利用整合分类学方法进行蕨类植物复合体的物种划分: 以线裂铁角蕨复合体为例

广泛的杂交和多倍化使得铁角蕨属(Asplenium)下存在着许多分类困难的物种复合体, 针对这些类群进行整合分类学的研究, 有助于我们更加全面和深入地理解物种的界限以及形成机制。线裂铁角蕨复合体(Asplenium coenobiale complex)是铁角蕨属下一个形态多样性较高的类群, 由于缺乏全面取样和系统研究, 该复合体的物种划分长期存在争议。本研究选取线裂铁角蕨复合体中形态变异和地理分布具有代表性的个体, 通过孢粉学研究确定该类群的生殖特性, 运用流式细胞分析获取倍性信息, 同时结合叶绿体和核基因组片段系统发生分析的证据, 对该类群的系统演化关系和起源方式进行了探讨。结果表明: (1)虽然部分孢子囊败育的情况在线裂铁角蕨复合体中十分普遍, 但正常孢子囊内形成的64个孢子说明该类群植物仍能进行正常的有性生殖; (2)该复合体中存在着倍性变异, 其中多角铁角蕨(A. cornutissimum)是二倍体, 而其他成员均为四倍体; (3)依据母系遗传的叶绿体序列所构建的系统发生关系将该类群划为4个分支, 与基于核基因序列构建的系统树存在冲突, 这暗示杂交可能在该复合体的形成过程中起到了重要的推动作用。综上所述, 我们建议将线裂铁角蕨复合体划分为4个物种, 即同源四倍体新种马关铁角蕨(A. maguanense sp. nov.), 二倍体多角铁角蕨, 以及两个由同一对亲本正反交产生的异源四倍体线裂铁角蕨(A. coenobiale)和叶基宽铁角蕨(A. pulcherrimum)。     

Phylogeny and taxonomy of Afrocayratia,a new genus of Vitaceae from continental Africa and Madagascar

The genus Cayratia Juss. in the traditional sense (i.e., Cayratia s.l.) of the grape family has been shown to be non‐monophyletic. Previous studies supported the splitting of Cayratia s.l. into three genera, that is, Cayratia s.s., Causonis Raf., and a new genus representing the African Cayratia clade. However, the morphology of the African Cayratia clade has not been studied carefully and its phylogenetic position within Vitaceae remains unclear. Our study integrates molecular, distributional, and morphological data and supports the recognition of the new genus Afrocayratia from continental Africa and Madagascar. Phylogenetic analyses strongly support the monophyly of Afrocayratia and resolve it as a sister of Cayratia s.s. based on the chloroplast data, but it is placed sister to Cyphostemma based on the internal transcribed spacer dataset. Molecular dating suggests that Afrocayratia split with Cayratia s.s. during the Paleocene, but that the extant species of Afrocayratia did not diversify until the early Miocene. Afrocayratia differs from its allied genera in having short stigmas and seeds with subcircular ventral infold cavities in cross‐section. Three clades are detected within Afrocayratia, with A. debilis (Baker) J.Wen & L.M.Lu as the first diverged lineage. The second diverged lineage includes A. delicatula (Willems) J.Wen & Z.D.Chen and A. gracilis (Guill. & Perr.) J.Wen & Z.D.Chen. The third diverged lineage includes A. imerinensis (Baker) J.Wen & L.M.Lu, A. longiflora (Desc.) J.Wen & Rabarijaona, and A. triternata (Baker) J.Wen & Rabarijaona from Madagascar, which form a monophyletic group that diverged from the second lineage in the middle Miocene. Combining the morphological and molecular evidence, we formally describe the new genus Afrocayratia, make seven new combinations, and provide a key to species of the genus.     

高茎紫菀(菊科)形态描述补充及细胞学和分子系统学研究北大核心CSCD

结合在模式产地采集的高茎紫菀(Aster procerus Hemsley)以及查阅文献资料,发现原始文献对其形态描述不充分且缺乏细胞学和分子系统学方面的报道。本研究对高茎紫菀的形态特征进行了补充描述以及核型特征和系统位置分析,为紫菀属的修订提供资料。结果表明:(1)依据观察结果,补充了高茎紫菀新的形态特征:基生叶羽状分裂,成熟的基生叶较大,长可达26 cm,宽可达8 cm;花序托圆锥状。(2)高茎紫菀的染色体数目为2n=18;核型公式为2n=2x=16 m+2 M,核型属于1 A。(3)基于ITS和ETS标记的分子系统发育树分析表明,高茎紫菀不同居群的2个个体在同一进化支上(LP=100,PP=1.00),且位于核心紫菀属(LP=100,PP=1.00),与女菀[Turczaninovia fastigiata(Fischer)Candolle]构成姐妹类群(LP=52,PP=0.99)。研究认为,高茎紫菀基生叶和花序托的特征可为紫菀属的分类提供新的证据,支持高茎紫菀位于紫菀属(Aster L.)内,建议将女菀并入紫菀属。     

