The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Sung-min Boo - One of the best experts on this subject based on the ideXlab platform.
-
Rhizoidal cortication in the red algal genus Ceramium (Ceramiaceae, Ceramiales) : Two developmental patterns
Cryptogamie Algologie, 2004Co-Authors: Tae Oh Cho, Sung-min Boo, James N. Norris, Suzanne FredericqAbstract:Lors de l'etude du developpement de la morphologie et de la reproduction chez deux especes de Ceramium (Ceramiaceae, Rhodophyta), etudiant notamment la cortication nodale, deux modes differents de developpement des cellules corticantes rhizoidales, ont ete trouves. Chez C. personatum (espece a cortication incomplete), les cellules corticantes rhizoidales allongees sont produites seulement de facon basipete a partir des cellules periaxiales des noeuds ; chez C. nitens (espece a cortication complete), elles sont produites a la fois de facon acropete et basipete a partir des cellules periaxiales et fonctionnent comme les cellules corticales internes qui produisent les massifs de cellules corticales externes dans tout le thalle. Les cellules corticantes rhizoidales de C. personatum ressemblent typiquement a celles de C. californicum, tandis que celles de C. nitens ressemblent a celles de C. boydenii. Les structures femelles de reproduction de C. personatum sont decrites ici pour la premiere fois et sont conformes a celles des autres especes connues de Ceramium. Quelques especes, comme C. nitens, ont des filaments corticants de nature rhizoidale et une cortication complete, des caracteristiques du genre Campylaephora ; cependant, ces taxons peuvent en etre distingues par l'existence d'une cortication separee entre les cellules axiales distales et proximales alors que Campylaephora a des synapses secondaires entre les cellules corticantes rhizoidales. Nos observations confirment la necessite d'une profonde revision des genres Ceramium and Camplaephora.
-
NEW INSIGHTS IN THE TAXONOMY OF THE Ceramium SINICOLA COMPLEX: RESURRECTION OF Ceramium INTERRUPTUM (CERAMIACEAE, RHODOPHYTA) 1
Journal of Phycology, 2003Co-Authors: T. O. Cho, Suzanne Fredericq, Steven N. Murray, Sung-min BooAbstract:Phylogenetic relationships of the Ceramium sinicola complex (C. interruptum and C. sinicola) including C. codicola were studied using nucleotide sequences of rbcL and small subunit rDNA, and the RUBISCO spacer was used for sequence comparison of each species. A reassessment of the taxonomic rank and the evolutionary trend within the complex was inferred from a comparative morphological study and molecular data sets based on 11 samples from eight populations from the Pacific coast of the United States and Mexico. Intraspecific relationships were poorly resolved, but the resurrection of C. interruptum as a distinct species was strongly supported by both morphological and molecular data. Ceramium interruptum is distinguished by the combination of the following features: thalli uncorticated at the first internode above the dichotomy, presence of four corticating filaments, 7-11 segments between branching points, rhizoids digitate, and epiphytic on a variety of hosts. Our molecular analyses show that C. sinicola is the sister group to C. codicola, and C. interruptum is basal to them. These phylogenetic relationships allowed for an assessment of the trend in the evolution of cortication pattern and attachment mode to the host.
