Stucture and reproduction of Cordylecladia guiryi sp. nov. (Rhodophyta,Rhodymeniales) from the Mediterranean Sea

Abstract

Cordylecladia guiryi sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with C. erecta, the only species of the genus. The species is characterized by the small dimension of its axes which arise single from the basal crust and by its habitat, growing epiphytically on Posidonia oceanica Delile leaves. Tetrasporangial and gametangial plants as well as the development of the carposporophyte have been studied in detail. The carpogonial branch is 4-celled and it is formed on a supporting cell that also bears a 3-celled auxiliary branch. Tetrasporangia are cruciately divided. The reproductive details confirm Sparling's view about the great variation existing in the organization of the procarp in members of this order.     

Morphology,temperature and photoperiodic responses in Audouinella botryocarpa (Harvey) Woelkerling (Acrochaetiaceae,Rhodophyta) from Ireland

Abstract

Audouinella botryocarpa is reported for the first time from the British Isles. On the west and south coasts of Ireland and in the Isle of Man it grows in the intertidal on wave-splashed limpet shells and rock surfaces. Populations examined monthly in Galway Bay formed monosporangia throughout the year and tetrasporangia from December to March and May but no gametangial plants were found. Plants isolated into culture from monospores formed monosporangia at daylengths of 8, 10, 12, 14 and 16 h at 6.5, 8, 10, 11 and 15°C; the same plants formed tetrasporangia at daylengths ≤10 h at 8, 10 and 11°C but not at 6.5 and 15°C. Spores isolated from these plants gave rise to further monosporangial plants that also formed tetrasporangia under inductive conditions. Night-breaks of 1 h in a 16 h night prevented tetrasporangial reproduction and a critical daylength of ～10 h was found at 10°C. British Isles Audouinella botryocarpa typically has 6 rounded or irregularly-shaped chloroplasts per cell, each of which has a single, centrally-placed pyrenoid. The chloroplasts grow together in mature cells, typically giving the appearance of a single plate-like chloroplast with 6 pyrenoids. The implications of these observations for the generic classification of acrochaetioid algae is discussed and it is concluded that chloroplast morphology, number and the presence or absence of pyrenoids may provide the basis for a future generic realignment of acrochaetioid algae.     

Mastophoropsis canaliculata (Harvey in Hooker) gen. et comb. nov. (Corallinaceae,Rhodophyta) in Southern Australia

Mastophoropsis canaliculata (Harvey in Hooker) gen. et comb. nov. (Corallinaceae, Rhodophyta) is restricted to south-eastern Australian waters. It is unique among Corallinaceae in possessing an erect, tenacular, branched, taeniform, non-geniculate thallus which produces multiporate tetrasporangial conceptacles. Based on a detailed morphological and anatomical study, including an examination of the designated lectotype, this taxon is referred to the tribe Phymatolitheae in the subfamily Melobesioideae and its relationships to other non-geniculate Corallinaceae are discussed. A simplified microtechnique procedure involving decalcification with nitric acid, resin embedding and staining serially mounted sections with KMnO₄ also is outlined. X-ray microanalysis of surface tissues indicates that calcification occurs largely as CaCO₃ and that various structures contain substantially differing amounts of Ca.     

中国淡水红藻一个新记录属——托氏藻属

报道了中国淡水红藻一个新记录属——托氏藻属Tuomeya Harvey。标本采于江苏徐州。该属以植物体软骨质, 多层细胞紧密排列组成坚固的皮层, 果胞枝弯曲等特征, 区别于串珠藻科Batrachospermaceae的其他属。除对此种藻类的形态作详细描述外, 还通过rbcL序列比较分析其与北美地区样本的地理差异。该属先前在加拿大、美国和南非有过报道。     

An Investigation of Tetrasporogenesis in the Marine Red Alga Gastroclonium clavatum (Roth) Ardissone (Rhodymeniales)

