Showing papers in "Phycologia in 1986"
TL;DR: The substitution of Hepes for Tris allows a defined seawater medium to be used as a fixative vehicle for the first time.
Abstract: N-2-hydroxyethylpiperazine-N-2′-ethanesulfonic acid (Hepes) has been tested as an alternative to tris-(hydroxymethyl)aminoethane (Tris) for hydrogen-ion buffering of algal cultures. Hepes satisfactorily buffered both freshwater and artificial seawater media and has been used successfully to grow 25 species of microalgae from five classes. Electron microscopic fixations of Tetraselmis striata Butcher (Prasinophyceae) and Amphidinium rhyncocephalum Anissimowa (Dinophyceae) buffered by Hepes have given far superior ultrastructural preservation than fixations buffered by Tris. The substitution of Hepes for Tris allows a defined seawater medium to be used as a fixative vehicle for the first time.
229 citations
TL;DR: Proteomonas sulcata gen. et sp.
Abstract: Proteomonas sulcata gen. et sp. nov. (Cryptophyceae) is described from Australian waters. It has an unusual life history involving two morphologically distinct and alternating forms that are identified as haploid and diploid stages. Both the haplomorph and the diplomorph reproduce by simple cell division, and each is capable of producing the other cell type. The two forms can be distinguished by size, periplast structure, configuration of the flagellar apparatus, and the quantity of nuclear DNA. Details of the life history and morphology of this cryptomonad are presented and discussed with reference to cryptomonad taxonomy.
77 citations
TL;DR: In this article, the authors reexamined this coralline flora by comparing field and museum collections with type material in order to revise the taxonomy to conform with current concepts and provide new, species specific, ecological data.
Abstract: Encrusting coralline algae are a major component of the rocky intertidal and shallow subtidal zones of the boreal northeastern Pacific (the region from northern California to southeast Alaska). We reexamined this coralline flora by comparing field and museum collections with type material in order to revise the taxonomy to conform with current concepts and to provide new, species specific, ecological data. Of the eight species previously recognized for this region, only Pseudolithophyllum neofarlowii, and Lithothamnion (formerly Lithothamnium) phymatodeum were correctly placed as to genus. Phymatolithon muricatum and Mesophyllum whidbeyense are referred here to the genus Pseudolithophyllum. Lithothamnion pacificum is merged into L. phymatodeum and Lithophyllum lichenare is merged into Pseudolithophyllum muricatum. Lithothamnion californicum and Hydrolithon decipiens were shown not to occur in the study area. Plants in this study area formerly identified as H. decipiens were originally and correct...
65 citations
TL;DR: The taxonomic relationships of Ulva californica, U. angusta and U. scagelii were evaluated through morphological studies of field and herbarium specimens, and through culture studies, showing ecological, morphological and cytological similarities but differ in size, habit and distributions.
Abstract: The taxonomic relationships of Ulva californica, U. angusta and U. scagelii were evaluated through morphological studies of field and herbarium specimens, and through culture studies. These species show ecological, morphological and cytological similarities but differ in size, habit and distributions. Morphological studies of specimens from Alaska to southern California indicate a gradation in size and habit with latitude. Thalli also vary predictably with wave energy and season. Laboratory studies indicate that isolates identified as U. californica and U. scagelii are capable of hybridizing and have similar developmental patterns. Both species can produce germination tubes and extensive basal rhizoidal discs. Development of the basal disc is influenced by temperature and other culture conditions. When grown at temperatures between 15° and 20°C the basal disc gives rise to numerous secondary thalli, resulting in a tufted habit. This compares well with field observations. Based upon morphological,...
45 citations
TL;DR: A new species of Lessonia, L. trabeculata Villouta et Santelices is described from Chile, which extends at least from Antofagasta to near Puerto Montt along temperate Pacific South America.
