Cryptogamie Algologie

Published by Elsevier
Print ISSN: 0181-1568
The original collection of Aspidophora gaudichaudii Montagne was located in the Herbarium of the Laboratoire de Cryptogamie, Muséum National d'Histoire Naturelle (PC), and examined. An earlier report that the peltate, shield-like structures scattered over the lower surface of the blade surface were merely multicellular peglike rhizoidal attachments and not cystocarps was confirmed. The even earlier described Aglaophyllum peltatum Montagne has been found to be the same as Aspidophora gaudichaudii. Morphological evidence points to the identity of both Aspidophora gaudichaudii and Aglaophyllum peltatum with Cryptopleura corallinarum (Nott) Gardner. Because the name Aglaophyllum peltatum has priority, the binomial Cryptopleura peltata (Montagne) M. J. Wynne comb. nov. is proposed.RésuméLe matériel original de Aspidophora gaudichaudii Montagne, conservé dans les herbiers du laboratoire de cryptogamie, au Muséum national d'histoire naturelle (PC), a été examiné. Une observation ancienne, que les peltates, structures en forme de bouclier réparties sur la surface inférieure de la lame, étaient tout bonnement des organes de fixation rhizoïdaux multicellulaires en forme de pointe et non des cystocarpes a pu être confirmée. Il a aussi pu être observé que Aglaophyllum peltatum Montagne, décrit encore plus antérieurement, est le même taxon que Aspidophora gaudichaudii. L'étude morphologique démontre clairement que Aspidophora gaudichaudii et Aglaophyllum peltatum sont conspécifiques avec Cryptopleura corallinarum (Nott) Gardner. Puisque le nom Aglaophyllum peltatum a priorité, le binôme Cryptopleura peltata (Montagne) M. J. Wynne comb. nov. est proposé.
The freshwater red algal genus Psilosiphon (Batrachospermales) is known from the northern tip of North Island (New Zealand), the central coast of New South Wales (Australia) and southwest Tasmania (Australia). There is little morphological variation among or within collections from these disjunct regions and sexual reproduction has not been convincingly demonstrated. All known locations - five collections (four along one stream reach) from southwest Tasmania, and one collection each from New South Wales and North Island - were sampled for molecular study. Trees based on the rbcL chloroplast gene and the limited ITS1-5.8S rDNA-ITS2 nuclear region show the Tasmanian collections grouped together, with the rbcL data supporting the New Zealand collection as a sister taxon, and the New South Wales collection basal to this clade (the unrooted ITS data are uninformative outside the Tasmanian clade). Because this phylogeny is strongly supported by the rbcL data, and the rbcL base-pair differences between collections from the three regions are large (4.4-7.7%), it is proposed that three genetic races be recognised within Psilosiphon scoparium. Due to the absence of corroborating morphological data and sufficient independent molecular data for complete congruence, these races are not given formal taxonomic recognition. However the phylogeny supports an origin for these genetic races prior to the separation of New Zealand from Gondwana. © 2000 Adac/Éditions scientifiques et médicales Elsevier SAS.
Phylogenetic analyses of 27 brown algae including the type genera of the orders Chordariales, Dictyosiphonales, Ectocarpales sensu stricto, and Scytosiphonales, using partial SSU + LSU combined rDNA sequence data, supports a broadly circumscribed order Ectocarpales. This order is redefined to include taxa possessing an exserted, pedunculated pyrenoid. Previous then taxa were placed in the Ectocarpales sensu stricto, the Chordariales, the Dictyosiphonales, or the Scytosiphonales. Algae either lacking a pyrenoid, and sometimes included in the Ectocarpales (Tilopteridales, Ralfsiales sensu Nakamura), or which possess a non-pedunculated pyrenoid (such as those placed in the recently proposed order Scytothamnales, as well as Asteronema, Asterocladon and Bachelotia), are excluded from the Ectocarpales.RésuméUne analyse phylogénétique de 27 algues brunes comprenant les genres type des Chordariales, Dictyosiphonales, Ectocarpales sensu stricto et Scytosiphonales, a été réalisée à l'aide de séquences partielles, combinées, de la petite et de la grande sous-unités des ADN ribosomaux. Cette analyse soutient le concept d'un ordre des Ectocarpales au sens large plutôt que le maintien des quatre ordres cités ci-dessus. L'ordre des Ectocarpales est redéfini dans cet article comme rassemblant les algues brunes qui possèdent un pyrénoïde pédoncule, exsert, et qui étaient autrefois placées dans les Chordariales. les Dictyosiphonales, les Ectocarpales sensu stricto ou les Seytosiphonales. Les algues, soit dépourvues de pyrénoïdes et parfois placées dans les Ectocarpales (Tilopteridales, Ralfsiales sensu Nakamura), soit possédant un pyrénoïde non pédoncule (comme celles placées récemment dans l'ordre des Scytothamnales, ou bien encore Asteronema, Asterocladon et Bachelotia), en sont exclues.