Gastroclonium clavatum tetrasporogenesis have been studied usinglight and electron microscopy. They are spherical bodies whichdifferentiate early and 50–70 per branch segment havebeen recorded. The developing sporangia expand into the largethallus cavity. The plastids become dispersed evenly throughthe cytoplasm at this stage. Thylakoids become arranged as parallelarrays and sporadically a single peripheral thylakoid enclosesall the others; the matrices contain globules reaching a maximumdiameter of 270 nm. Plastid multiplication occurs through binaryor multiple fission. The starch occurs in bowl-shaped grains.The mitochondria are always rich in cristae and often providedwith small opaque inclusions. The Golgi apparatus is markedby pleomorphic dictyosome features. Dictyosome-mitochondrionassociations are frequent. The different kinds of cytoplasmicinclusion are described. Gastroclonium clavatum, Rhodophyta, tetrasporogenesis, ultrastructure     

Erythropeltidaceen (Bangiophyceae,Rhodophyta) von Helgoland

Ontogenesis and reproduction of the Helgolandian taxa of the Erythropeltidaceae have been studied. In all species monospores are only produced from differentiated sporangia. FilamentousConchocelis-like stages have not been observed. Sexual reproduction was formerly demonstrated in the heteromorphous genusErythrotrichopeltis (Kornmann, 1984). Based on these features a revised classification for the family is presented.Porphyropsis imperfecta, a new species, is a widespread epiphyte in sublittoral habitats.     

Agars from Gelidium rex (Gelidiales,Rhodophyta)

Gelidium rex grows in the rocky intertidal of central Chile. Extraction of vegetative G. rex with water at 95 °C yielded 17.9% of agar with a gel strength value of 590 g cm^–2. The gel strength increased up to 1272 g cm^–2 when the alga was treated with alkali prior to extraction. Cystocarpic and tetrasporic thalli of G. rex were extracted with distilled water at 95 °C, affording soluble polysaccharides in 36.0% and 15.7% yield respectively. Polysaccharides of both life history phases were fractionated by chromatography on DEAE Sephadex. Elution with distilled water gave fractions devoid of sulfate; the fraction from cystocarpic plants contained 45.5% of 3,6-anhydrogalactose whereas the neutral fraction from tetrasporic plants contained 40.0% of 3,6-anhydrogalactose. Further elution with 0.1, 0.4, 0.8 and 1.5 molar aqueous solutions of KCl afforded four fractions for each polysaccharide. Chemical analysis of these fractions showed that the agars from cystocarpic and tetrasporic Gelidium rex are mixtures of related polysaccharides that range from neutral polymers to highly sulfated galactans.     

ThePorphyra species of Helgoland (Bangiales,Rhodophyta)

This revision of sevenPorphyra species of Helgoland was based on a study of the structure of their fertile thalli and the behaviour of their spores. Regarding the reproductive organization the species may be arranged in two groups.P. leucosticta andP. purpureo-violacea are obligate monoecious species. Asexual thalli have never been observed in the field. The other five species are generally dioecious. Isomorphic sexual thalli and asexually propagating ones are mixed in uniform populations. Carpospores originating from sexual fusion develop into the diploid Conchocelis phase. Sporangia of asexual plants, though homologous in formation, produce spores of different kinds: aplanospores that give rise to the vegetative thallus directly (inP. umbilicalis, P. insolita n. sp. andP. ochotensis) and spores that develop into haploid Conchocelis (inP. laciniata and inP. linearis). P. laciniata — formerly considered synonymous withP. purpurea — is an independent species. “In an investigation into the life-history of an alga the aim should be to obtain a series of observations of the development of the thallus from the germinating spore and then of the development of the reproductive organs on the mature thallus. In cases where both sexual and asexual spores are formed the germination of both types of spore should be followed, ...” (Drew, 1954, p. 184)     

Relationship between cover of Chondrus crispus (Gigartinales,Rhodophyta) and Phymatolithon (Corallinales,Rhodophyta) on friable rock substrata

Field observations in sublittoral Prince Edward Island, Canada, indicated that on a friable sandstone substratum Chondrus crispus was more commonly associated with Phymatolithon sp. than with bare rock. Thus, a substantial proportion of the population of Irish moss along the coast of Prince Edward Island occurs on this encrusting coralline. These observation may be explained on the basis of the relative stability of the substratum in contrast to other studies in which sloughing of epithallial cells by species of both Phymatolithon and Lithothamnium has been reported to limit epiphytism by fleshy macrophytes.Issued as NRCC 31426.     