Abstract: A new species of Lessonia, L. trabeculata Villouta et Santelices is described from Chile. The two most important characters segregating this new species from all other species of Lessonia are the presence of trabeculae in the cortical lacunae of blades and stipes, and holdfast morphology, which is massive and irregularly shaped. This species extends at least from Antofagasta (c. 23°S) to near Puerto Montt (c. 40°S) along temperate Pacific South America. The plants grow to 2.5 m long often forming extensive kelp beds at depths ranging between 0.5 and 20 m.
42 citations
TL;DR: All populations from Lake Baikal were characterized by a common developmental trajectory, different from populations from other localities, and all populations except those from Karluk Lake and Lake Superior could be distinguished from one another with a high degree of confidence on the basis of shape alone.
Abstract: We investigated populations of the diatom genus Didymosphenia from Lake Baikal, two localities in China, in Lake Karluk, Alaska, and in Lake Superior using quantitative shape analysis. Four different taxa were distinguished in the Lake Baikal material, two belonging to recognized species, and two of uncertain affinities. All populations from Lake Baikal were characterized by a common developmental trajectory, different from populations from other localities. All populations except those from Karluk Lake and Lake Superior could be distinguished from one another with a high degree of confidence on the basis of shape alone.
41 citations
TL;DR: The resulting data suggest that Mesophyllum can be distinguished from other genera of the Melobesioideae by the occurrence of a core of filaments where the cells are arranged in a coaxial manner.
Abstract: Neotype specimens for Mesophyllum lichenoides (Ellis) Lemoine, the type species of Mesophyllum Lemoine (Corallinaceae, Rhodophyta) have been designated and critically examined, and the concept and status of the genus have been reassessed. All efforts to rediscover the original Ellis collection, which was sold at auction in 1791, have failed, and consequently a neotype was chosen from recently collected specimens from Cornwall (England). A detailed morphological and anatomical account of the neotype plants is provided, and the resulting data suggest that Mesophyllum can be distinguished from other genera of the Melobesioideae by the occurrence of a core of filaments where the cells are arranged in a coaxial manner. Nomenclatural and taxonomic data relating to Mesophyllum and its type species are presented along with relevant historical data and a brief consideration of the relationships of M. lichenoides to other species of Mesophyllum and to Millepora agariciformis Pallas.
40 citations
TL;DR: A new species of the biflagellate euglenoid Eutreptiella is described from Danish and American waters and features of particular interest include details of the nuclear endosome, the arrangement of the flagellar hairs and the presence of a system of mucocyst-like bodies in the posterior end.
Abstract: A new species of the biflagellate euglenoid Eutreptiella is described from Danish and American waters. Although somewhat similar to E. braarudii, known from Norway, the new species differs in havin...
40 citations
TL;DR: P Phenetic and cladistic analyses of the character state data suggest that the major genera of the Achnanthaceae may form distinct evolutionary lineages, which have each converged on the reduced raphe condition.
Abstract: A review of previously published hypotheses concerning phylogenetic relationships in the diatom family Achnanthaceae is presented. Data for characters such as valve ultrastructure, chloroplast number and morphology, and sexual reproduction for the genera Cocconeis, Achnanthes and Rhoicosphenia and their purported biraphid allies Mastogloia and Gomphonema are reviewed. Phenetic and cladistic analyses of the character state data suggest that the major genera of the Achnanthaceae may form distinct evolutionary lineages, which have each converged on the reduced raphe condition. Cocconeis appears to be more similar to Mastogloia and to represent one lineage, while Rhoicosphenia appears to be most similar to Gomphonema and to represent a second lineage. The genus Achnanthes may represent at least one additional independent lineage. Taxonomic implications of the present report are discussed.
37 citations
TL;DR: The pigment analysis by high performance liquid chromatography shows that the light-harvesting chlorophyll–protein contains a complex pattern of pigments, which is unusual for green algae.