Giant kelp [Macrocystis pyrifera (Linnaeus) C. Agardh] forests are commonly called a community, but their composition varies among sites and depths. While numerous studies mention this variation and it is the descriptive basis for general models of kelp community structure, it has rarely been quantitatively assessed. We described kelp forest structure among four depths (6, 9, 12, and 15 m) at nine sites along 80 km of the relatively pristine Big Sur coast of California. Density and cover of common organisms were assessed in replicate quadrats at each depth in each site. Macrocystis pyrifera formed a surface canopy at eight sites, and bull kelp, Nereocystis luetkeana (Mertens) Postels & Ruprecht, at one site. The understory kelps Pterygophora californica Ruprecht and Laminaria setchellii P.C. Silva and the bat star Asterina miniata Brandt were the most abundant organisms counted as individuals. Geniculate and nongeniculate coralline algae and encrusting invertebrates had the highest cover. Abundances of giant kelp and the two understory kelps, and sessile invertebrates were significantly different among sites, and differences in sessile invertebrate abundance suggest two general 'types' of kelp forests in the region; one with abundant understory kelps and coralline algae and the other with an understory dominated by sessile invertebrates. Among the eight abundant taxa only the abundance of the two types of coralline algae varied significantly among depths when all sites were combined. Cluster analyses indicated two depth zones within these forests. © 2001 Adac/Éditions scientifiques et médicales Elsevier SAS.
In the monitoring programme of the Italian rivers which enter the Adriatic Sea, a relatively closed and small sea with high pollution risk, the assessment of the water quality of the River Esino, a typical central Apennine watercourse, was carried out. The eutrophication/pollution index (EPI-D) proposed for Italian rivers and based on the sensitivity of the diatoms to organic matter, nutrients and mineralization of the water, with particular reference to chloride, was adopted in this analysis. The good results obtained with respect to the various situations of pollution present at the eighteen stations selected along the river, as well as with regard to other diatom-based indices generally used in Europe, seem to confirm the validity of this index for monitoring Italian watercourses.RésuméDans le cadre du programme de surveillance des fleuves italiens qui se jettent dans la mer Adriatique, une mer relativement fermée et peu profonde à haut risque de pollution, l'évaluation de la qualité biologique du fleuve Esino, un cours d'eau typique de l'Apennin central, a été réalisée. L'analyse a été conduite au moyen de l'indice d'eutrophisation/pollution, ou EPI-D, proposé pour les fleuves de l'Italie et qui se fonde sur la sensibilité des diatomées aux sels nutritifs, à la matière organique et à la minéralisation de l'eau, en particulier les chlorures. Les résultats satisfaisants obtenus par rapport aux différentes situations de pollution rencontrées dans les 18 stations examinées, ainsi que par rapport à d'autres indices diatomiques couramment utilisées en Europe, semblent confirmer à nouveau la validité de cet indice pour la surveillance des fleuves et rivières d'Italie.
In the monitoring programme of the Italian rivers which enter the Adriatic Sea, a relatively closed and small sea with high pollution risk, the assessment of the water quality of the River Esino, a typical central Apennine watercourse, was carried out. The eutrophication/pollution index (EPI-D) proposed for Italian rivers and based on the sensitivity of the diatoms to organic matter, utrients and mineralization of the water, with particular reference to chloride, was adopted in this analysis. The good results obtained with respect to the various situations of pollution present at the eighteen stations selected along the river, as well as with regard to other diatom-based indices generally used in Europe, seem to confirm the validity of this index for monitoring Italian watercourses.
On the progressive disappearance of Laminaria digitata on the coasts of Calvados (France). In comparison with results from 1983-1988, when a cartographic study was made on the distribution of the Laminariales and of Sargassum muticum in Lower Normandy (France), we note, on the Calvados coast, a regression of Laminaria digitata which has almost disappeared on the Grandcamp rocks. On the contrary, the growth of the populations of Sargassum muticum is very spectacular at Grandcamp; in summer, 80 % of the substratum in the lower parts of the intertidal zone and in the subtidal are covered by this species.
A detailed study of vegetative and reproductive phases of several populations of a common species of Ulva from Thau Lagoon (France, Mediterranean Sea) showed that the material is in good agreement with Asiatic Ulva pertusa Kjellman. Since October 1994, the date of its first observation in Thau Lagoon, U. pertusa has developed abundant reproductive populations. It is highly probable that this species was introduced at Thau along with oyster transfers from the Pacific. Ulva pertusa is new to the Mediterranean Sea. Une étude détaillée des stades végétatif et fertile de plusieurs populations d'une espèce d'Ulva commune dans l'étang de Thau (France, Méditerranée) a montré qu'elle appartenait à l'espèce asiatique Ulva pertusa Kjellman. Depuis octobre 1994, date de sa première observation dans l'étang de Thau, U. pertusa a développé des populations importantes et fertiles. L'espèce a probablement été introduite à Thau avec des importations d'huîtres en provenance du Pacifique. Ulva pertusa est une espèce nouvelle pour la Méditerranée.
