Michael D. Guiry

HOW MANY SPECIES OF ALGAE ARE THERE

Algae have been estimated to include anything from 30,000 to more than 1 million species. An attempt is made here to arrive at a more accurate estimate using species numbers in phyla and classes included in the on‐line taxonomic database AlgaeBase (http://www.algaebase.org). Despite uncertainties regarding what organisms should be included as algae and what a species is in the context of the various algal phyla and classes, a conservative approach results in an estimate of 72,500 algal species, names for 44,000 of which have probably been published, and 33,248 names have been processed by AlgaeBase to date (June 2012). Some published estimates of diatom numbers are of over 200,000 species, which would result in four to five diatom species for every other algal species. Concern is expressed at the decline and potential extinction of taxonomists worldwide capable of improving and completing the necessary systematic studies.

Composition and spatial variability of terrestrial algal assemblages occurring at the bases of urban walls in Europe

Abstract Communities of terrestrial green algae occurring at the bases of old, weathered walls are widespread in temperate urban areas, but have been virtually unstudied. In spring and summer 2002 we examined collections from a number of cities in northern Europe (Galway, Dublin, Manchester, Durham, Copenhagen) and southern Europe (Oviedo, León, Bordeaux, Marseilles, Pisa) and from several localities in western Ireland. Seventeen taxa of green and blue-green algae were found. Filamentous green algae were the most common forms and the assemblages could be subdivided into two different types: a Prasiolales assemblage (in which the dominant forms are Rosenvingiella sp. and Prasiola calophylla) and a Klebsormidium assemblage (dominated by species of Klebsormidium). The patterns of distribution of the most abundant species showed marked differences between the cities sampled, but no significant effect of latitude. The vegetation of each of the cities examined was generally assignable either to the Prasiolales assemblage (Galway, Dublin, Durham, Oviedo and León) or the Klebsormidium assemblage (Manchester, Copenhagen, Bordeaux, Marseilles and Pisa). For western Ireland, no significant variation was detected in the assemblages at different distances from the Atlantic. Climatic factors operating at a scale of hundreds of kilometres are considered the most important in determining the relative distribution of these assemblages. The Prasiolales assemblage is primarily associated with the rainy and cool Atlantic regions of Europe, whereas the Klebsormidium assemblage is dominant in continental and Mediterranean areas. The composition of these assemblages shows extremely limited variation on small spatial scales and no significant variation is detectable between different areas of the same city or town for any of the most common species. Physiological attributes of the Prasiolales and Klebsormidium in relation to different climatic regimes are considered to play a fundamental role in the distributional patterns of these algae.

New perspectives in the taxonomy of the Gigartinaceae (Gigartinales, Rhodophyta)

A revised description of the Gigartinaceae is provided, together with a key and short diagnosis of each genus and a list of the species examined. New combinations have been proposed where appropriate. Distinguishing cystocarp and tetrasporangial characters useful for separating genera are illustrated, and the distribution of the genera is shown on a world map.

Antimycobacterial, antiprotozoal and cytotoxic potential of twenty-one brown algae (phaeophyceae) from British and Irish waters

In the continuation of our research on seaweeds, crude extracts of 21 brown algae collected from the south coast of England and the west coast of Ireland were screened for in vitro trypanocidal, leishmanicidal and antimycobacterial activities. Mammalian stages of a small set of parasitic protozoa; i.e. Trypanosoma brucei rhodesiense, T. cruzi and Leishmania donovani, and the tubercle bacillus Mycobacterium tuberculosis were used as test organisms. The extracts were also evaluated for selectivity by testing on a mammalian cell line (L6 cells). Only four extracts were moderately active against T. cruzi, whereas all algal extracts showed significant activity against T. brucei rhodesiense, with Halidrys siliquosa and Bifurcaria bifurcata (Sargassaceae) being the most potent (IC50 values 1.2 and 1.9 μg/mL). All algal extracts also displayed leishmanicidal activity, with H. siliquosa and B. bifurcata again being the most active (IC50s 6.4 and 8.6 μg/mL). When tested against M. tuberculosis, only the B. bifurcata extract was found to have some antitubercular potential (MIC value 64.0 μg/mL). Only three seaweed extracts, i.e. H. siliquosa, B. bifurcata and Cystoseira tamariscifolia showed some cytotoxicity. To our knowledge, this is the first study on the antiprotozoal and antimycobacterial activity of brown algae from British and Irish waters. Copyright