-
25 Proposal of a new red algal genus in the ceramieae (ceramiaceae, ceramiales)
Journal of Phycology, 2003Co-Authors: T. O. Cho, Suzanne Fredericq, Max H. Hommersand, Sung-min BooAbstract:A new genus is proposed to accommodate four species belonging in the Ceramium flaccidum complex based on comparative vegetative morphology and rbcL sequence analysis: C. flaccidum (Harvey ex Kuetzing) Ardissone (1871), C. gracillimum, C. Agardh (1824), C. fimbriatum S. & G. (1924) and C. rectocorticum Dawson 1950. Comparative rbcL sequence analysis indicates that this complex forms a distinct monophyletic clade separate from other Ceramium species. Although C. flaccidum has been placed in Hormoseras Kuetzing 1841 (as H. flaccidum Harvey ex Kuetzing 1862), the type species of Hormoceras is Ceramium diaphanum. The new genus is characterized by alternate branching, incomplete cortication, production of three cortical filament initials of which the basipetal initial divides horizontally, and unicellular rhizoids terminating in pad-like structures produced from periaxial cells. Cortical filament development is discussed for related genera in the tribe Ceramieae (Campylaephora, Carpoblepharis, Centroceras, Ceramium, Corallophila, Herpochondria, Microcladia, Reinboldiella). RbcL-based phylogenies indicate that the new genus is sister to Centroceras, a genus possessing three cortical filament initials. The phylogenetic relationships within the tribe may correlate with cortication patterns that characterize each genus
-
Ceramium INKYUII SP. NOV. (CERAMIACEAE, RHODOPHYTA) FROM KOREA: A NEW SPECIES BASED ON MORPHOLOGICAL AND MOLECULAR EVIDENCE1
Journal of Phycology, 2003Co-Authors: Tae Oh Cho, Suzanne Fredericq, Sung-min BooAbstract:Ceramium inkyuii sp. nov. is newly described based on samples collected from the east coast of Korea and compared with similar species such as C. paniculatum and C. tenerrimum. The new species is characterized by pseudo-dichotomously branched thalli with a twist in the upper part, a single row of spines on the abaxial side, strongly inrolled apices, and the presence of gland cells. In contrast, C. paniculatum has alternate branches and lacks gland cells, and C. tenerrimum is spineless and also lacks gland cells. Ceramium inkyuii was observed to be an annual species producing tetrasporangia in the spring to summer and cystocarps in the fall. Plastid-encoded rbcL and nuclear small subunit (SSU) rDNA sequences were determined in four samples of C. inkyuii from different locations and six samples of four putative relatives. All four C. inkyuii replicates from three different locations had identical sequences of each gene, and the interspecific sequence divergences were enough to warrant its natural entity. The phylogenies of the rbcL and SSU rDNA sequences also indicate the monophyly of C. inkyuii. The spinous C. inkyuii was more closely related to the spineless C. tenerrimum than to the spinous C. paniculatum.
-
Developmental morphology of a poorly documented alga, Ceramium recticorticum (Ceramiaceae, Rhodophyta), from the Gulf of California, Mexico
Cryptogamie Algologie, 2002Co-Authors: Tae Oh Cho, Rafael Riosmena-rodríguez, Sung-min BooAbstract:Nous avons etudie la morphologie du thalle, de la reproduction et du developpement de Ceramium recticorticum Dawson. Les thalles ont une ramification alterne et ont quatre cellules periaxiales avec quatre a cinq cellules pseudoperiaxiales. Les cellules corticales acropetes et basipetes sont produites par la division transversale des cellules periaxiales et pseudoperiaxiales et sont rectangulaires, allongees horizontalement et disposees regulierement en quatre a cinq colonnes et en rangees. Les spermatocystes sont produits du cote adaxial des derniers verticilles des rameaux superieurs. Les cystocarpes sont spheriques et entoures par 2-4 rameaux involucraux. Les tetrasporocystes sont produits en series opposees, completement recouverts par des cellules corticales et disposes en verticilles. Le developpement des spermatocystes et des cystocarpes sont decrits pour la premiere fois et confirment que la description du genre Ceramium recticorticum est semblable a celle de C. fimbriatum Setchell et Gardner, C. flaccidum (Kutzing) Ardissone et C gracillimum (Kutzing) Griffiths et Harvey ex Harvey var. byssoideum (Harvey) Mazoyer en ayant en commun une cellule corticale basipete horizontale produite par la division transversale des cellules periaxiales ainsi que des rhizoides composes de filaments unicellulaires avec des bourrelets produits par les cellules periaxiales. Ces taxons doivent etre consideres comme un groupe d'especes voisines.
Lena Kautsky - One of the best experts on this subject based on the ideXlab platform.
-
LOCAL ADAPTATION OF Ceramium TENUICORNE (CERAMIALES, RHODOPHYTA) WITHIN THE BALTIC SEA1
Journal of Phycology, 2006Co-Authors: Lena Bergström, Lena KautskyAbstract:Ceramium tenuicorne (Kutzing) Waern is a red alga that is widely distributed in the brackish Baltic Sea. We studied the growth response of Ceramium to low salinity and nutrient enrichment, using isolades from two regions of the Baltic Sea where the alga approaches its inner distribution limit. Ecotypic differentiation was observed in that differences in growth response among isolates corresponded to salinity conditions in their regions of origin. Isolates from the Gulf of Bothnia (4 psu) had inherently lower growth rates that were not increased when transferred to higher salinity, but were better adapted to very low salinity levels than isolates from the Baltic Proper (7 psu). Further, the results indicate that Ceramium from different regions of the Baltic Sea vary in their responses to nutrient enrichment. The observed differences may be best described as a quantitative difference in the proportion of isolates with hyposaline adaptation. The results indicate that the wide distribution of Ceramium in the Baltic Sea is better explained by the occurrence of locally adapted genotypes than by a generalist life strategy, and provide example of adaptive differentiation in a marine edge environment.