Two kinds of ordinal names are authorized by the International Code of Botanical Nomenclature (ICBN): descriptive names, to which the principle of typification does not apply; and names based on legitimate generic names, which take as their type the type of the generic name. While it is not mandatory to follow priority when applying names of taxa above the rank of family, it is recommended that priority be followed when choosing among self-typifying names. Valid publication of all names at all ranks requires an accompanying description or a reference to a previously published description. Names of non-fossil algae published on or after 1 January 1958 must be accompanied by a Latin description. Determining which author first validly published a name of a suprageneric taxon and in which publication is often made difficult by the failure of an author to signal a new name and by the use of categories and endings not authorized by the ICBN. A list of validly published names of orders in the Phaeophyceae is presented, comprising 22 self-typifying names and 17 descriptive names. In addition, the name Ralfsiales, although it has not yet been validly published, is included because it is in current use. © 2000 Adac/Éditions scientifiques et médicales Elsevier SAS.
A technique for obtaining cross-sections of diatom frustules which retains the integrity of the frustule without recourse to all ultra-microtome and allows their examination under SEM is described. The technique employs the polishing and etching of resin-embedded material and call he applied to cleaned diatoms from field samples or Cultures. Examples are shown of the types of frustule ultrastructure information that Call he obtained using this technique.
Since the initial western Atlantic collections in the Florida Keys and Bermuda during the mid-1800s, Helminthocladia calvadosii sensu auct. (type locality: Calvados, France) has also been identified from the Caribbean Sea and as far south as northern Brazil. Prior to this study, collections from the eastern and western Atlantic had not been compared using molecular-assisted alpha taxonomy. Recent winter-spring collections of H. calvadosii from Bermuda display an overall habit that is distinct from eastern Atlantic plants of the same species, appearing more similar to H. reyesii (type locality: Canary Islands). Utilizing markers for the mitochondrial COI-5P, we have elucidated the relationships between Bermudian isolates and H. calvadosii from near the type locality, verifying their generic placement within the Liagoraceae and demonstrating their distinctiveness. Using vegetative and reproductive characteristics, we conclude that specimens historically identified as H. calvadosii from Bermuda represent a novel species, and propose Helminthocladia kempii Popolizio, C. W. Schneid. et Chengsupanimit sp. nov. for them.
The current study presents the most detailed multigene phylogenetic assessment of the red algal family Kallymeniaceae to date emphasising the floras of Australia (220 specimens), Europe (19 specimens) and North America (54 specimens). Toward a natural classification and in light of our phylogenetic results, we propose numerous taxonomic changes including the recognition of ten new genera: Austrokallymenia Huisman & G.W.Saunders; Glaphyrymeniopsis Kraft & G.W.Saunders; Huonia G.W.Saunders; Leiomenia Huisman & G.W.Saunders; Metacallophyllis A.Vergés & L.Le Gall; Nothokallymenia A.Vergés & L.Le Gall; Rhipidomenia G.W.Saunders; Thalassiodianthus G.W.Saunders & Kraft; Tytthomenia G.W.Saunders; and Verlaquea L.Le Gall & A.Vergés. The proposals of new genera are accompanied by 16 new combinations of which half are for species from the formerly species-rich genus Kallymenia. Approximately 50 undescribed genetic species were uncovered, of which only ten are now formally named, five of which are type species for new genera: Glaphyrymeniopsis mollis Kraft & G.W.Saunders, Huonia sandersonii G.W.Saunders, Leiomenia lacunata Huisman & G.W.Saunders, Tha lassiodianthus incrassatus G.W.Saunders & Kraft and Tytthomenia barrettii G.W.Saunders. The remaining five are Austrokallymenia rebeccae G.W.Saunders & Kraft, A. roensis Huisman & G.W.Saunders, Leiomenia imbricata Huisman & G.W.Saunders, Meredithia compaginata G.W.Saunders, and Verlaquea fimbriata G.W.Saunders. Also described and illustrated for the first time are reproductive features of the northeastern-Pacific Euthora timburtonii Clarkston & G.W.Saunders, which has been known until now only from molecular studies of vegetative thalli. Despite advances made by our work, the need for considerably more taxonomic investigation in this diverse family is demonstrated, particularly within the presently constituted genus Callophyllis.