Analysis of phylogenetic relationships of Potamogeton species in China based on chloroplast trnT-trnF sequences

Sequences of the chloroplast trnT-trnF region were analyzed for species of the genus Potamogeton distributed in China to reconstruct phylogenetic relationships. The phylogenetic analyses showed that the genus Potamogeton could be divided into two clades. Eighteen species formed a monophyletic clade while the remaining four formed a second, distinguishable one, supporting the conventional treatment that the genus Potamogeton contains the submerged linear-leaved group and the submerged broad-leaved group. The first clade, which represented the subgenus Potamogeton, could be further divided into two subclades. The second clade, which represented the subgenus Coleogeton, displayed a close phylogenetic relationship with the subgenus Potamogeton and occupied a unique position within the genus Potamogeton. This finding suggested that the treatment of the subgenus Coleogeton, which was once regarded as the genus Stuckenia Börner, may need to be reconsidered. Furthermore, identification of maternal donors of some hybrids was successfully applied based on sequence of maternally inherited chloroplast genome. The female parents of three putative hybrids, P. × malainoides, P. × anguillanus, and P. × orientalis, were proved to be accordant with previous morphological conclusions.     

Alexandrium catenella and Alexandrium minutum blooms in the Mediterranean Sea: Toward the identification of ecological niches

Annual recurrent blooms of the toxic dinoflagellates Alexandrium catenella and Alexandrium minutum were detected from 2000 to 2003 in harbours along the Catalan coast. The interrelation study between the occurrence of the blooms and specific external conditions at the study sites demonstrated that different factors are required for the bloom of each Alexandrium species. Concentrations higher than 10⁵ cells l⁻¹ of A. catenella were only detected in Tarragona harbour. These blooms were associated with water surface temperature between 21 and 25 °C and salinities of around 34 psu or higher than 37 psu. A. minutum appeared widely spread along the Catalan coast, though the most intensive and recurrent blooms of this species were observed in Arenys de Mar harbour. Concentrations of millions of cells per litre of A. minutum were associated with water temperatures below 14 °C and salinities of around 34–36 psu. A. minutum cell densities showed a positive significant correlation with NO₃ but a negative correlation with NH₄. On the other hand, A. catenella blooms dominated when both NO₃ and NH₄ levels were high. The prevailing inorganic nitrogen form (NO₃ vs. NH₄) could explain why these two species rarely coincide in the same harbours. Accumulation of cysts in the sediment was found to be an important potential factor for the recurrence of these species. The 4.3 × 10³ A. catenella cysts cm⁻³ of wet sediment in Tarragona harbour and the 3.02 × 10³ A. minutum cysts cm⁻³ of wet sediment in Vilanova harbour were the highest concentrations observed from the cyst study. Confined waters such as harbours play an important role as reservoirs for the accumulation of cysts and vegetative cells, which contributes to the expansion of these dinoflagellates in the region. However, the particular environmental conditions are also decisive factors of bloom intensity.     

Brown tide alga, Aureococcus anophagefferens, can affect growth but not survivorship of Mercenaria mercenaria larvae

Since the collapse of populations of northern quahogs (hard clam), Mercenaria mercenaria, in Long Island bays, brown tide blooms have been proposed to pose a barrier to recovery. We tested whether the brown tide alga, Aureococcus anophagefferens, affects survivorship, development or growth in the larvae of M. mercenaria. There was no effect of A. anophagefferens (clone CCMP1708) on survivorship of hard clam larvae, even at bloom concentrations. Under most experimental conditions, larvae fed a mixed diet of Isochrysis galbana (T-Iso) and A. anophagefferens or a single species diet of A. anophagefferens, developed faster than those fed a single species diet of Isochrysis. A mixed diet of I. galbana and A. anophagefferens either had no effect on larval growth, or produced enhanced growth at moderate cell densities (8 × 10⁴ cells ml⁻¹ of A. anophagefferens). Similarly, moderate cell densities of a single food diet of A. anophagefferens (1.6 × 10⁵ cells ml⁻¹) generally had no effect on the growth of larvae. When fed bloom concentrations (10⁶ cells ml⁻¹) of A. anophagefferens, larvae developed faster, but growth was reduced, compared to those fed an equal biovolume of Isochrysis. Larvae fed slow growing or near stationary phase cultures of A. anophagefferens experienced reduced growth and slowed development. These data suggest a qualitative difference between slow or stationary phase and fast growing cultures of the brown tide alga. They also suggest that impacts of A. anophagefferens, when present, are likely to be due to the nutritional quality of this alga as a food source for hard clam larvae, which could have a lasting legacy through ontogeny. Additional studies are needed to test whether our findings apply to more recently isolated strains of A. anophagefferens.     