Abstract: Micromonas sp. (Plymouth no. 27 marine) was grown in batch cultures at low irradiance (3.4 W/m2). The light-harvesting complex was isolated by polyacrylamide gel electrophoresis and characterized by its absorption spectrum, molecular weight, thermostability and composition of photosynthetic pigments. The absorption spectrum of the isolated protein complex indicates that, besides chlorophyll a and b, another green pigment is bound to the protein. The apparent molecular weight of the light-harvesting protein of Micromonas was found to be comparable to other green and yellow–green complexes. The stability of the isolated protein to detergents and high temperature is apparently higher than in other groups of eucaryotic algae. The pigment analysis by high performance liquid chromatography shows that the light-harvesting chlorophyll–protein contains a complex pattern of pigments, which is unusual for green algae. The absorption spectra of the third green pigment and its retention time in reverse phase ...
36 citations
TL;DR: A rou tine fiat embedding method for electron microscopy of microorganisms allowing selection and precisely orientated sectioning of single cells by light micros copy is proposed.
Abstract: CAIOLA M.G. 1975. A light and electron microscopic study of blue-green algae growing in the coralloid roots of Encephalartos altensteinii and in culture. Phycologia 14: 25-33. ERASMUS D.A. 1978. Electron Probe Microanalysis in Biology. Chapman and Hall, London. GRIFFITHS D.J., THINH L.-V. & WINSOR H. 1984. Crystals and paracrystalline inclusions of Prochloron (Prochlorophyta) symbiotic with the ascidian Tri didemnum cyclops (Didemnidae). Botanica marina 27: 1 17-128. HOROBIN R.W. 1982. Histochemistry. Gustav Fi scher, Stuttgart, New York. JENSEN T.E. 1978. Paracrystalline inclusions in var ious isolates of the blue-green bacteria Nostoc and Anabaena. Cytobios 22: 179-190. JENSEN T.E. 1984. Cyanobacterial cell inclusions of irregular occurrence: systematic and evolutionary implications. Cytobios 39: 35-62. JENSEN T.E. & BOWEN C.C. 1970. Cytology of blue green algae. II. Unusual inclusions in the cytoplasm. Cytologia 35: 132-152. MONNERON A. 1966. Utilisation de la pronase en cytochimie ultrastructurale. J. Microscopie 5: 583596. MONNERON A. & BERNHARD B. 1966. Action de certaines enzymes sur des tissus inclus en epon. J. Mi croscopie 5: 697-714. PICKETT-HEAPS J.D., TIPPIT D.H. & ANDREOZZI J.A. 1978. Cell division in the pennate diatom Pinnu laria. I. Early stages in mitosis. Bioi. Cellulaire 33: 71-78. PRINGSHEIM E.G. 1963. Farblose Algen. Gustav Fischer, Stuttgart. PuESCHEL CM. & PARTHASARATHY M.V. 1984. X-ray microanalysis of phytoferritin in Constantinea (Cryptonemiales, Rhodophyta). Phycologia 23: 465469. REYMOND O.L. & PICKETT-HEAPS J.D. 1983. A rou tine fiat embedding method for electron microscopy of microorganisms allowing selection and precisely orientated sectioning of single cells by light micros copy. J. Microscopy 130: 79-84. SPECTOR D.L. & JENSEN T.E. 1977. Fine structure of Leptogium cyanescens and its cultured phycobiont Nostoc commune. The Bryologist 80: 445-460. THORSCH J. & ESAU K. 1983. Nuclear crystalloids in sieve elements of Boraginaceae: a protein digestion study. J. Cell Sci. 64: 37-47. VOLKER H., SCHWEISFURTH R. & HIRSCH P. 1977. Morphology and ultrastructure of Crenothrix poly spora Cohn. J. Bacteriol. 131: 306-313.
TL;DR: The development from zoospore to adult stage was followed in detail with the result that no more than three morphological groups can be discerned, which are designated as Stigeoclonium helveticum, S. tenue, and S. farctum.