Champia insularis C.W.S chneider &G .W.S aunders, sp. nov. 2. Holotype as al iving mat prior to dry-pressing [TRP/CWS 12-32-8]. 3. P. B.-A. no. 1934, as C. parvula, from Harrington Sound, Bermuda (Collins et al., 1913). 4-6. Branching habits with an anastomosed pair (arrowhead) [TRP/CWS 12-174-6]. 7. Apex of ab ranch with descending rhizoidal holdfast (arrowhead) [TRP/CWS 12-174-6]. 8. Apex of branch showing descending medullary filaments and associated gland cells [TRP/CWS 12-174-6]. 9. Axial segments of holotype with tetrasporangia [TRP/CWS 12-32-8]. 10. Clustered cystocarps [TRP/CWS 12-149-14]. Scale bars: 2=1c m, 3=2c m, 4-6 =5 00 µm, 7=2 00 µm, 8=5 0µ m, 9= 100 µm, 10 =3 00 µm.
Using molecular-assisted alpha taxonomy, we have uncovered two new pseudocryptic species of Champia in Bermuda, as well as have demonstrated that the European C. parvula, a name previously applied to historical Bermuda collections, and C. farlowii recently described from southern New England, USA, are not part of the island flora. We present COI-5P and rbcL, as well as morphological, evidence to describe two endemic species for the islands, C. hasselbringii sp. nov. and C. insularis sp. nov. They are similar species with compressed but variable axes and a wealth of overlapping anatomical characteristics. However, the two species are distinguished not only by their genetics, but also by reproductive features that are commonly found in the small prostrate, epiphytic species. It is possible that C. hasselbringii could be the correct name for species reported in warm waters of the western Atlantic as C. compressa or C. vieillardii, species with type localities in South Africa and New Caledonia, respectively.
A new culture strain of Navicula veneta Kützing (Bacillariophyceae) was isolated from brown mats covering thermal muds in the SPA town of Abano Terme, Padova, Italy. The morphology, 18S rDNA and rbcL gene sequences of this strain were analysed. The results do not support an existing taxonomic proposal to lower the taxonomic rank of Navicula veneta to a variety of Navicula cryptocephala Kützing. Therefore, we consider Navicula veneta as a good species in its own right. We also hypothesize that the species Navicula veneta, as defined morphologically, contains a number of cryptic species yet to be discovered and analysed genetically.
The eleven species and one variety of Liagora attributed to the Hawaiian Islands by Butters (1911) are revisited. Most have been or are herein reduced to synonymy, and of the five species that were described as new by Butters, the only species still recognized is Liagora hawaiiana. Published accounts of this species are lacking in some details of structure and reproduction. The present paper includes a detailed description of L. hawaiiana, highlighting several of its distinctive features including a slightly diffuse gonimoblast, presence of a fusion cell, and prominent involucre. In addition, L. hawaiiana is newly reported for Lord Howe Island, Australia. The current taxonomic placements of the remaining species are detailed and Liagora hawaiiana Butters, Liagora intricata Butters [= Yamadaella caenomyce], and Liagora maxima Butters [= L. albicans] are lectotypified.
Two new genera, Belonastrum and Synedrella, were erected by Round and Maidana (2001) to accommodate Synedra berolinensis and Synedra parasitica, respectively. Neither genus was characterized by scanning electron microscopy data (SEM), with both of the transfers based primarily on the ecology of the taxa, namely, the planktonic habit of S. berolinensis and the epiphytic nature of S. parasitica. Based on both SEM and detailed comparative analyses of specimens found in North American samples, the two transfers above are refuted. The combination Staurosirella berolinensis, proposed by Buktiyarova (1995), is recommended for Synedra berolinensis. Synedra parasitica and its variety subconstricta are transferred to the genus Pseudostaurosira sensu Williams & Round (1987).
Strict consensus tree of four equally parsimonious trees obtained using the first data set (partial 28S + complete rbcL for 30 species). Numbers indicate bootstrap proportions obtained for MP, followed by bootstrap proportions obtained for NJ and ML methods. Numbers associated with the letter 'd' correspond to decay indices. Branch supports are shown only when bootstrap proportions are over 75 and decay index values over 5. Scale is indicated below the tree. Tree length = 2698 steps, C.I. = 0.441, R.I. = 0.546. (*) = no order name available yet.  
Tree obtained using the second data set (Complete 28S + complete rbcL for 11 species). Numbers indicate bootstrap proportions obtained for MP, followed by bootstrap proportions obtained for NJ and ML methods. Numbers associated with the letter 'd' correspond to decay indices. Branch supports are shown only when bootstrap proportions are over 75 and decay index values over 5. Scale is indicated below the tree. Tree length = 2295 steps, C.I. = 0.6771, R.I. = 0.4429.  