-
Local adaptation in Ceramium tenuicorne (Ceramiales, Rhodophyta) within the Baltic Sea salinity gradient
2005Co-Authors: Lena Bergström, Lena KautskyAbstract:Local adaptation in Ceramium tenuicorne (Ceramiales, Rhodophyta) within the Baltic Sea salinity gradient
-
Morphological and genetic differentiation of Fucus vesiculosus in the brackish Baltic Sea
Journal of Phycology, 2005Co-Authors: Lena Bergström, Andrei Tatarenkov, Rita B. Jönsson, Kerstin Johannesson, Lena KautskyAbstract:The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. Even more recently, increased nutrient loading due to human activities has affected the growth rate of species, with potential effects on their competitive interactions and responses to other regulating factors. I have investigated the potential effects of low salinity and nutrient enrichment on the distributional ranges of two marine macroalgae with a wide distribution in the Baltic Sea, the red alga Ceramium tenuicorne (Kutz.) Waern and the brown alga Fucus vesiculosus L. A field study in the northern Baltic Sea indicated a strong relationship between the community structure of macroalgae and abiotic factors even on a small, local scale. The abiotic factors are potentially modulated by eutrophication, which may have a strong effect on the depth distribution and abundance of macroalgae. On a regional scale, laboratory experiments suggested that nutrient enrichment is unlikely to affect the distribution of Ceramium and Fucus along the salinity gradient. Growth in Ceramium from the Baltic Proper was enhanced by nitrate and phosphate, but the response did not override growth constraints due to low salinity. Ceramium from the Gulf of Bothnia had an inherently lower growth rate that was not positively affected by nitrate and phosphate increase. In Fucus vesiculosus, reproductive performance was impaired by nitrate and phosphate levels corresponding to ambient levels in eutrophicated areas of the Baltic Sea, when measured by their effect on zygote attachment, germination, and rhizoid development.The wide distribution of Ceramium in the inner Baltic Sea is probably related to local adaptation, rather than a generalized tolerance of different salinity levels. Ecotypic differences were observed when comparing strains from the Baltic Proper (salinity 7 psu) and the Gulf of Bothnia (4 psu). A high rate of vegetative reproduction was evident, although sexual reproduction was occasionally observed in salinity 4. In Fucus vesiculosus, genetic and morphological analyses of sympatric and allopatric populations of the common, vesicular, morphotype and a dwarf morphotype, characteristic for the Gulf of Bothnia, showed that the dwarf morphotype represents a separate evolutionary lineage. Also, vegetative reproduction was observed in Fucus for the first time, as supported by genetic and experimental data. The results show that the biota of the inner Baltic Sea may have unique adaptive and genetic properties, and that it is highly relevant to consider subspecies diversity in Baltic Sea management.
-
Reproductive strategies of Ceramium tenuicorne near its inner limit in the brackish Baltic Sea
Botanica Marina, 2003Co-Authors: Lena Bergström, E. Bruno, B. Eklund, Lena KautskyAbstract:Reproductive strategies of Ceramium tenuicorne near its inner limit in the brackish Baltic Sea
Jan Rueness - One of the best experts on this subject based on the ideXlab platform.