Morphology, rbcL phylogeny and distribution of distromatic Ulva (Ulvophyceae, Chlorophyta) in Ireland and southern Britain

C.J. Loughnane, L.M. McIvor, F. Rindi, D.B. Stengel and M.D. Guiry. 2008. Morphology, rbcL phylogeny and distribution of distromatic Ulva (Ulvophyceae, Chlorophyta) in Ireland and southern Britain. Phycologia 47: 416–429. DOI: 10.2216/07-61.1 Species of Ulva occur worldwide in all aquatic habitats from freshwater through brackish to fully saline environments. The scarcity of stable morphological characters and the morphological plasticity linked to environmental conditions typical of species referred to this genus make identification and circumscription problematic. In Ireland and Britain the taxonomy of Ulva species has been uncertain, and only three species have been reported: Ulva lactuca, U. rigida and U. olivascens (later reassigned to Umbraulva olivascens). We reassessed the taxonomic status of this genus by combining morphological investigations with analyses of rbcL sequence data for 24 selected specimens from the Irish and southern British shores. This combination of methods allowed the identification of seven lineages, which were considered to represent the following species: Ulva rigida, U. scandinavica, U. lactuca, U. gigantea, U. rotundata, U. californica and Umbraulva olivascens. Of these, U. scandinavica, U. gigantea, U. rotundata and U. californica are newly reported; the distribution of U. olivascens was shown to be much wider than previously thought. The use of morphological features proved to be largely inconclusive and of limited value for circumscription of species. In the rbcL phylogeny, U. olivascens formed a sister clade to all other species. The results support the conspecificity of U. rigida, U. scandinavica and U. armoricana and the conspecificity of U. pseudocurvata and U. compressa already suggested in previous studies.

Using rbcL sequence data to reassess the taxonomic position of some Grateloupia and Dermocorynus species (Halymeniaceae, Rhodophyta) from the north-eastern Atlantic

Grateloupia is one of the most taxonomically complex genera of the Cryptonemiales. Of four species reported to occur in Ireland and Britain, only G. filicina (J.V. Lamouroux) C. Agardh and G. dichotoma J. Agardh are considered as native, with Grateloupia filicina var. luxurians A. Gepp & E.S. Gepp and G. doryphora (Montagne) Howe thought to be recent introductions. Sequence data from the plastid-encoded rbcL gene have been used to assist in clarifying the taxonomic position of these and other members of the Halymeniaceae from Ireland, Britain and neighbouring coasts. Molecular and morphological evidence indicate that the introduced alga G. filicina var. luxurians is only distantly related to the type species, G. filicina. It is here raised to species status as G. luxurians (A. Gepp & E.S. Gepp) R.J. Wilkes, L.M. McIvor & Guiry, stat. nov. A further species, Grateloupia minima P.L. Crouan & H.M. Crouan, has also been reported in the north-eastern Atlantic, but is currently considered as a seasonal or juvenile form of G. filicina. Based on morphological evidence and sequence data, G. minima is distinct from G. filicina, and is hereby reinstated. Although rarely reported, the closely related taxon, Dermocorynus montagnei P. L. Crouan & H. M. Crouan was also included in this study. Molecular and morphological data place Dermocorynus in a clade of Grateloupia species and we therefore propose that Dermocorynus be placed in synonymy with Grateloupia. The relationship between morphology and phylogeny within Grateloupia is discussed in the light of these results.