Abstract: The prostrate thallus of Stigeoclonium was studied under defined culture conditions. The development from zoospore to adult stage was followed in detail with the result that no more than three morphological groups (or species) can be discerned. The three groups are designated as Stigeoclonium helveticum, S. tenue, and S. farctum. Considerable intra- and intergenotypic variation exists, especially in the erect system of Stigeoclonium helveticum and in the prostrate system of S. tenue. The prostrate system of Stigeoclonium farctum is not always a closed pseudoparenchymatous disc, but may form an open star-like ‘variabile’ habit.
TL;DR: Two new generic names are proposed: Kansodinium gen. nov. for Diplopsalis ambiguum (Thompson) Bourrelly, and Durinskia gen.NoV.
Abstract: Two new generic names are proposed: Kansodinium gen nov for Diplopsalis ambiguum (Thompson) Bourrelly, and Durinskia gen nov for Peridinium balticum (Levander) Lemmermann The nomenclatural history of each taxon is discussed, and features observed from natural collections are used to further characterize the new genera
TL;DR: The peculiar displacement of the basal bodies to one another and to the cell is discussed as are similarities and variations in the flagellar apparatus of the few other described dinoflagellates.
Abstract: The three-dimensional structure of the flagellar apparatus has been determined in the small dinoflagellate Heterocapsa pygmaea Loeblich, Schmidt & Sherley. Some peculiar features of the flagellar apparatus include the displacement of the basal bodies toward the cell's right, the presence of a longitudinal microtubular root that extends to the cell's left-posterior, a small fibrous connective that links the transverse basal body with a collared pit of the anterior pusule, a layered connective that links the proximal end of each basal body, and a transverse striated fibrous root that extends from the transverse basal body to the cell's left. Two striated collars are also present as well as a striated fibrous connective between the microtubular root and the striated fibrous root. The peculiar displacement of the basal bodies to one another and to the cell is discussed as are similarities and variations in the flagellar apparatus of the few other described dinoflagellates. A diagrammatic reconstructi...
TL;DR: Seven species of the genus Scinaia (Nemaliales, Galaxauraceae) are reported from Australia, including three new species and three previously recorded species, with the exception of S. aborealis and S. proliferata which produce numerous sterile branches on their hypogynous cells rather than the two sterile branches uniformly present in other members of the species.
Abstract: Seven species of the genus Scinaia (Nemaliales, Galaxauraceae) are reported from Australia, including three new species (S. aborealis, S. howensis, S. proliferata), one new record (S. caribaea, previously known only from Haiti) and three previously recorded species [S. australis, S. moniliformis, S. tsingalensis (as S. moretonensis)]. Habits, vegetative morphology and reproductive development have been examined in all seven species and compared with taxa of Scinaia from elsewhere. As a result, S. indica (previously known from India) and S. moretonensis are reduced to synonymy with S. moniliformis and S. tsingalensis, respectively. The reproductive development of the seven species is typical of the genus, with the exception of S. aborealis and S. proliferata which produce numerous sterile branches on their hypogynous cells rather than the two sterile branches (one one-celled, one two-celled) uniformly present in other members of the genus. As these two species retain this apparently primitive condition (numerous sterile branches on the hypogynous cell are also found in Gloiophloea, the probable progenitor of Scinaia), it is postulated that they are closely related to the forerunners of the genus. Scinaia proliferata produces cortical utricles of mixed sizes in a manner similar to S. forcellata (the type species of the genus) and probably arose early in the evolutionary line that produced that species and all of those previously included in Pseudoscinaia and Pseudogloiophloea. Scinaia aborealis produces uniformly sized cortical utricles and probably occupies a similar position in the evolutionary line that produced the remaining species of Scinaia.
TL;DR: Age distribution, age specific attrition, and age specific fecundity of Pterygophora californica Ruprecht were studied at three sites in Barkley Sound, British Columbia, Canada.
