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Olivier De Clerck - One of the best experts on this subject based on the ideXlab platform.

  • Unexpected diversity patterns in Dictyota Fasciola and Dictyota Mediterranea (Dictyotales, Phaeophyceae)
    2017
    Co-Authors: Daniel Vitales, Olivier De Clerck, Frederique Steen, Joana Aragay, Teresa Garnatje, Amelia Gómez-garreta, Jordi Rull
    Abstract:

    Trabajo presentado en el XI Congreso de Ficologia de Latinoamerica y El Caribe y la IX Reunion Iberoamericana de Ficologia, celebrado en Cali (Colombia), del 5 al 10 de noviembre de 2017

  • historical biogeography of the highly diverse brown seaweed lobophora Dictyotales phaeophyceae
    Molecular Phylogenetics and Evolution, 2017
    Co-Authors: Claude Payri, Christophe Vieira, Frederik Leliaert, Olga Camacho, Suzanne Fredericq, Olivier De Clerck
    Abstract:

    The tropical to warm-temperate marine brown macroalgal genus Lobophora (Dictyotales, Phaeophyceae) recently drew attention because of its striking regional diversity. In this study we reassess Lobophora global species diversity, and species distributions, and explore how historical factors have shaped current diversity patterns. We applied a series of algorithmic species delineation techniques on a global mitochondrial cox3 dataset of 598 specimens, resulting in an estimation of 98–121 species. This diversity by far exceeds traditional diversity estimates based on morphological data. A multi-locus time-calibrated species phylogeny using a relaxed molecular clock, along with DNA-confirmed species distribution data was used to analyse ancestral area distributions, dispersal-vicariance-founder events, and temporal patterns of diversification under different biogeographical models. The origin of Lobophora was estimated in the Upper Cretaceous (−75 to −60 MY), followed by gradual diversification until present. While most speciation events were inferred within marine realms, founder events also played a non-negligible role in Lobophora diversification. The Central Indo-Pacific showed the highest species diversity as a result of higher speciation events in this region. Most Lobophora species have small ranges limited to marine realms. Lobophora probably originated in the Tethys Sea and dispersed repeatedly in the Atlantic (including the Gulf of Mexico) and Pacific Oceans. The formation of the major historical marine barriers (Terminal Tethyan event, Isthmus of Panama, Benguela upwelling) did not act as important vicariance events. Long-distance dispersal presumably represented an important mode of speciation over evolutionary time-scales. The limited geographical ranges of most Lobophora species, however, vouch for the rarity of such events.

  • Two New Species of the Genus Dictyota (Phaeophyceae: Dictyotales) from the Mexican Caribbean
    American Journal of Plant Sciences, 2015
    Co-Authors: Jorge G. Lozano-orozco, Abel Sentíes, Kurt M. Dreckmann, Olivier De Clerck, Jhoana Díaz-larrea
    Abstract:

    During a molecular characterization of the genus Dictyota J. V. Lamouroux (Phaeophyceae, Dictyotales) along the Mexican coasts of the Gulf of Mexico and the Mexican Caribbean, using psbA and cox1 genes, it was found that two particular collections did not match with the sequences published for a total of 39 species of Dictyota. For each gene, both collections diverged in high-uncorrected “p” distance values with respect to other related species. This high genetic divergence was corroborated by morphological analysis. Hence, we proposed Dictyota mayae J. Lozano-Orozco & Senties and Dictyota pedrochei J. Lozano-Orozco & Senties as new species.

  • Overgrowth and killing of corals by the brown alga Lobophora hederacea (Dictyotales, Phaeophyceae) on healthy reefs in New Caledonia: A new case of the epizoism syndrome
    Phycological Research, 2015
    Co-Authors: Christophe Vieira, Claude Payri, Olivier De Clerck
    Abstract:

    Summary Coral reef degradation is often associated with regime shifts from coral- to macroalgal-dominated reefs. These shifts demonstrate that under certain conditions (e.g. coral mortality, decrease in herbivory, increased nutrients supply) some macroalgae may overgrow corals. The outcome of the competition is dependent on algal aggressiveness and the coral susceptibility. In undisturbed reefs, herbivore grazing is regulating macroalgal cover, thus preventing the latter from overgrowing corals. However, some macroalgae have evolved strategies not only to outcompete corals but also to escape herbivory to some extent, allowing overgrowth of some coral species in undisturbed reefs. Epizoism represents one of those successful strategies, and has been previously documented with red algae, cyanobacteria and Lobophora variegata (Dictyotales, Phaeophyceae). Here we report a new case of epizoism leading to coral mortality, involving a recently described species of Lobophora, L. hederacea, overgrowing the coral Seriatopora caliendrum (Pocilloporidae) in undisturbed reefs in New Caledonia.