Biosystematics of Gracilaria foliifera (Gigarthales, Rhodophyta)

Strains of Gracilaria foliifera (Forsskål) Børgesen isolated into culture from Ireland (where the species would appear to be introduced), England and the Atlantic coast of France were interfertile. Strains of G. foliifera from Texas and North Carolina, U.S.A. were similarly interfertile but did not cross with the European strains. The North Carolina strain was distinctly flattened in culture and superficially resembled G. foliifera from Europe whereas the Texas strain was terete or slightly flattened. Both of the American strains were interfertile with an isolate of G. tikvahiae McLa-chlan from the type locality of this species in northern Nova Scotia, Canada. It seems likely from these data that G. foliifera is not represented on the coast of North America and that G. tikvahiae is a highly morphologically variable species widely distributed from Nova Scotia south to the Caribbean. Examination of type material of Gracilaria foliifera and G. multipartita (Clemente) Harvey, together with phyto-geographical considerations, suggests that the species known as G. foliifera on eastem Atlantic masts should be known as G. rnultipartita , and that G. foliifera s. str . is probably confined to the Red, Arabian, and Indian Seas.     

Der Lebenszyklus vonPorphyrostromium obscurum (Bangiophyceae,Rhodophyta)

Studies on the sexuality and the heteromorphous life cycle ofErythrotrichia ciliaris provided decisive criteria for the establishment of the genusErythrotrichopeltis (Kornmann, 1984). This genus was transferred by Wynne (1986) toPorphyrostromium Trevisan 1848. In the present studyErythrotrichia obscura, the original species of Berthold's (1882) classical observations on the sexuality of this genus, is incorporated toPorphyrostromium. Previously regarded as synonyms,Porphyrostromium ciliare (Carm. ex Harv.) Wynne andP. obscurum (Berth.) nov. comb. proved to be distinct species, differing both in the filamentous and in the peltoid phases of their life cycle. The relationship betweenP. ciliare andP. boryanum (Montagne) Trevisan, type species of the genus, may only be elucidated by future investigations on the basis of field collected material.      

Kalkbohrende Mikrothalli beiHelminthocladia undScinaia (Nemaliales,Rhodophyta)

Shell-boring microthalli inHelminthocladiaandScinaia(Nemaliales, Rhodophyta). Spores shed from pink mussel shells were shown to develop into branched monosiphonous thalli, their filaments penetrating into shell fragments. Isolates from four single germlings were cultivated. Two of these produced gametophytes ofHelminthocladia andScinaia; the others have so far only reproduced by tetraspores or monospores. Evidently the microthalli of some genera of the Nemaliales — which are, with the exception ofNemalion multifidum, known only from cultures — are shell-inhabiting and have therefore not been found in nature. The adult algae occur mainly on shells and CaCO₃ substrates. Until the beginning of the century,Helminthocladia andScinaia frequently occurred at Helgoland, but they have not been found there for more than 50 years. Their microthalli, however, are still present as shell-boring algae. This study is intended to stimulate similar ones in other genera of the Nemaliales so as to obtain a broader basis for discussion of systematic and phylogenetic relationships.     

Stirtonanthus, a new name for Stirtonia (Leguminosae, tribe Podalyrieae)

The new generic name Stirtonanthus is proposed to replace the illegitimate Stirtonia Van Wyk & Schutte (1994), which proves to be a later homonym of Stirtonia A. L . Smith (1926) and Stirtonia R. Brown (1900).     