Abstract: Age distribution, age specific attrition, and age specific fecundity of Pterygophora californica Ruprecht were studied at three sites in Barkley Sound, British Columbia, Canada. These variables were then used in a Leslie Matrix model to test their predictive value. The age structure was similar at all three sites: most plants were of intermediate age with few very young ( 8 years) ones. For each of the populations studied the dominant age class changed unpredictably from year to year, due to changes in the age specific survivorship. Approximately 108–1010 spores are produced per plant per year. The survivorship data, when used in the model, are not a good predictor of age structure due to their year to year variation. When survival and fecundity were kept constant in the model, lambda (the finite rate of increase) was more responsive to changes in survival than to fecundity.
TL;DR: The type species is reported from tropical eastern Australia, as are the two new species G. dotyi and G. larkumii, and a third new species, G. womersleyi, is described from the cool-temperate southwest of Australia.
Abstract: Until now, the genus Gibsmithia has been monotypic, with the type species (G. hawaiiensis Doty) recorded only from Hawaii and French Polynesia. In this paper, the type species is reported from tropical eastern Australia, as are the two new species G. dotyi and G. larkumii. A third new species, G. womersleyi, is described from the cool-temperate southwest of Australia. All are characterized by lengthy (6–16 celled) carpogonial filaments bearing sterile laterals on their lower cells; auxiliary-cell filaments terminated by sterile cells shaped like normal vegetative cortical cells; globular cystocarps subtended by a lax involucre of filaments produced prior to gonimoblast initiation by lower cells of the auxiliary-cell filament; and decussately cruciate tetrasporangia borne on isomorphic tetrasporophytes. Plants of all but G. larkumii consist of cartilaginous, presumably perennial stalks bearing gelatinous, annual blades. Gibsmithia larkumii is distinguished by its lack of stalks and the non-cluster...
TL;DR: Investigations carried out in neritic waters of the north east of the Golfe de Gascogne revealed a phytoplanktonic species of centric diatom new among the algal microflora of the French Atlantic coasts: Coscinodiscus wailesii Gran & Angst.
Abstract: Investigations carried out in neritic waters of the north east of the Golfe de Gascogne revealed a phytoplanktonic species of centric diatom new among the algal microflora of the French Atlantic coasts: Coscinodiscus wailesii Gran & Angst. Information on the occurrence of this species obtained from planktonologists in several parts of the world confirm some of its ecological characteristics and bring distributional data up to date. Two hypotheses are proposed with respect to the occurrence of this species along the European coast.
TL;DR: Frustule morphology and its variability were studied by means of light and electron microscopy, both transmission and scanning and the following ought to be mentioned: shape and size of the valves, position of the axial area and number of the labiate processes.
Abstract: Presently the only valid species of Pseudohimantidium is P. pacificum, described by Hustedt & Krasske, from the northern marine Chilean water masses. Frustule morphology and its variability were studied by means of light and electron microscopy, both transmission and scanning. Among the least stable characteristics the following ought to be mentioned: shape and size of the valves, position of the axial area and number of the labiate processes. Detailed information is presented about the structure of the cingulum. The epicingulum may have up to eight bands; these bands cannot be differentiated into valvocopula and copulae. The specimens studied were collected along the coast of Chile between 18° and 38°S, either by netting or isolated from copepods of the genus Corycaeus Dana.
TL;DR: Four new species of Rhipiliopsis from eastern and western Australia and one new species from the Philippines are described and compared anatomically with the type of the genus, R. carolyniae, and characterized by corticated or spinous mono- or multisiphonous stalks, polystromatic blades, and siphons.