The position of the brown algal genus Microzonia, currently placed in the Cutleriales, was investigated using two different genes: the plastid-encoded rbcL gene and the nuclear-encoded rDNA 28S gene. All our analyses show that Microzonia is the sister taxon of Syringoderma and is not related to the cutlerialean genera Cutleria and Zanardinia. This result is consistent with morphological characters. It is thus proposed to exclude Microzonia from the Cutleriales and to place it in the Syringodermatales. Within the Phaeophyceae, the Syringoderma-Microzonia branch diverges after Choristocarpus and members of the Dictyotales and the Sphacelariales, as the sister taxon of a clade comprising all other orders. The extreme basal position of Choristocarpus is confirmed with both rbcL and 28S genes, contrary to previous reports by other authors.
The marine red alga Dudresnaya abbottiae Afonso-Carrillo et Tabares sp. nov. from the Canary Islands is described. The new species has no single unique feature, but differs from the other Dudresnaya species by a distinctive combination of attributes. Gametophytes are radially branched with terete, nonannulate young branches, crystalline inclusions are lacking in axial cells, outer cortical cells are cylindrical, and rhizoidal filaments cut off from proximal cells of the cortical filaments reach 20 μm in diameter, regularly giving rise to terminal adventitious cortical fascicles. Spermatangial mother cells occur in paniculate clusters on outer cortical cells. Carpogonial and auxiliary-cell filaments lack a thick mucilage coat, generative auxiliary cells are distinguishable from adjacent cells before contact with a connecting filament, cystocarps are loosely constructed, and carposporangia completely surround the auxiliary-cell filament. The most closely related species to Dudresnaya abbottiae appear to be D. babbittiana Abbott et McDermid from the North Central Pacific, D. capricornica Robins et Kraft from Australia and the Arabian Sea, D. kuroshioensis Kajimura from Japan and D. canariensis Tabares, Afonso-Carrillo, Sansón et Reyes from the Canary Islands. Although all these species show important similarities in overall habit and shape of outer cortical cells, the arrangement of spermatangial mother cells and the morphology of rhizoids, generative auxiliary cells and cystocarps distinguish them. A synoptic key to the nineteen species currently included in the genus Dudresnaya is given.
A new species of brown algae, Taonia abbottiana D.S. Littler et M.M. Littler, is described from the tropical western Atlantic. To date, this is the only member of the genus reported from the region. Taonia abbottiana differs from other species of the genus in having (1) sporangia raised above the surface layer on a stalk composed of two cells, and (2) in addition having a surface cortical layer of differentiated cells that are smaller than those of the medullary layers. Taonia abbottiana has often been confused with Stypopodium zonale, but the two differ anatomically in the development of cells directly behind the growing margin and, when living at similar depths, T. abbottiana consistently has light colored concentric lines, while S. zonale has dark concentric lines.
The island of Hawai'i, showing the two sampling locations: Puako and Leleiwi. The prevailing northeasterly trade winds are indicated by arrows.
Number of algal taxa found within each quadrat along one transect at Leleiwi in July 2002.
In the tropics, algal turfs are a key marine community, floristically and ecologically, yet the turf structure and its spatial and temporal variation have seldom been quantitatively assessed. We compared species composition and abundance of turf algae on two shallow subtidal reefs (< 2 m deep) on the island of Hawai'i from September 2000 to July 2002. Of the 102 species of marine algae identified in the algal turf community, 17 belonged to the Chlorophyta, 9 to the Phaeophyta, and 76 to the Rhodophyta. Red algae dominated the turfs at both sites. Species richness, species diversity, and evenness varied between sites and among sampling dates, perhaps due to differences in substratum, precipitation and wave exposure. The most abundant turf species (Ceramium macilentum J. Agardh, Pterocladiella caerulescens (Kützing) Santelices et Hommersand, Hypnea spinella (C. Agardh) Kützing, Coelothrix irregularis (Harvey) Børgesen, Amansia glomerata C. Agardh and Laurencia brachydados Pilger) showed very patchy spatial distributions and variable seasonal abundances. 38 new records for the island of Hawai'i were documented, many of which were common. Although growth form rather than dominant or diagnostic species defines the algal turf community, identification and monitoring of individual species, which have different reproductive and physiological characteristics, are essential to understanding the ecology of the turf.
Probably in 1993 or early 1994, an Asiatic Chondrus, C. giganteus forma flabellatus, was accidentally introduced in the Mediterranean sea where the genus was hitherto unknown. In September 1995, this alga was common on hard substrates along the north coast of Thau lagoon (Herault, France). The Mediterranean specimens are described. The implications of this acclimatization in Thau lagoon and the possible spread of this Chondrus elsewhere in Europe are discussed.
This paper reports the results of experiments on Zn accumulation in two species of green algae: Chara globularis and Chara hispida. The results of laboratory and field experiments show a rapid accumulation of Zn by charophytes and demonstrate that with the exception of precipitation with calcite, an adsorption phase occurs in Zn accumulation. Both species may be important in Zn circulation in lakes.
