Effects of nitrate and phosphate availabilities on growth, photosynthesis and pigment and protein contents in colour strains of Hypnea musciformis (Wulfen in Jacqu.) J.V. Lamour. (Gigartinales, Rhodophyta)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of Hypnea musciformis (Rhodophyta)

The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype) collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 mu mol photons m(-2) s(-1)) but, with further increase in irradiance (from 40 to 120 mu mol photons m(-2) s(-1)), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed in temperatures of 20-25 degrees C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins. Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher photosynthetic efficiency (alpha), and lower saturation parameter (I-k) and compensation irradiance (I-c) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting pigments in red algae.

THE FAMILY COMPSOPOGONACEAE (RHODOPHYTA) IN BRAZIL

A taxonomic revision of the family Compsopogonaceae in Brazil was carried out, resulting in the recognition of a single genus (Compsopogon) with two species (C. coeruleus and C. leptoclados). For both species the following information was provided: a) nomenclatural type; b) type locality; c) description (with illustrations); d) diagnostic features; e) world distribution; f) distribution in Brazil (with map); g) habitat, associated species and seasonality; h) remarks, including discussion of taxonomic and/or nomenclatural problems and comparison with previous reports based on Brazilian and foreign material. Currently accepted diagnostic criteria for genera and species within Compsopogonaceae are critically analysed. The circumscription of Compsopogon and Compsopogonopsis are evaluated and the single genus Compsopogon is recognized in the family.

Phylogenetic relationship of Sirodotia species (Batrachospermales, Rhodophyta) in North and South America

Sequence data from the RUBISCO large subunit (rbcL) plastid gene and nuclear small-subunit ribosomal DNA (SSU rDNA) were examined for five samples of Sirodotia delicatula from southeastern Brazil. Data from six North American samples previously identified as S. huillensis and S. suecica were also included in the analysis. Molecular data supported the continued recognition of these three species as separate entities, although one of the North American collections was misidentified. These results were shown to be congruent with morphology, chromosome number and geographic distribution. S. delicatula is more closely related to S. huillensis, both occurring in tropical-subtropical regions, than either to S. suecica with a temperate-boreal distribution. There was little rbcL variation within S. delicatula from Brazil and Costa Rica (the latter a collection previously identified as S. huillensis), with the six samples sequenced diverging from each other by 0-8 bp (0-0.67%). SSU rDNA data set did not provide sufficient resolution to infer phylogenetic relationships among the species of this group due to the low rates of variation (5 bp). Sirodotia was a well-supported clade (100% bootstrap or 1.00 a posteriori probability) based on rbcL sequences. Thus, the results confirm that Sirodotia is a monophyletic group within the Batrachospermales and we continue to recognize it at the generic level. The species S. delicatula, S. huillensis and S. suecica are morphologically and genetically distinct.

THE SECTION SIRODOTIA OF BATRACHOSPERMUM (RHODOPHYTA, BATRACHOSPERMACEAE) IN BRAZIL

The taxonomy, distribution and ecology of Section Sirodotia of Batrachospermum in Brazil is studied. Only one species, B. delicatulum (SKUJA) NECCHI & ENTWISLE, was recognized. This species presents a wide range of morphological features, occurs in a number of distinct habitats and environmental conditions and is widely distributed in Brazil. A full account of the species taxonomy is given and the synonyMy of B. ateleium comb. nov. SKUJA is confirmed. Two growth forms (dense and open) were found in the Brazilian specimens, but they were not treated as different taxa because a continuous range was observed between them. Two morphological features were proposed for species delineation: early development of gonimoblast and presence of specialized spermatangial branches. Three distinct groups of Sirodotia species can be recognized on the basis of these criterions: B. delicatulum (gonimoblast initial arises from a semiglobular protuberance of the carpogonium), B. suecicalum KYLIN (gonimoblast initial arises from the non-protuberant side of the carpogonium) and B. segawae KUMANO and B. yutakae KUMANO (with specialized spermatangial branches).

DISTRIBUTION AND SEASONAL DYNAMICS OF RHODOPHYTA IN THE PRETO RIVER BASIN, SOUTHEASTERN BRAZIL

Distribution and seasonal dynamics of freshwater Rhodophyta were investigated in the Preto River basin, located in northwestern São Paulo State, southeastern Brazil. Twenty-two sites were sampled, six monthly during one year, four bimonthly during two years, and 12 twice (hot-rainy and cool-dry seasons) during the study period (May 1989 through March 1991). Red algal representatives were found in 19 sites (86.4%). Four species occurred in the basin with varying frequencies: Batrachospermum delicatulum (54.5%), Compsopogon coeruleus (36.4%), B. bicudoi (13.6%) and B. virgatum (4.5%). In addition, 'Chantransia' stage of the batrachospermalean species was found in 17 sites (77.3%). B. bicudoi, B. virgatum and C. coeruleus occurred only in large stream segments (greater-than-or-equal-to 3-order), generally in the main river, whereas B. delicatulum was more frequent in small streams (less-than-or-equal-to 3-order). The stream variables most closely related to the species distribution in the basin were specific conductance, pH and oxygen. B. bicudoi and B. delicatulum showed a marked seasonality: gametophytes were observed from late fall to early spring, while the 'Chantransia' stage generally occurred throughout the year. C. coeruleus was observed throughout the year in most sites, but the populations were generally more abundant from late fall to early spring. The combination of lower temperature and reduced turbidity resulting in increased illumination to the benthic algae during the dry winter months promotes the gametophytic growth of the batrachospermalean species, whereas current velocity was found to be the most influential stream variable for C. coeruleus. The persistance of the 'Chantransia' stage throughout the year as well as its tolerance to wider environmental conditions are key factors in the efficiency of the batrachospermalean life history strategy in lotic ecosystems.