Abstract: Four new species of Rhipiliopsis from eastern (R. gracilis, R. howensis, R. millarii) and western (R. multiplex) Australia and one new species (R. carolyniae) from the Philippines are described and compared anatomically with the type of the genus, R. peltata (J. Agardh) A. & E.S. Gepp. Rhipiliopsis echinocaulos (Cribb) Farghaly comb. nov. from eastern Australia has also been studied. All are characterized by corticated or spinous mono- or multisiphonous stalks, polystromatic blades, and siphons which either cohere directly at scattered localized sites or form lateral attachment processes. Distinguishing features include habit, number of siphon layers composing the blade, presence or lack ofblade differentiation into distinct medullary and cortical regions, siphon diameter and shape, degree of constriction above siphon dichotomies, presence (and distribution) or absence of spines on blade siphons, and stalk anatomy. Rhipiliopsis multiplex is unique in producing branching erect axes with tiers of p...
TL;DR: The irregularly lobed shape of H. asymmetrica, the mode of formation of spermatangia in discrete, raised sori, and the small size of cystocarps serve to distinguish this species from previ...
Abstract: A new species of Halymenia (Halymeniaceae, Gigartinales) is described from the Bay of Naples, Italy. H. asymmetrica is characterized by a planar thallus, up to 50 cm wide, growing from a short cuneate stipe. The blade is lobed and shows an essentially entire margin. One of the lobes is usually more expanded, giving an asymmetrical appearance to the thallus. Tetrasporangial and gametangial plants have been studied in detail. Tetrasporangia are cruciately divided. Carpogonial and auxiliary ampullae arise from inner cortical cells; cystocarps are surrounded by an involucre originated from the ampullary filaments. Spermatangial sori are raised on the surface of the thallus. Comparison is made with other species of the genus, particularly those with foliose thalli that have been described from the Mediterranean Sea. The irregularly lobed shape of H. asymmetrica, the mode of formation of spermatangia in discrete, raised sori, and the small size of cystocarps serve to distinguish this species from previ...
TL;DR: Gracilaria tenuifrons is distinguished from the several other species of subgenus Gracilariella by various aspects of its morphology and vegetative anatomy, size of tetra-sporangia and carposporangio and the structure of its pericarp and spermatangial sorus.
Abstract: Gracilaria tenuifrons sp. nov., a species with superficial spermatangia (subgenus Gracilariella Yamamoto), is described from Alagoas, in northeastern Brazil, where it inhabits protected, turbid waters at depths of approximately 0.5–1 m. Additional specimens are known from the West Indies, from Cuba to Tobago. A slender, terete and branched species, G. tenuifrons has been misidentified as G. sjoestedtii Kylin [= G. lemaneiformis (Bory) Weber-van Bosse], and a detailed comparison of the two species is provided. Gracilaria tenuifrons is distinguished from the several other species of subgenus Gracilariella by various aspects of its morphology and vegetative anatomy, size of tetra-sporangia and carposporangia and the structure of its pericarp and spermatangial sorus.
TL;DR: Sexual reproduction in Gonium sociale (Dujardin) Warming was studied in detail at the light microscope level under controlled laboratory conditions, with particular regard to conjugation between gametes and zygote germination.
Abstract: Sexual reproduction in Gonium sociale (Dujardin) Warming was studied in detail at the light microscope level under controlled laboratory conditions, with particular regard to conjugation between gametes and zygote germination. One of the two conjugating gametes bore a slender cytoplasmic protrusion (unilateral mating papilla) at the base of the flagella and the other did not. Plasmogamy was initiated by the union between the tip of the protrusion of the former gamete and the anterior region of the latter. Four biflagellate gone cells were liberated separately from a germinating zygote. These two attributes in G. sociale are essentially different from those of G. pectorale Muller as well as of the other genera of Volvocaceae and Astrephomenaceae.
TL;DR: The ultrastructural features described support the suggestion that there is considerable genetic diversity within what has previously been regarded as a single species, Symbiodinium microadriaticum.