Balliella,a new genus of ceramiaceae (Rhodophyta)

Detailed studies of various aspects of the morphology and reproduction ofAntithamnion subcorticatum Itono andAntithamnion crouanioides Itono show that these species are incorrectly referred to as the genusAntithamnion. To include these species, a new genus,Balliella, is proposed. In addition, some other algae possibly referable to this genus are briefly discussed. The genusBalliella is here recognized as a member of the new tribeDelesseriopsieae which is most nearly related to the tribe Antithamnieae in the Ceramiaceae. The tribe Delesseriopsieae is now recognized to include the two genera, i.e.,Delesseriopsis andBalliella.     

Population modelling of Gelidium sesquipedale (Rhodophyta, Gelidiales)

A matrix population model of Gelidium sesquipedale, a commercial agarophyte from the Northeast Atlantic, was developed based on demographic data obtained during two years in a commercial stand of Cape Espichel, Portugal. G. sesquipedale individuals were classified into categories such as life cycle phase, spores, juveniles and adult frond size, because the species vital rates, fecundity, fertility, survival, growth and breakage depend on them. We also exemplify the use of a user-friendly modelling software, Stella, to develop a structured-population model. This is the first time this software has been used to model the demography of seaweed populations. The Stella model developed here behaved very similarly to the matrix model, because of its particular construction, which causes the forcing functions to be discrete rather than continuous. The relative importance of spore recruitment and vegetative growth of new fronds in both population growth and population structure was investigated. Elasticity analysis suggests that vegetative recruitment is the most important demographic parameter controlling population growth together with survival and transitions between juveniles (1–6 cm fronds) and class 1 fronds (6–9 cm fronds). On the other hand, sexual reproduction may, by itself, efficiently control the relative proportion of gametophytes and tetrasporophytes in the population, even though its contribution to recruitment is extremely small. A 40% difference in the growth rates of gametophyte and tetrasporophyte submatrices resulted from natural differences in spore recruitment rates. This revised version was published online in June 2006 with corrections to the Cover Date.     

Practical and descriptive techniques for Gelidium rex (Gelidiales,Rhodophyta) culture

Hydrobiologia - Research on the culture of Gelidium rex was approached from two points of view, growth of thalli from spores and growth from re-attachment. Mollusk shells, which are very easy to...     

Agar polysaccharides from Gracilaria species (Rhodophyta, Gracilariaceae)

Yield, physical and chemical properties of agar from three agarophytes species (Gracilaria gracilis, G. dura and G. bursa-pastoris) were determined. The agar yield from the three species varied significantly (P<0.01). The highest yields of agar (34.8%) and the lowest (30%) were obtained from G. bursa-pastoris and G. gracilis, respectively. Highest gel strength (630+/-15 g cm(-2)) was obtained from agar extracted from G. gracilis and lowest from G. bursa-pastoris (26+/-3.6 g cm(-2)). The values of 3,6-anhydrogalactose were similar for G. gracilis and G. dura and there were no significant differences among the species. The sulfate contents varied significantly (P<0.01) and the higher value was obtained from G. bursa-pastoris. Among the three species, G. gracilis showed superior agar quality than the other two species, hence it can be considered a good potential source for industrial use.     

Simaba orinocensis,an earlier name for Simaba multiflora (Simaroubaceae)

Thomas, Wm. Wayt (New York Botanical Garden, Bronz, NY 10458-9980). Simaba orinocensis, an earlier name for Simaba multiflora (Simaroubaceae). Brittonia 37: 190–191. 1985. Simaba orinocensis has been maintained as a species separate from S. multiflora because Kunth’s illustration showed the flowers to be very different from those of S. multiflora. Examination of the holotype reveals that its flowers do not resemble those illustrated by Kunth but are very similar to those of S. multiflora. Therefore, the two names are considered taxonomic synonyms with S. orinocensis having priority. A complete synonymy is given.