleate surface cells. Augophyllum differs from Nitophyllum by the blades becoming polystromatic inside the margins, often with a stipitate cylindrical base, the possession of aggregated discoid plastids neither linked by fine strands nor forming bead‐like branched chains, spermatangia and procarps initiated at the margins of blades, not diffuse, and a cystocarp composed of densely branched gonimoblast filaments borne on a conspicuous persistent auxiliary cell with an enlarged nucleus. Analyses of the rbcL gene support the separation of Augophyllum from Nitophyllum. An investigation of species attributed to Nitophyllum around the world is expected to reveal other taxa referable to Augophyllum.     

THE ATLANTIC SPECIES OF SOLIERIA (GIGARTINALES,RHODOPHYTA): THEIR MORPHOLOGY,DISTRIBUTION AND AFFINITIES1

Solieria chordalis (C. Agardh) J. Agardh and S. tenera (J. Agardh) Wynne et Taylor exhibit multiaxial growth from a cluster of four to eight obconical apical cells. A single periaxial cell is cut off from each axial cell and successive periaxial cells are rotated 120° in a zig-zag pattern along each axial filament. Periaxial cells produce branched, laterally diverging filaments which form the cortex. The medulla is composed of axial cells, elongate cells of lateral filaments, stretched interconnecting cells, and secondary rhizoids. The two species are nonprocarpic. Carpogonial branches are 3-celled, inwardly directed, with a reflexed trichogyne. The auxiliary cell together with associated darkly-staining inner cortical cells form an association, the auxiliary cell complex, that is recognizable prior to diploidization. A single, unbranched, non-septate connecting filament issues from the fertilized carpogonium and fuses with the inner, lateral side of an auxiliary cell. Production of an involucre from surrounding vegetative cells is stimulated and a gonimoblast initial is cut off toward the interior of the thallus which divides to form a compact cluster of gonimoblast cells. A fusion cell is produced through fusion of inner gonimoblast cells with the auxiliary cell that, in turn, fuses progressively with cells of the lateral file bearing the auxiliary cell. Mature cystocarps have terminal carposporangia cut off from gonimoblast cells at the periphery of the fusion cell and are surrounded by an involucre with a distinct ostiole. Tetrasporangia are cut off laterally from surface cortical cells which then cut off one or two additional derivatives toward the outside. A lectotype is designated for Solieria chordalis, but the lectotypification of S. tenera is questioned. We conclude that Solieria is closely related to Rhabdonia and place the Rhabdoniaceae in synonomy with the Solieriaceae.     

Studies of the Liagoraceae (rhodophyta) of Western Australia: Gloiotrichus fractalis gen. et sp. nov. and Ganonema helminthaxis sp. nov.

Two new taxa of Liagoraceae (Nemaliales) are described from Western Australia. Gloiotrichus fractalis gen. et sp. nov. has been collected from 3–20 m depths at the Houtman Abrolhos, Western Australia. Plants are calcified, extremely lubricous, and grow to 17 cm in length. Carpogonial branches are straight, 6 or 7 cells in length, arise from the basal or lower cells of cortical fascicles, and are occasionally compound. Branched sterile filaments of narrow elongate cells arise on the lower cells of the carpogonial branch prior to gonimoblast initiation, at first on the basal cells, then on progressively more distal cells. Following presumed fertilisation the carpogonium divides transversely, with both cells giving rise to gonimoblast filaments. The distal cells of the carpogonial branch then begin to fuse, with fusion progressing proximally until most of the cells of the carpogonial branch are included. As fusion extends, the filaments on the carpogonial branch are reduced to the basal 2 or 3 cells. The gonimoblast is compact and bears terminal carposporangia. Spermatangial clusters arise on subterminal cells of the cortex, eventually displacing the terminal cells. The sequence of pre- and post-fertilisation events occurring in the new genus separates it from all others included in the Liagoraceae, although it appears to have close affinities with the uncalcified genus Nemalion. Ganonema helminthaxis sp. nov. was collected from 12 m depths at Rottnest Island, Western Australia. Plants are uncalcified and mucilaginous, the axes consisting of a few (< 10) primary medullary filaments, each cell of which gives rise to a cortical fascicle at alternate forks of the pseudodichotomies borne on successive medullary cells. Subsidiary (adventitious) filaments and rhizoids comprise the bulk of the thallus. Carpogonial branches are straight, (3-)4(-6) cells in length, arise on the basal 1–4 cells of the cortical fascicles, and are frequently compound. Carposporophytes develop from the upper of two daughter cells formed by a transverse division of the fertilised carpogonium. Ascending and descending sterile filaments girdle the carpogonial branch cells and arise mostly on the supporting cell prior to fertilisation. Ganonema helminthaxis is the first completely non-calcified member of the genus, and its reproductive and vegetative morphology supports the recognition of Ganonema as a genus independent from Liagora. Liagora codii Womersley is a southern Australian species displaying features of Ganonema, to which it is transferred.     

MORPHOLOGY OF PLACENTOPHORA (SOLIERIACEAE,GIGARTINALES: RHODOPHYTA), A NEW GENUS BASED ON SARCODIOTHECA COLENSOI FROM NEW ZEALAND1

The only member of the red algal family Solieriaceae known from New Zealand is the endemic Sarcodiotheca colensoi (Hook. & Harv.) Kylin. This study shows that it differs in several respects from the type S. furcata (Setch. & Gard.) Kylin; thus a new genus Placentophora is created for the New Zealand alga. Although P. colensoi nov. comb. is retained in the Solieriaceae on the basis of vegetative, spermatangial, tetrasporangial, carpogonial-branch and early gonimoblast features, it differs from typical members of that family in its pattern of later carposporophyte development. After a single gonimoblast initial is cut off from the auxiliary cell towards the center of the thallus, further gonimoblasts develop from the initial as ramifying, radiating filaments. These filaments enter an extensive “nutritive-cell” region surrounding the auxiliary cell, form, numerous connections to the “nutritive” cells, and incorporate most of them into a central placenta of interconnected, and variously-fused vegetative and gonimoblast cells. Carpo-sporangia then form in short chains around the periphery of the placenta. The cystocarp lacks both a central fusion cell and a sterile-celled investment, or “Faserhülle.” The distinctive carposporophyte of Placentophora is compared to patterns of gonimoblast development, known in other members of the Solieriaceae.