-
A molecular approach to investigate the phylogenetic basis of three widely used species groups in the red algal genus Ceramium (Ceramiales, Rhodophyta)
Phycologia, 2005Co-Authors: Morten Skage, Tove M. Gabrielsen, Jan RuenessAbstract:M. SKAGE, T.M. GABRIELSEN AND J. RUENESS. 2005. A molecular approach to investigate the phylogenetic basis of three widely used species groups in the red algal genus Ceramium (Ceramiales, Rhodophyta). Phycologia 44: 353‐360. The taxonomy of Ceramium (Ceramiales, Rhodophyta) is difficult because of large and complex morphological variation. Three species groups are often recognised; one group that can develop fully corticated internodes, one group with ecorticate internodes, and one group with cortical spines. Two different molecular markers (the plastid rubisco spacer and one part of the large subunit [LSU] of nuclear ribosomal DNA) were used to investigate whether the three species groups have a phylogenetic basis. Sequence analyses of 15‐17 North Atlantic species of Ceramium revealed highly conserved partial LSU sequences, whereas the rubisco spacer region was variable among, as well as within several species. Analyses of the rubisco spacer sequences, and in particular the combined data set, produced fairly resolved phylogenies with several well-supported relationships that were highly incongruent with the informal species groups. These results suggest that cortical spines and internode cortication have evolved several times in Ceramium.
-
Phylogeny and interfertility of North Atlantic populations of ‘Ceramium strictum’ (Ceramiales, Rhodophyta): how many species?
European Journal of Phycology, 2003Co-Authors: Tove M. Gabrielsen, Christian Brochmann, Jan RuenessAbstract:‘Ceramium strictum’ is an illegitimate name that has been used in a wide sense to encompass non-spiny, partially corticated North Atlantic populations of Ceramium. At the other extreme, several species have been recognized even within a single restricted geographic region (Skagerrak-Baltic). We combined molecular and interfertility analyses to assess relationships among samples of ‘C. strictum’ from five geographic regions (Skagerrak-Baltic, northeastern America, the Canary Islands, western Norway and the British Isles), with emphasis on the Skagerrak-Baltic Sea salinity gradient. Sequences of the nuclear ribosomal internal transcribed spacer 2 (ITS2) and the plastid Rubisco spacer region were obtained from these samples, from two other partially corticated species (C. siliquosum and C. deslongchampsii) and from two species described as fully corticated (C. pallidum and C. secundatum). In phylogenetic analyses using the most divergent species, C. deslongchampsii, as an outgroup, C. secundatum was basal to...
-
Molecular analyses elucidate the taxonomy of fully corticated, nonspiny species of Ceramium (Ceramiaceae, Rhodophyta) in the British Isles
Phycologia, 2002Co-Authors: Christine A. Maggs, Lynne Mcivor, Jan Rueness, Barbara A. Ward, Chloe M. Evans, Michael J. StanhopeAbstract:Abstract Four fully corticated nonspiny species of Ceramium are currently recognized in the British Isles, all formerly confused under the illegitimate name Ceramium rubrum (Hudson) C. Agardh. One of these species was known briefly as C. nodulosum (Lightfoot) Ducluzeau but, in 1996, P.C. Silva and others [Univ. Calif. Publ. Bot. 79] showed that this is a later homonym of C. nodulosum de Candolle and advocated conserving C. rubrum with a neotype. As an alternative to this, we investigated whether the name C. virgatum Roth 1797 might be available for this species. The aim of the present study was to typify C. virgatum, in the context of better characterizing this and the other fully corticated species of Ceramium that occur in the British Isles, by analysis of plastid DNA (cpDNA) restriction fragment length polymorphism (RFLP) or rbcL sequences (or both) of each species from various sites, including their type localities. The lectotype of C. virgatum is Roth's illustration of a Ceramium specimen from Eckwar...
-
Observations on Ceramium tenuicorne (Rhodophyta) and its reproduction
Cryptogamie Algologie, 2002Co-Authors: Jan Rueness, Tove M. Gabrielsen, Lene DüwelAbstract:Observations sur Ceramium tenuicorne (Rhodophyta) et sa reproduction. Ceramium tenuicorne (Kutzing) Waern (incluant C. gobii Waern) est une algue rouge commune des regions de Skagerrak et de la mer Baltique. Un cycle de reproduction de type Polysiphonia et une reproduction asexuee par paraspores, precedemment demontres en cultures pour cette espece, ont ete confirmes. En complement, un type specifique de structure reproductive (les 'monosporocystes de Gobi') a ete decrit sur du materiel recolte en mer Baltique. Ce type de structure a ete utilise par Waern (1992) pour distinguer sa nouvelle espece: Ceramium gobii. Nous avons etudie la formation et la fonction des 'mono-sporocystes de Gobi' en culture; ce sont des apex modifies chez lesquels les cellules se transforment directement en gros elements arrondis qui se detachent et se developpent en une nouvelle generation de thalles identiques. Ces structures doivent donc etre assimilees a des propagules vegetatives plutot que considerees comme des sporocystes. Des tetra-sporocystes ont occasionnellement ete trouves sur des individus portant des parasporo-cystes ou des propagules vegetatives. Les tetraspores issues de ces individus ne se sont generalement pas developpe mais, dans quelques cas, des gametophytes matures ont ete obtenus, de meme que des thalles portant soit des spermatocystes et des parasporocystes, soit des spermatocystes et des propagules vegetatives. Une interconnection entre des modes de reproduction sexuee et asexuee a donc ete demontree.