SYSTEMATICS OF FRESH-WATER AUDOUINELLA (ACROCHAETIACEAE, RHODOPHYTA) IN NORTH-AMERICA .1. THE REDDISH SPECIES

Multivariate morphometrics and image analysis were used to determine the number of well-distinguished infrageneric taxa of reddish freshwater Audouinella in North America. Three distinct groupings were differentiated from 83 populations collected from Alaska and Labrador in the north to central Mexico and Jamaica in the south. These groupings were statistically related to seven type specimens. The following species were recognized: A. eugenea (SKUJA) JAO, A. hermannii (ROTH) DUBY [syn.: A. violacea (KUTZ.) HAMEL and its varieties, alpina (KUTZ.) RAB., dalmatica (KUTZ.) RAB., expansa (WOOD) SMITH, and hercynica (KUTZ.) KUTZ.] and A. tenella (SKUJA) PAPENFUSS. These species are separated based on dimensions of vegetative cells and monosporangia. A. tenella is found only in California, A. eugenea in warm, alkaline and high-ion waters of the tropical rainforest and desert-chaparral, while A. hermannii occurs widely from the boreal to south temperate and in waters with relatively low temperatures and ion content.

A new species and expanded distributions of freshwater Audouinella (Acrochaetiaceae, Rhodophyta) from Central Mexico and south-eastern Brazil

Eighteen collections of red-coloured Audouinella from Central Mexico and southeastern Brazil detected three species. The most common species, A. eugenea, is characterized by macroscopic thalli, the erect system consisting of filaments with cylindrical cells, undifferentiated into proximal and distal parts, and relatively large monosporangia (greater than or equal to 12.0 mum long). Spermatangia. and possible propagules were observed in some Mexican populations. This is the third Audouinella species observed to have gametangia and the first member of the Acrochaetiales with putative propagules. The second species, from Central Mexico, was characterized by the following features: macroscopic thalli, the erect system differentiated into proximal parts with cylindrical cells, unbranched or rarely branched, and distal parts with barrel-shaped cells, abundantly branched to form dense fascicles, with alternate or dichotomous branching, some at right-angles to the axis, and relatively large monosporangia (greater than or equal to 12.0 mum long). The morphologically distinct proximal and distal portions of the erect system, the latter forming dense fascicles, was a consistent character so far unknown in Audouinella; thus, we propose a new species, A. huastecana sp. nov. The third species is a microscopic epiphyte, A. meiospora, with a well-developed prostrate system composed of creeping and loosely aggregated filaments, and a short homogeneous erect system (less than or equal to 15 cells) of filaments with cylindrical or barrel-shaped cells and small monosporangia (less than or equal to 13.0 mum long). A. eugenea and A. meiospora are characterized for the first time from the Southern and Northern Hemispheres, respectively, both occurring mostly in areas of tropical or subtropical rainforests. A. meiospora is reported from new macroalgal hosts. A. eugenea and A. huastecana tended to occur in warm, alkaline waters with a high ion content that were moderate to fast flowing, whereas A. meiospora was not associated with particular habitats.

A REAPPRAISAL OF GENERIC AND SUBGENERIC CLASSIFICATION IN THE BATRACHOSPERMACEAE (RHODOPHYTA)

The generic and subgeneric classification of the family Batrachospermaceae (Rhodophyta) has long been recognized as ambiguous and often inconsistent. One of the prime features used to delineate sections of Batrachospermum, trichogyne shape, is variable even within given species. However, characters associated with the carposporophyte and the carpogonial branch, as well as carpogonial symmetry, are practical and consistent taxonomic criteria. These features have been used to redefine sectional delineation in Batrachospermum. Based on phylogenetic reasoning and practicality, it is proposed that the three genera Nothocladus, Sirodotia and Tuomeya be reduced to sectional level within Batrachospermum. The genus Batrachospermum would thus become the sole member of the Batrachospermaceae and would include two subgenera, Batrachospermum and Acarposporophytum, the former with nine clearly defined sections (Aristata, Batrachospermum, Contorta, Hybrida, Nothocladus (Skuja) stat. nov., Sirodotia (Kylin) stat. nov., Tuomeya (Harvey) stat. nov., Turficola and Viridia). As a result, the following nomenclatural changes are proposed: Batrachospermum lindaueri (Skuja) comb. nov., B. nodosum (Skuja) comb. nov., B. delicatulum (Skuja) comb. nov., B. fennicum (Skuja) comb. nov., B. suecicum (Kylin) comb. nov. and B. americanum (Kutzing) comb. nov.

Audouinella macrospora (Acrochaetiaceae, Rhodophyta) is the Chantransia stage of Batrachospermum (Batrachospermaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microhabitat and plant structure of Compsopogon coeruleus (Compsopogonaceae, Rhodophyta) populations in streams from São Paulo State, southeastern Brazil

Microhabitat distribution was investigated in three populations of C. coeruleus to determine the distributional patterns and their controlling factors, as well as morphometric adaptations to varying conditions on a scale of a few centimetres. Morphometric variations and their relations with physical variables (current velocity, irradiance, depth and type of substratum) revealed some particular characteristics for each population and indicate particular adaptations. However, some trends were clear: 1) larger plants (length and/or diameter) produced a higher quantity of monosporangia in the three populations; 2) plant length and diameter were positively correlated in two populations; 3) plant diameter was positively correlated with current velocity in two populations; 4) higher percent cover was associated with substrata composed of macrophytes in two populations. C. coeruleus occurred under relatively wide microhabitat conditions and had high niche width values, suggesting a tolerance to considerable variation in physical variables. These characteristics contribute to the species' wide distribution in Brazilian streams, both spatial (at distinct scales) and seasonal. (C) ADAC / Elsevier, Paris.