Abstract: Aspects of the in situ ultrastructure of the dinoflagellate symbiont of a Zoanthus species from the Great Barrier Reef region are described. The in situ symbiont resembles what has previously been described as the gymnodinioid form of Symbiodinium microadriaticum, especially in the general morphology and fine structure of the pyrenoid. The Zoanthus sp. symbiont stands apart from other gymnodinioid symbionts in having stacked chloroplast lamellae. It has regularly arranged sub-amphiesmal microtubules, flagellar basal bodies and masses of electron dense material distributed in the amphiesma. The ultrastructural features described support the suggestion that there is considerable genetic diversity within what has previously been regarded as a single species, Symbiodinium microadriaticum.
TL;DR: Computerized image analysis shows that trichogyne shape, when used in conjunction with its size and localization, is a taxonomic feature for this and other species in the genus.
Abstract: A new species, Batrachospermum carpocontortum, is described from northwest Washington state, USA. The combination of long, straight carpogonial branches, one or two large external carposporophytes and sessile trichogynes with protrusions and bends is unique amongst the current subgeneric sections employed. Hence a new section, Carpocontorta, is established. Other characteristics of the new species include dioecious plants, olive-green to brown color, 3–8 cm filament lengths, barrel-shaped, contiguous, lateral whorls, abundant secondary branches, few hair cells and dichotomous or trichotomous fascicle branching. Computerized image analysis shows that trichogyne shape, when used in conjunction with its size and localization, is a taxonomic feature for this and other species in the genus.
TL;DR: The morphogenetic responses to temperature and photoperiod of plants from Nova Scotia, Canada belonging to the Scytosiphon lomentaria complex were evaluated and formed uprights in response to short daylength.
Abstract: The morphogenetic responses to temperature and photoperiod of plants from Nova Scotia, Canada belonging to the Scytosiphon lomentaria complex were evaluated. Formation of erect thalli by clonal isolates of S. lomentaria var. complanatus was controlled by temperature, and independent of daylength. All plants formed uprights at 0°C (14 :10 h), 5°C (14 : 10 h) and 10°C (16 :8 h, 12 :12 h and 8 : 16 h); only few did so at 15°C (16 : 8 h and 12 : 12 h) and none at 20°C (16 : 8 h and 12 : 12 h). In contrast, uprights of S. lomentaria var. lomentaria were formed in response to short daylength (10°C).
TL;DR: Hymenocladiopsis crustigena as mentioned in this paper is a new genus and species of marine Rhodophyceae, which is described from the Antarctic Peninsula and assigned to the Rhodymeniaceae.
Abstract: A new genus and species of marine Rhodophyceae, Hymenocladiopsis crustigena, is described from the Antarctic Peninsula and assigned to the Rhodymeniaceae. Thalli consist of large, pinnately branched blades borne on an extensive crust. The cortex of the blade is composed of one or two layers of cells. The medulla, in which intercellular spaces or cavities are present, is composed of large and small cells, some of which bear spherical gland cells. Reproductive structures are produced on the main blade or on pinnae. The carpogonial branch is a cluster of three cells that fuse following fertilization. Cystocarps, which lack a tela arachnoidea, are large and protuberant. Tetrasporangia are tetrahedrally divided. Hymenocladiopsis crustigena occurs subtidally along the Antarctic Peninsula from Marguerite Bay to the South Orkney Is. It differs from Hymenocladia by having tetrasporangia that are terminal rather than intercalary and gland cells that are medullary rather than cortical. It appears to be rela...
TL;DR: A new species of kelp, Macrocystis laevis, is described from Marion Island in the southern Indian Ocean with characteristic blades that are fleshy and perfectly smooth–never corrugated or rugose as with other species in the genus.
Abstract: A new species of kelp, Macrocystis laevis, is described from Marion Island in the southern Indian Ocean. This species has characteristic blades that are fleshy and perfectly smooth–never corrugated or rugose as with other species in the genus. The vesiculate blades forming the kelp canopy are also commonly sporophylls. These features are considered in relation to the criteria currently used to separate the species of Macrocystis. The possibility that the Marion Island species is an allopatric species originating from a population of Macrocystis in the Falkland Islands is considered.