-
Lectotypification of the red alga Ceramium secundatum Lyngbye
Nordic Journal of Botany, 1994Co-Authors: Sung-min Boo, Jan RuenessAbstract:Ceramium secundatum is typified by a cystocarp-bearing specimen from the Faroes in Lyngbye's herbarium (C). This specimen resembles that illustrated by Lyngbye (1819, Tab. 37 A). The type locality was revisited in 1992 and C. secundatum and other Ceramium spp. were collected.
Lena Bergström - One of the best experts on this subject based on the ideXlab platform.
-
LOCAL ADAPTATION OF Ceramium TENUICORNE (CERAMIALES, RHODOPHYTA) WITHIN THE BALTIC SEA1
Journal of Phycology, 2006Co-Authors: Lena Bergström, Lena KautskyAbstract:Ceramium tenuicorne (Kutzing) Waern is a red alga that is widely distributed in the brackish Baltic Sea. We studied the growth response of Ceramium to low salinity and nutrient enrichment, using isolades from two regions of the Baltic Sea where the alga approaches its inner distribution limit. Ecotypic differentiation was observed in that differences in growth response among isolates corresponded to salinity conditions in their regions of origin. Isolates from the Gulf of Bothnia (4 psu) had inherently lower growth rates that were not increased when transferred to higher salinity, but were better adapted to very low salinity levels than isolates from the Baltic Proper (7 psu). Further, the results indicate that Ceramium from different regions of the Baltic Sea vary in their responses to nutrient enrichment. The observed differences may be best described as a quantitative difference in the proportion of isolates with hyposaline adaptation. The results indicate that the wide distribution of Ceramium in the Baltic Sea is better explained by the occurrence of locally adapted genotypes than by a generalist life strategy, and provide example of adaptive differentiation in a marine edge environment.
-
Local adaptation in Ceramium tenuicorne (Ceramiales, Rhodophyta) within the Baltic Sea salinity gradient
2005Co-Authors: Lena Bergström, Lena KautskyAbstract:Local adaptation in Ceramium tenuicorne (Ceramiales, Rhodophyta) within the Baltic Sea salinity gradient
-
Morphological and genetic differentiation of Fucus vesiculosus in the brackish Baltic Sea
Journal of Phycology, 2005Co-Authors: Lena Bergström, Andrei Tatarenkov, Rita B. Jönsson, Kerstin Johannesson, Lena KautskyAbstract:The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. Even more recently, increased nutrient loading due to human activities has affected the growth rate of species, with potential effects on their competitive interactions and responses to other regulating factors. I have investigated the potential effects of low salinity and nutrient enrichment on the distributional ranges of two marine macroalgae with a wide distribution in the Baltic Sea, the red alga Ceramium tenuicorne (Kutz.) Waern and the brown alga Fucus vesiculosus L. A field study in the northern Baltic Sea indicated a strong relationship between the community structure of macroalgae and abiotic factors even on a small, local scale. The abiotic factors are potentially modulated by eutrophication, which may have a strong effect on the depth distribution and abundance of macroalgae. On a regional scale, laboratory experiments suggested that nutrient enrichment is unlikely to affect the distribution of Ceramium and Fucus along the salinity gradient. Growth in Ceramium from the Baltic Proper was enhanced by nitrate and phosphate, but the response did not override growth constraints due to low salinity. Ceramium from the Gulf of Bothnia had an inherently lower growth rate that was not positively affected by nitrate and phosphate increase. In Fucus vesiculosus, reproductive performance was impaired by nitrate and phosphate levels corresponding to ambient levels in eutrophicated areas of the Baltic Sea, when measured by their effect on zygote attachment, germination, and rhizoid development.The wide distribution of Ceramium in the inner Baltic Sea is probably related to local adaptation, rather than a generalized tolerance of different salinity levels. Ecotypic differences were observed when comparing strains from the Baltic Proper (salinity 7 psu) and the Gulf of Bothnia (4 psu). A high rate of vegetative reproduction was evident, although sexual reproduction was occasionally observed in salinity 4. In Fucus vesiculosus, genetic and morphological analyses of sympatric and allopatric populations of the common, vesicular, morphotype and a dwarf morphotype, characteristic for the Gulf of Bothnia, showed that the dwarf morphotype represents a separate evolutionary lineage. Also, vegetative reproduction was observed in Fucus for the first time, as supported by genetic and experimental data. The results show that the biota of the inner Baltic Sea may have unique adaptive and genetic properties, and that it is highly relevant to consider subspecies diversity in Baltic Sea management.