SEM. 15-22. Achnanthidium kranzii. Specimens from a population of the streamlet Breschterbaach in Pratz, 23.03.1995. 15. RV, outside. 16. RV, inside. 17. RV, outside tilted. 18. RV, inside tilted. 19. AV, outside. 20. AV, inside. 21. AV, outside tilted. 22. AV, inside tilted. 23-32. Achnanthidium minutissimum. Specimens from different populations of Luxembourg, mainly of the river Ernz Blanche near Hessemillen, 27.09.2002. 23. RV, outside. 24. RV, inside. 25. RV, outside tilted. 26. RV, inside tilted. 27. AV, outside. 28. AV, inside. 29. AV, outside tilted. 30. AV, inside tilted. 31. Frustule, strongly tilted. 32. Frustule, tilted. Scale bars = 1 µm. 
SEM. 33-36. Achnanthidium pyrenaicum. Specimens from a population of the streamlet Rollingenbaach in Rollingen, 26.05.2002. 33. RV, outside. 34. RV, inside. 35. AV, outside slightly tilted. 36. AV, inside. 37-42. Achnanthidium subatomus. Specimens from a population of the streamlet Stool in Brandenbourg, 19.07.1995. 37, 38. RV, inside. 39. RV, outside tilted. 40. AV, outside. 41. AV, outside slightly tilted. 42. AV, inside. 43, 44. Psammothidium bioretii. Specimens from a population of the streamlet Breschterbaach in Pratz, 23.03.1995. 43. RV, tilted outside. 44. RV, inside. Scale bars = 1 µm. 
SEM. 45-52. Psammothidium daonense. Specimens from a population of the streamlet Breschterbaach in Pratz, 23.03.1995. 45. RV, outside. 46. RV, inside. 47. RV, outside tilted. 48. RV, inside tilted. 49. AV, outside. 50. AV, inside. 51, 52. AV, outside tilted. 53-59. Psammothidium lauenburgianum. Specimens from a population of the streamlet Gander in Aspelt, 24.10.96. 53. RV, outside. 54. RV, inside. 55. RV, inside tilted. 56. AV, outside. 57. AV, inside. 58. AV, inside slightly tilted. 59. AV, outside tilted. Scale bars = 1 µm. 
SEM. 60-62. Psammothidium helveticum. Specimens from a population of the streamlet Millebaach in Bigelbach, 25.07.1995. 60. RV, outside. 61. RV, outside tilted. 62. AV, outside slightly tilted. 63-65. Psammothidium subatomoides. Specimens from a population of the streamlet Millebaach in Bigelbach, 25.07.1995. 63. RV, inside. 64. RV, outside. 65. AV, outside and RV behind, inside. Scale bars = 1 µm. 
The diagnostic characteristics of the genera Achnanthidium and Psammothidium, the latter genus recently separated from other species of Achnanthes sensu lato, of the family Achnanthidiaceae D.G. Mann have been evaluated on the basis of a morphological study of eleven common species found in rivers and streams of Luxembourg. In light of these observations - supplemented by a literature review - it is concluded that the two genera cannot be unambiguously defined on the basis of morphological criteria. Furthermore, no ontogenetic or phylogenetic studies support any of the discriminating characteristics. On the basis of these results, Achnanthes bioretii, A. daonensis, A. austriaca var. helvetica, A. lauenburgiana and Navicula subatomoides have been transferred to Achnanthidium.
Map of the Gredos Range in Spain (A) and Cimera Lake (B). Cimera Lake bathymetry (C), with the sampling point near the deepest area of the lake. (A) modified from Wikimedia Commons and (B) modified from Open Cycle Maps. 
Psammothidium toroi sp. nov., LM, valve view.T ype material from Cimera Lake, Spain. Size diminution series of whole frustules photographed at different foci to show the raphe and the rapheless valves (the images of the same frustule are paired with a " = " symbol). Scale bar =1 0µ m. 
A population of an unknown Psammothidium species (Bacillariophyta, Achnanthidiaceae) was found in core sediments collected from Cimera Lake, an oligotrophic, undisturbed mountain lake in Central Spain (Gredos mountain range). The morphology and ultrastructure of this taxon is hereby documented in detail by means of light (LM) and scanning electron (SEM) micrographs. Morphologically, the closest taxon is P. levanderi, and the type of this species is analyzed here to provide a differential diagnosis. A comparison with other similar small Psammothidium species with an elliptic outline show that the combination of features exhibited by this taxon is unique and it is thus described here as Psammothidium toroi sp. nov.