  • Biogeographic Affinities of Dictyotales from Madagascar: A Phylogenetic Approach
    Cryptogamie Algologie, 2015
    Co-Authors: Frederique Steen, Christophe Vieira, Frederik Leliaert, E. Claude Payri, Olivier De Clerck
    Abstract:

    During the Atimo Vatae research cruise of 2010, the seaweed flora of the southern coast of Madagascar was extensively sampled. Here we report on the species diversity and biogeographic affinities of the brown algal order Dictyotales, which was assessed using DNA-barcoding makers. Molecular identification resulted in 23 MOTU's belonging to 9 genera. From a biogeographic perspective Madagascar is considered to be part of the large tropical Western Indo-Pacific realm. However, only 3 out of 23 species confirmed this affinity. In contrast, species- and genus-level links to the more temperate coast of KwaZulu-Natal were as prominent (4 species) and 6 species represent endemic species. The remaining species were either widely distributed in tropical regions or their affinities were unclear. In conclusion, the Dictyotales data do not suggest the flora of southern Madagascar is unequivocally a part of the tropical Western Indo-Pacific realm, but rather a region of overlap, where more temperate species thrive in conjunction with some Indo West Pacific (IWP) elements.

Hiroshi Kawai - One of the best experts on this subject based on the ideXlab platform.

  • morphological and molecular evidence for two new species of padina Dictyotales phaeophyceae p sulcata and p calcarea from the central indo pacific region
    Phycologia, 2012
    Co-Authors: Takeaki Hanyuda, Eric Verheij, Stefano G A Draisma, Willem Prudhomme F Van Reine, Siew-moi Phang, Hiroshi Kawai
    Abstract:

    NI-NI-WIN, Hanyuda T., Draisma S.G.A., Verheij E., Prud'homme van Reine W.F., Lim P.-E., Phang S.-M., and Kawai H. 2012. Morphological and molecular evidence for two new species of Padina (Dictyotales, Phaeophyceae), P. sulcata and P. calcarea, from the central Indo-Pacific. Phycologia 51: 576–585. DOI: 10.2216/11-94.1 Two new species of Padina – 1. Padina sulcata sp. nov. and 2. P. calcarea sp. nov. – from Malaysia, Indonesia and Palau were described based on morphological and molecular phylogenetic observations. Padina sulcata was a three-layered species characterised by a covering of thick fibrous hairs from the base to the middle of the inferior surface (away from the in-rolled margin) of the thallus; conspicuous equally spaced hairlines that alternated between both frond surfaces; and broad, indusiate oogonial and tetrasporangial sori that occupied nearly the entire fertile zones, and the fertile zones were separated by sterile zones of equal width. Padina calcarea was a two-layered species character...

  • Taxonomic revision of the genus Lobophora (Dictyotales, Phaeophyceae) based on morphological evidence and analyses rbcL and cox3 gene sequences
    Phycologia, 2012
    Co-Authors: Zhongmin Sun, Takeaki Hanyuda, Jiro Tanaka, Phaik-eem Lim, Carlos Frederico D. Gurgel, Hiroshi Kawai
    Abstract:

    Sun Z., Hanyuda T., Lim P.E., Tanaka J., Gurgel C.F.D. and Kawai H. 2012. Taxonomic revision of the genus Lobophora (Dictyotales, Phaeophyceae) based on morphological evidence and analyses rbcL and...

  • Four new species of Padina (Dictyotales, Phaeophyceae) from the western Pacific Ocean, and reinstatement of Padina japonica
    Phycologia, 2010
    Co-Authors: Ni-ni-win, Stefano G A Draisma, Takeaki Hanyuda, Shogo Arai, Masayuki Uchimura, Anchana Prathep, Soe-htun, Hiroshi Kawai
    Abstract:

    Abstract Ni-Ni-Win, Hanyuda T., Arai S., Uchimura M., Prathep A., Draisma S.G.A., Soe-Htun and Kawai H. 2010. Four new species of Padina (Dictyotales, Phaeophyceae) from the western Pacific Ocean, and reinstatement of Padina japonica. Phycologia 49: 136–153. DOI: 10.2216/09-54.1 Molecular phylogenetic analyses of Padina species collected from the western Pacific Ocean using rbcL and mitochondrial cox3 genes revealed the occurrence of four genetically distinctive clades of unknown Padina species: clade A ( = Padina okinawaensis sp. nov.) from Ryukyu Islands (Japan), Hawaii, Indonesia and Thailand, clade B ( = Padina undulata sp. nov.), clade C ( = Padina terricolor sp. nov.) and clade D ( = Padina fasciata sp. nov.) from Ryukyu Islands (Japan). Morphologically, these new taxa are all bistratose species, and different from any known species in the following morphological features: P. okinawaensis sp. nov., reniform or circular thallus of entire margin with inconspicuous hair lines on the superior surface of...