-
Reproductive strategies of Ceramium tenuicorne near its inner limit in the brackish Baltic Sea
Botanica Marina, 2003Co-Authors: Lena Bergström, E. Bruno, B. Eklund, Lena KautskyAbstract:Reproductive strategies of Ceramium tenuicorne near its inner limit in the brackish Baltic Sea
Suzanne Fredericq - One of the best experts on this subject based on the ideXlab platform.
-
Two creeping Ceramium species (Ceramiaceae, Rhodophyta) from the Florida Keys: C. reptans sp. nov. and recircumscription of C. codii (Richards) Mazoyer
Phycologia, 2006Co-Authors: T. O. Cho, Suzanne FredericqAbstract:Abstract On the basis of comparative morphology, a new creeping Ceramium species with incomplete and narrow nodal cortication, C. reptans sp. nov. is described from the Florida Keys, USA, where it co-occurs epiphytically with C. codii on the same host, Hypnea spinella. Ceramium reptans sp. nov. is recognized by a prostrate axis producing unbranched upright axes dorsally; five periaxial cells per axial cell; three cortical cells cut off per periaxial cell, with the first acropetal cortical cell becoming the pseudoperiaxial cell that extends longitudinally parallel to the level of neighboring periaxial cells, a second acropetal and third basipetal horizontal cortical cell; and cruciately divided tetrasporangia in whorls bulging from a single node appressed to the contiguous node below on upright axes, 3–6 segments below the apex. Ceramium codii, described from Bermuda, is recognized by a prostrate axis producing unbranched, upright axes dorsally, four periaxial cells per axial cell, three cortical cells cut...
-
Rhizoidal cortication in the red algal genus Ceramium (Ceramiaceae, Ceramiales) : Two developmental patterns
Cryptogamie Algologie, 2004Co-Authors: Tae Oh Cho, Sung-min Boo, James N. Norris, Suzanne FredericqAbstract:Lors de l'etude du developpement de la morphologie et de la reproduction chez deux especes de Ceramium (Ceramiaceae, Rhodophyta), etudiant notamment la cortication nodale, deux modes differents de developpement des cellules corticantes rhizoidales, ont ete trouves. Chez C. personatum (espece a cortication incomplete), les cellules corticantes rhizoidales allongees sont produites seulement de facon basipete a partir des cellules periaxiales des noeuds ; chez C. nitens (espece a cortication complete), elles sont produites a la fois de facon acropete et basipete a partir des cellules periaxiales et fonctionnent comme les cellules corticales internes qui produisent les massifs de cellules corticales externes dans tout le thalle. Les cellules corticantes rhizoidales de C. personatum ressemblent typiquement a celles de C. californicum, tandis que celles de C. nitens ressemblent a celles de C. boydenii. Les structures femelles de reproduction de C. personatum sont decrites ici pour la premiere fois et sont conformes a celles des autres especes connues de Ceramium. Quelques especes, comme C. nitens, ont des filaments corticants de nature rhizoidale et une cortication complete, des caracteristiques du genre Campylaephora ; cependant, ces taxons peuvent en etre distingues par l'existence d'une cortication separee entre les cellules axiales distales et proximales alors que Campylaephora a des synapses secondaires entre les cellules corticantes rhizoidales. Nos observations confirment la necessite d'une profonde revision des genres Ceramium and Camplaephora.