Three rare Psammothidium species were found in recently surveyed lakes of Northeastern Siberia, Russia. One of these species found in lakes of the Kolyma Lowland, is new for science and is formally described here as Psammothidium onufrii sp. nov. It is morphologically similar to the brackish-water species Achnanthes punctulata, but it lacks a central area on rapheless valve and possesses a large central area on the raphe valve. Psammothidium onufrii is characteristic for tundra thermokarst lakes with moderate mineral content. Psammothidium sacculum previously reported from a few subarctic and arctic locations was found in several lakes of the Kolyma Lowland and of the Magadan District. The frustule ultrastructure of this species is documented for the first time here. The third species, known as Achnanthes obliqua (W. Gregory) Hustedt and transferred here to Psammothidium, is a morphologically distinct and relatively rare diatom occasionally reported from northern regions of Eurasia and Western North America. In Northeastern Siberia it was found in sediments of relatively large shallow lakes with low to moderate mineral content. Detailed morphological characterization of the three Psammothidium species will facilitate their detection in environmental surveys and their use in paleoenvironmental reconstructions.
Fourteen culture isolates of freshwater acrochaetioid algae from distinct regions around the world were analysed, including the reddish species Audouinella hermannii, the dubious blue-greenish species A. pygmaea, and "Chantransia" stages from distinct taxonomic origins in the Batrachospermales sensu lato (Batrachospermaceae, Lemaneaceae and Thoreaceae). Four isolates (two 'Chantransia' stages and two species of Audouinella, A. hermannii and A. pygmaea) were tested under experimental conditions of temperature (10-25°C), irradiance (65 and 300 μmol photons m-2 s-1) and photoperiod (16:8 h and 8:16 h light/dark cycles). Plant colour is proposed as the only vegetative character that can be unequivocally applied to distinguish Audouinella from 'Chantransia', blue-greenish representing "Chantransia" stages and reddish applying to true Audouinella species (also forming reproductive structures other than monosporangia, e.g. tetrasporangia). Some isolates of A. pygmaea were proven to be unequivocally 'Chantransia" stages owing either to production of juvenile gametophytes or to derivation from carpospores. No association of the morphology of A. pygmaea was found with any particular species, thus it should be regarded as a complex involving many species of the Batrachospermales sensu lato, as is also the case with A. macrospora. We therefore recommend that all blue-greenish acrochaetioid algae in freshwater habitats be considered as "Chantransia" stages of members of the Batrachospermales, and that the informal descriptors "pygmaea" and "macrospora" be used to distinguish the two discernable morphologies. Induction of gametophytes occurred under much wider conditions than previously reported, reinforcing the conclusion that requirements are probably species-specific. Although phenotypic plasticity was in evidence, with temperature, irradiance and photoperiod affecting morphology, no alga showed variation outside the limits based on traditional taxonomic studies. No overall trend was observed for vegetative or reproductive characters in response to temperature, irradiance and photoperiod for all the algae tested, only for specific algae or characters. Effects of temperature and irradiance on morphological characters were more evident, as well as strong interactions between these variables, whereas few differences were generally found in response to photoperiod and irradiance.
Two species of acrochaetioid algae (Rhodophyta) are reported from the Canary Islands for the first time. Both Colaconema ophioglossum comb. nov., previously known from North Carolina and Puerto Rico in the Western Atlantic [as Audouinella ophioglossa Schneider and Acrochaetium ophioglossum (Schneider) Ballantine et Aponte], and Liagorophila endophytica Yamada, cited from several localities in the Pacific Ocean and with a single report from the Caribbean coast of Colombia, constitute new records for the eastern Atlantic Ocean. Colaconema ophioglossum was found growing epi-endophytically between the cortical fascicles of the recently described Canarian endemic Dudresnaya multiramosa Afonso-Carrillo, Sansón et Reyes, which constitutes a new host for this species. Its vegetative cells contain a single lobate parietal chloroplast with a single pyrenoid, a feature exclusive of Colaconema, and consequently the species is transferred to this genus. Liagorophila endophytica was discovered in the outer cortex of Liagora canariensis Børgesen. Data concerning geographical distribution and observations on vegetative and reproductive morphology, especially the development of the carposporophyte, are presented for the two species. In C. ophioglossum, the fertilized carpogonium divides transversely and gonimoblasts are monopodially branched. In L. endophytica the fertilized carpogonium divides longitudinally and the gonimoblasts are radially produced by successive longitudinal cells divisions. This distinctive type of gonimoblast development is regarded as a taxonomically significant feature, and suggests retention of Liagorophila as a separate genus. Conflicting reports of plastid morphology do not allow confident ordinal placement of Liagorophila and the genus is regarded as of uncertain affinity, but allied to the Acrochaetiales or Colaconematales.