  • seasonal stability of sulfuric acid accumulation in the Dictyotales phaeophyceae
    Phycological Research, 2005
    Co-Authors: Hideaki Sasaki, Akio Murakami, Hiroshi Kawai
    Abstract:

    SUMMARY Concerning the accumulation of S042- in cells, three types of species are known in the Dictyotales: (i) acidic type (high H2S04 accumulation); (ii) high MgS04 accumulation type; and (iii) nonacidic type (low S042- accumulation). Seasonal changes of intracellular pH and concentrations of inorganic ions were examined in six dictyotalean species. In acidic species (Dictyopteris prolifera (Okamura) Okamura and Spatoglossum eras-sum J. Tanaka), intracellular concentrations of S042- and H+ estimated by pH were high through all seasons. In high MgS04 accumulating species (Dictyotasp. and Padina arborescens Holmes), intracellular concentrations of S042- and Mg2+ were high through all seasons. In nonacidic species (Dictyota dichotoma (Hudson) Lamouroux and Dictyopteris undulata Holmes), intracellular concentration of sulfuric acid ion was low all year round.

  • Inorganic ion compositions in brown algae, with special reference to sulfuric acid ion accumulations
    Asian Pacific Phycology in the 21st Century: Prospects and Challenges, 2004
    Co-Authors: Hideaki Sasaki, Hironao Kataoka, Akio Murakami, Hiroshi Kawai
    Abstract:

    Cellular pH estimated from cell extract pH and the ion compositions of major inorganic ions (Na+, NH4+, K+, Mg2+, Ca2+,Cl−, Br−, NO3 −, SC4 2−) were studied by ion chromatography in 61 species of 10 orders (Dictyotales, Desmarestiales, Ectocarpales, Chordariales, Scytosiphonales, Dictyosiphonales, Cutleriales, Sporochnales, Laminariales and Fucales) of Phaeophyceae. Three species in the order Dictyotales, Dictyopteris sp., Spatoglossum solierii (Chauv.) Kiitzing and Zonaria stipitata Tanaka et K. Nozawa, were newly found to be highly acidic (pH 0.6 and 1.4 within cells), in addition to previously reported dictyotalean species, Dictyopteris Iatiuscula (Okamura) Okamura, D. prolifera (Okamura) Okamura, D. repens (Okamura) Borgesen and Spatoglossum crassum J. Tanaka. They all contained high concentrations of SC4 2− perhaps within the vacuoles. Furthermore, Delamarea attanuata (Kjellman) Rosenvinge (Dictyosiphonales) and Thalassiophyllum clathrus (Gmel.) P. et R. (Laminariales) were shown to contain relatively high concentrations of SC4 2− balanced by relatively high concentrations of Ca2+.

Wendy A. Nelson - One of the best experts on this subject based on the ideXlab platform.

J. A. Phillips - One of the best experts on this subject based on the ideXlab platform.

  • Systematics of the Australian species of Dictyopteris (Dictyotales, Phaeophyceae)
    Australian Systematic Botany, 2000
    Co-Authors: J. A. Phillips
    Abstract:

    Eleven species of Dictyopteris are recognised for Australia. The tropical species D. australis (Sonder) Askenasy, D. deliculata Lamouroux, D. plagiogramma (Montagne) Vickers, D. repens (Okamura) Borgesen, D. serrata (Areschoug) Hoyt and D. woodwardia (R. Brown ex Turner) C. Agardh are recorded for warmer coasts, although isolated populations of D. australis occur in the Gulfs region of South Australia. Dictyopteris acrostichoides (J. Agardh) Bornet and D. crassinervia (Zanardini) Schmidt are endemic to eastern Australia, with D. acrostichoides also extending to the eastern end of the southern coast. Dictyopteris gracilis Womersley and D. muelleri (Sonder) Reinbold occur on temperate southwestern and southern coasts. The west coast species Dictyopteris secundispiralis J. A. Phillips sp. nov. is described, and D. nigricans Womersley is reduced to a taxonomic synonym of D. muelleri. Detailed comparative studies undertaken on these species have identified several new taxonomically-informative characters useful for generic circumscription and species discrimination. Thallus branches which have a cortical layer composed of large cuboidal cells and reproductive organs scattered in fertile zones are additional characters which characterise the genus. Australian species of Dictyopteris are now well defined by differences in several distinctive vegetative and reproductive characters such as thallus morphology, blade cell layer number, structure of the thallus apex, presence of marginal teeth and lateral veins, distribution and structure of hair bundles, sporangia, oogonia and antheridial sori.