-
NEW INSIGHTS IN THE TAXONOMY OF THE Ceramium SINICOLA COMPLEX: RESURRECTION OF Ceramium INTERRUPTUM (CERAMIACEAE, RHODOPHYTA) 1
Journal of Phycology, 2003Co-Authors: T. O. Cho, Suzanne Fredericq, Steven N. Murray, Sung-min BooAbstract:Phylogenetic relationships of the Ceramium sinicola complex (C. interruptum and C. sinicola) including C. codicola were studied using nucleotide sequences of rbcL and small subunit rDNA, and the RUBISCO spacer was used for sequence comparison of each species. A reassessment of the taxonomic rank and the evolutionary trend within the complex was inferred from a comparative morphological study and molecular data sets based on 11 samples from eight populations from the Pacific coast of the United States and Mexico. Intraspecific relationships were poorly resolved, but the resurrection of C. interruptum as a distinct species was strongly supported by both morphological and molecular data. Ceramium interruptum is distinguished by the combination of the following features: thalli uncorticated at the first internode above the dichotomy, presence of four corticating filaments, 7-11 segments between branching points, rhizoids digitate, and epiphytic on a variety of hosts. Our molecular analyses show that C. sinicola is the sister group to C. codicola, and C. interruptum is basal to them. These phylogenetic relationships allowed for an assessment of the trend in the evolution of cortication pattern and attachment mode to the host.
-
25 Proposal of a new red algal genus in the ceramieae (ceramiaceae, ceramiales)
Journal of Phycology, 2003Co-Authors: T. O. Cho, Suzanne Fredericq, Max H. Hommersand, Sung-min BooAbstract:A new genus is proposed to accommodate four species belonging in the Ceramium flaccidum complex based on comparative vegetative morphology and rbcL sequence analysis: C. flaccidum (Harvey ex Kuetzing) Ardissone (1871), C. gracillimum, C. Agardh (1824), C. fimbriatum S. & G. (1924) and C. rectocorticum Dawson 1950. Comparative rbcL sequence analysis indicates that this complex forms a distinct monophyletic clade separate from other Ceramium species. Although C. flaccidum has been placed in Hormoseras Kuetzing 1841 (as H. flaccidum Harvey ex Kuetzing 1862), the type species of Hormoceras is Ceramium diaphanum. The new genus is characterized by alternate branching, incomplete cortication, production of three cortical filament initials of which the basipetal initial divides horizontally, and unicellular rhizoids terminating in pad-like structures produced from periaxial cells. Cortical filament development is discussed for related genera in the tribe Ceramieae (Campylaephora, Carpoblepharis, Centroceras, Ceramium, Corallophila, Herpochondria, Microcladia, Reinboldiella). RbcL-based phylogenies indicate that the new genus is sister to Centroceras, a genus possessing three cortical filament initials. The phylogenetic relationships within the tribe may correlate with cortication patterns that characterize each genus
-
Ceramium INKYUII SP. NOV. (CERAMIACEAE, RHODOPHYTA) FROM KOREA: A NEW SPECIES BASED ON MORPHOLOGICAL AND MOLECULAR EVIDENCE1
Journal of Phycology, 2003Co-Authors: Tae Oh Cho, Suzanne Fredericq, Sung-min BooAbstract:Ceramium inkyuii sp. nov. is newly described based on samples collected from the east coast of Korea and compared with similar species such as C. paniculatum and C. tenerrimum. The new species is characterized by pseudo-dichotomously branched thalli with a twist in the upper part, a single row of spines on the abaxial side, strongly inrolled apices, and the presence of gland cells. In contrast, C. paniculatum has alternate branches and lacks gland cells, and C. tenerrimum is spineless and also lacks gland cells. Ceramium inkyuii was observed to be an annual species producing tetrasporangia in the spring to summer and cystocarps in the fall. Plastid-encoded rbcL and nuclear small subunit (SSU) rDNA sequences were determined in four samples of C. inkyuii from different locations and six samples of four putative relatives. All four C. inkyuii replicates from three different locations had identical sequences of each gene, and the interspecific sequence divergences were enough to warrant its natural entity. The phylogenies of the rbcL and SSU rDNA sequences also indicate the monophyly of C. inkyuii. The spinous C. inkyuii was more closely related to the spineless C. tenerrimum than to the spinous C. paniculatum.