The effects of strontium on growth, peroxidation and antioxidative enzymes have been investigated in Dicrateria inornata. The marine microalga grew at all treatment concentrations of strontium, but samples exposed to 512 and 2048 mg strontium l-1 were inhibited by 15.9% and 51.0%, respectively, compared to controls. Among the responses to added strontium, accumulation of malondialdehyde increased significantly at 2048 mg strontium l-1 and was 1.23 fold higher than in controls, and protein content increased at low external concentrations but decreased above 128 mg l-1. In the case of antioxidant enzyme activities, SOD, CAT and GPX activities increased by 85.7, 19.8 and 74.4%, respectively, at 2048 mg strontium l-1 compared to the control. The GSH content increased by 5.2% at 512 mg l-1 and by almost 100% at 2048 mg l-1 strontium compared to controls.
The shallow water canopy-forming alga Ericaria brachycarpa (J.Agardh) Molinari-Novoa & Guiry shows higher photosynthetic efficiency (), maximum photosynthetic rates (Pmax), light at compensation (Ic) and dark respiration (Rd) in individuals collected at the lower depth limit of distribution of the species (20 m) than at shallower depths (2 and 10 m). Photosynthesis at saturation light levels (Psat) does not change in crossed transplants from 3 to 20 and from 20 to 3 m neither after 11 or 90 days. However, production at low light levels (Pb) increased in transplants from 3 to 20 m and decreased in transplants from 20 to 3 m after 90 days. Photosynthesis, both at high and low light levels increased from June to September. Seasonality explained most of the variance (70%) in the values of Psat, whilst transplantation explained 47% of the variance for Pb and Rd. Thus, E. brachycarpa is able to adapt its photosynthetic performances across its depth distribution limits and easily cope with sudden variations in the light environment associated or not with seasonality.
A renewed interest in investigating the relationships existing between body size and environmental variables is pervading ecological studies. Phytoplankton has a long tradition as model system in studies of community ecology and several research concepts were developed using these organisms. In this paper we try to review the relevance of analyzing the morphological features of phytoplankton in ecology. Starting with a brief account of allometric relationships existing in phytoplankton, we i) examine the physical context in which phytoplankton grow, and ii) highlight the role of their size in nutrient uptake, and that of their shape in light harvesting. Moreover, the way in which the morphology of phytoplankton organisms cope with the hydrodynamical conditions of a given water-body are considered. In addition, we also included a paragraph on the role of grazing in moulding the size and the shape structure of phytoplankton assemblages. An account on the main research currents about the role of morphology in the definition of morpho-functional traits of phytoplankton is offered. All these approaches, which can be viewed as complementary of taxonomy, both molecular and "traditional", are promising tools to better understand the functioning of aquatic ecosystems and may offer a vast array of new perspectives in the field of aquatic ecology and phytoplankton research as well as a simplified tool to perform water quality monitoring.
Lectotype of Gymnogongrus ligulatus Harvey ex Kützing (MEL 504575), reproduced with permission from the National Herbarium of Victoria (MEL), Royal Botanic Gardens Melbourne. 
In the cited article, we proposed the new combination Yonagunia ligulata (Harvey ex Kutzing) Manghisi, M. Morabito, De Clerck & Le Gall. In this note, we add the lectotypification of its basyonym, Gymnogongrus ligulatus Harvey ex Kutzing.
Diatoms coming from 140 ponds ("mares") from two regions of France the Calcareous plateau of the Beauce in the north and the sand and clay region of Orléans and Sologne in the south were analyzed for the influence of regional geology, land use and growth support. Both permanent ponds and ephemeral ponds were included in the analyses. Multi-response permutation procedure illustrated the differences and similarities between the two regions, the 13 different classes of pond type and different substrates. The analyses demonstrated why certain types should be regrouped into one large class, with six pond types retained. Most of the substrates categories showed no significant differences but one category, Sphagnum (peat moss) was different from all the others while mud and living roots also differed from many of the other categories. Canonical correspondence analyses of both regions together and then each region separately using only the permanent pond data resulted in different environmental factors explaining species ordination. For the two regions combined three essential factors were determined; pH, log conductivity, and pond surface area. The Beauce calcareous plateau was influenced by pH and K while the sand and clay region of Orléans and Sologne were influenced by log conductivity, and SiO2 on axis 1-2.
Problems associated with the contamination of distinct diatom communities by live or dead frustules (valves) from adjacent communities are discussed. The importance of the recognition and discrete sampling of the numerous microhabitats in both freshwater and marine systems is stressed. Special comments are made concerning the complexity of the epilithic flora in rivers and the 'metaphyton' associated particularly with the epiphyton.
Top-cited authors
Luigi Piazzi
  • Università degli Studi di Sassari
Francesco Cinelli
  • Università di Pisa
David Balata
  • Tenuta San Beda
Line Le Gall
  • Muséum National d'Histoire Naturelle
Marc Verlaque
  • French National Centre for Scientific Research