  • Dictyopteris serrata (Dictyotales, Phaeophyceae): A Little Known Algal Species Newly Recorded from Australia
    Botanica Marina, 1998
    Co-Authors: J. A. Phillips, John M Huisman
    Abstract:

    The brown alga Dictyopteris serrata (Areschoug) Hoyt (Dictyotales, Phaeophyceae) is reported from the coast of western Australia, representing the first reliable record of this species from outside the south-western Indian Ocean. Distinguishing features of D. serrata are: a broad thallus with marginal teeth, veins extending from the midrib obliquely towards the blade margin, and embedded tetrasporangia borne singly or in small groups of usually two or three in fertile zones on the upper thallus branches. The species is apparently closely related to the North American Dictyopteris hoytii Taylor, and previously perceived vegetative differences are questioned. The two species may differ in tetrasporangial distribution, but further studies are required to describe the sporangia of D. hoytii in greater detail.

  • Flagellate spores in Homoeostrichus olsenii Womersley (Dictyotales, Phaeophyceae): The largest known motile reproductive cells of marine macroalgae
    Phycologia, 1994
    Co-Authors: J. A. Phillips, M. N. Clayton
    Abstract:

    Abstract The biflagellate spores of Homoeostrichus olsenii Womersley are the largest motile reproductive cells reported for any macroalga. They are also the first zoospores discovered in the Dictyotales and are considered to represent an intermediate stage in the evolution of the typically large non-flagellatedictyotalean spore from the small zoospores. characteristic of most orders of the Phaeophyceae. Zoospores of H. olsenii have a large, elongate nucleus, basal bodies which are among the longest reported for algal motile cells and a conspicuous, fibrous, nucleus-basal body connector, a feature which is thus clearly demonstrated in the Phaeophyceae. The proximal ends of the basal bodies terminate close to the nucleus and the basal bodies consequently do not show the same orientation as most other phaeophycean motile cells.

  • Stoechospermum (Dictyotales, Phaeophyceae): a poorly known algal genus newly recorded in Australia
    Phycologia, 1993
    Co-Authors: J. A. Phillips, Jiro Tanaka, R. J. King, Anika S. Mostaert
    Abstract:

    Australia has a rich diversity of species belonging to the order Dictyotales. Sixteen genera and 41 species are recorded for temperate southern coasts (Womersley 1987) and 13 genera and 43 species for tropical to warm temperate northern coasts (Lewis 1985) giving a total of 17 genera and 73 species. Stoe­ chospermum is the only genus in the order not previously recorded from Australian coasts. Kiitzing (1843) erected the genus Stoechospermum and in­ cluded Zonaria marginata C. Agardh as Stoechospermum marginatum (c. Agardh) Kiitzing. Subsequently, four more species were added to the genus: Stoechospermum patens J. Agardh (1848) from the Red Sea, Stoechospermum maculatum (J. Agardh) J. Agardh (1848) from India, Stoechospermum polypodioides (Lamouroux) J. Agardh (1848) from the Antilles and Stoechospermum suhrii Kiitzing (1859) from South Africa. S. maculatum and S. patens were later reduced to synonyms of S. marginatum (Zanardini 1858; Papenfuss 1977) and S. suhrii was transferred to Dilophus (Papenfuss 1940). The status of S. polypodioides, known only from the type specimen, is not clarified. Stoechospermum is a distinctive genus characterized by elongate sporangial sori oriented parallel to the thallus margin, and this feature is not found elsewhere in the Dictyotales. S. marginatum has a reported geographical distribution (Fig. I) from Inthaca Peninsula, Mozambique (26°S, 33°E, AD 57995, Isaac, 30.vi.1954) north to the Red Sea and south along the Indian subcontinent to Sri Lanka (6-100N, 80-82°E, Durair­ atnam 1961). This paper extends the distribution to the north­ ern Western Australian coastline and describes the thallus morphology and vegetative anatomy along with the arrange­ ment and structure of sporangial sori of Australian specimens.

  • Taxonomy and reproduction in Australian species of Diliphus (Dictyotales, Phaeophyta)
    Australian Systematic Botany, 1992
    Co-Authors: J. A. Phillips
    Abstract:

    Eight species of Dilophus are recognised for Australia. Detailed descriptions are given for five species, D. fastigiatus, D. gunnianus, D. intermedius, D. marginatus and D. robustus. D. moniliformis and D. crinitus from Western Australia and D. decumbens from subantarctic Macquarie I. remain poorly known. Sporophytes and gametophytes are reported for the five species providing first records of sporophytes of D. robustus, female gametophytes of D. intermedius, and both male and female gametophytes of D. robustus and D. marginatus. The arrangement and structure of sporangia and gametangia have been intensively studied and many reproductive characters not previously used in species discrimination have been incorporated into species' descriptions and used to develop species' concepts. Species are delimited on the following combination of characters: arrangement, size and structure of sporangia, arrangement and structure of gametangia, and the number of medullary cell layers.

Judy E. Sutherland - One of the best experts on this subject based on the ideXlab platform.