GELIDIELLA-CALCICOLA SP-NOV (RHODOPHYTA) FROM THE BRITISH-ISLES AND NORTHERN FRANCE

Gelidiella calcicola sp. nov. (Gelidiales, Gelidiaceae) is described from plants growing on loose-lying subtidal coralline algae and shells on southern, western and northern shores of the British Isles, and from Roscoff in Brittany, France. The species forms narrow, creeping axes attached at intervals by peg-like rhizoidal holdfasts. Irregularly pinnate branches arise at the points of attachment, arc downwards, and become attached and pinnately branched. No erect axes are formed; in all other described species of the genus Gelidiella at least some erect axes are formed from the creeping base. Internal rhizines, considered to be characteristic of all the genera of the Gelidiales except Gelidiella, are present in the medulla, but only at the attachment points. Surface cortical cells are large and usually arranged in chevron-like transverse rows. Tetrasporangia, formed only in the winter months, occur in lateral stichidia in chevron-like rows of 8–10 per row; they are spherical and apparently tetrahedrally o...

Taxonomy and distribution of Trentepohlia and Printzina (Trentepohliales, Chlorophyta) in the Hawaiian Islands

F. Rindi, A.R. Sherwood and M.D. Guiry. 2005. Taxonomy and distribution of Trentepohlia and Printzina (Trentepohliales, Chlorophyta) in the Hawaiian Islands. Phycologia 44: 270–284. The taxonomy and distribution of the species of Trentepohlia and Printzina in the Hawaiian Islands were studied by examination of field collections and herbarium specimens from Bernice P. Bishop Museum, Honolulu (BISH). Eight taxa attributable to these genera were recorded in the field: Printzina bosseae var. samoensis, P. effusa, P. lagenifera, Trentepohlia abietina, T. abietina var. tenue, T. arborum, Trentepohlia cf. flava and T. umbrina. The record of Trentepohlia aurea, based on some specimens deposited in BISH, is rejected. Growth and reproduction of some entities (P. bosseae var. samoensis, P. effusa, P. lagenifera and T. arborum) were examined in culture. In the Hawaiian Islands these algae grow primarily on tree bark and are rarely found on other types of substrata. Reproduction takes place by production of presumptive biflagellate gametangia in P. lagenifera, T. abietina and Trentepohlia cf. flava and by release of zoosporangia in P. bosseae var. samoensis and T. arborum; in P. effusa, both types of reproductive structures were found. Vegetative growth was the only form of reproduction found in culture for the species for which isolation was possible. The taxonomic position of the species collected and implications for the conservation of the Trentepohliaceae in tropical regions are discussed.

Antiprotozoal, Antimycobacterial and Cytotoxic Potential of Twenty-Three British and Irish Red Algae

As part of our continuing research on seaweeds, we have screened the crude extracts of 23 red marine algae collected from England and Ireland. The clinically important blood‐stage life forms of Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and Mycobacterium tuberculosis were used as test organisms in the in vitro assays. The selectivity of the extracts was determined by using mammalian skeletal myoblast (L6) cells. All algal extracts showed activity against T. brucei rhodesiense, with Corallina officinalis and Ceramium virgatum being the most potent (IC50 values 4.8 and 5.4 μg/ml), whilst none of the algal extracts inhibited the growth of T. cruzi. Except for Porphyra leucosticta, extracts from all seaweeds also showed leishmanicidal activity with IC50 values ranging from 16.5 to 85.6 μg/ml. Only the crude extract of Calliblepharis jubata showed some weak activity against Mycobacterium tuberculosis (MIC value 256 μg/ml), while the others were inactive at this concentration. Corallina officinalis was the only seaweed that displayed some marginal cytotoxicity (IC50 value 88.6 μg/ml), and all remaining extracts were non‐toxic towards L6 cells at 90 μg/ml concentration. To our knowledge, this is the first study reporting antiprotozoal and antimycobacterial activity of British and Irish red algae. Copyright

Morphology and systematics of Gelidiella tenuissima (Gelidiales, Rhodophyta) from Gran Canaria (Canary Islands, Spain)

Abstract Fertile male gametophytes of Gelidiella tenuissima are described for the first time, from cultured plants collected in Gran Canaria (Canary Islands, Spain). The morphology of male reproductive structures in this species is similar to other gametophytes referred to the Gelidiales, but different from the recently described male gametophyte of the type species of Gelidiella, G. acerosa. Morphological comparisons between these two species, using the male gametophyte and the tetrasporangial stichidia, and also molecular analyses, suggest that two different groups of species are included in the genus Gelidiella.