Phylogeny and infrageneric classification of Symplocos (Symplocaceae) inferred from DNA sequence data

Symplocos comprises ～300 species of woody flowering plants with a disjunct distribution between the warm-temperate to tropical regions of eastern Asia and the Americas. Phylogenetic analyses of 111 species of Symplocos based on the nuclear ribosomal internal transcribed spacer (ITS) region and the chloroplast genes rpl16, matK, and trnL-trnF yielded topologies in which only one of the four traditionally recognized subgenera (Epigenia; Neotropics) is monophyletic. Section Cordyloblaste (subgenus Symplocos; eastern Asia) is monophyletic and sister to a group comprising all other samples of Symplocos. Section Palura (subgenus Hopea; eastern Asia) is sister to a group comprising all other samples of Symplocos except those of section Cordyloblaste. Symplocos wikstroemiifolia (eastern Asia) and S. tinctoria (southeastern United States), both of subgenus Hopea, form a clade that groups with S. longipes (tropical North America) and the species of subgenus Epigenia. The remaining samples of subgenus Hopea (eastern Asia) form a clade. Section Neosymplocos (subgenus Microsymplocos; Neotropics) is well nested within a clade otherwise comprising the samples of section Symplocastrum (subgenus Symplocos; Neotropics). Section Urbaniocharis (subgenus Microsymplocos; Antilles) groups as sister to the clade comprising Symplocastrum and Neosymplocos. The data support the independent evolution of deciduousness among section Palura and S. tinctoria. The early initial divergence of sections Cordyloblaste and Palura from the main group warrants their recognition at taxonomic levels higher than those at which they are currently placed. An inferred eastern Asian origin for Symplocos with subsequent dispersal to the Americas is consistent with patterns from other phylogenetic studies of eastern Asian-American disjunct plant groups but contrary to a North American origin inferred from the earliest fossil occurrences of the genus.     

A systematic study of North American Angelica species (Apiaceae) based on nrDNA ITS and cpDNA sequences and fruit morphology

Angelica is a taxonomically complex genus widespread throughout the North Temperate Zone. Previous phylogenetic studies of the genus have focused primarily on its East Asian species. The relationships among its North American members, the monophyly of these species, and the value of fruit morphology in circumscribing its taxa have yet to be examined. This study represents the most comprehensive sampling of Angelica to date (100 species) and includes all 26 species in North America. Relationships are inferred using Bayesian inference, maximum likelihood, and maximum parsimony analyses of ITS sequences and, for multiple accessions of each North American species, cpDNA ndhF-rpl32, rpl32-trnL, and psbM-psbD sequences. The fruit morphological characters examined were those considered phylogenetically important in East Asian Angelica. The results revealed that the North American species fell into three major clades: North American Angelica clade, Archangelica clade, and the Eurasian Angelica clade. Angelica dawsonii has affinities with Lomatium brandegeei. Fourteen species within the North American Angelica clade were strongly supported as monophyletic. Two paraphyletic species resulted in new combinations in A. lineariloba and A. venenosa. Conflict between the ITS-derived and cpDNA-derived phylogenies and the lack of resolution in portions of the trees may be due to chloroplast capture and rapid species radiation. Fruit morphology supported some interspecific relationships based on molecular data, and relationships revealed by ITS and cpDNA data were roughly in accordance with fruit classification type and geographic distribution region, respectively. A diagnostic key based on fruit morphology is provided for the identification of the North American Angelica taxa.     

Global chloroplast phylogeny and biogeography of bracken (Pteridium; Dennstaedtiaceae)

Bracken ferns (genus Pteridium) represent an ancient species complex with a natural worldwide distribution. Pteridium has historically been treated as comprising a single species, but recent treatments have recognized several related species. Phenotypic plasticity, geographically structured morphological variation, and geographically biased sampling have all contributed to taxonomic confusion in the genus. We sampled bracken specimens worldwide and used variable regions of the chloroplast genome to investigate phylogeography and reticulate evolution within the genus. Our results distinguish two major clades within Pteridium, a primarily northern hemisphere Laurasian/African clade, which includes all taxa currently assigned to P. aquilinum, and a primarily southern hemisphere Austral/South American clade, which includes P. esculentum and P. arachnoideum. All European accessions of P. aquilinum subsp. aquilinum appear in a monophyletic group and are nested within a clade containing the African P. aquilinum taxa (P. aquilinum subsp. capense and P. aquilinum subsp. centrali-africanum). Our results allow us to hypothesize the maternal progenitors of two allotetraploid bracken species, P. caudatum and P. semihastatum. We also discuss the biogeography of bracken in the context of the chloroplast phylogeny. Our study is one of the first to take a worldwide perspective in addressing variation in a broadly distributed species complex.     

Lack of effect of the nematophagous fungus Duddingtonia flagrans on the development of the dung beetle, Aphodius constans

The nematode-trapping fungus Duddingtonia flagrans may be used as a biological control agent of gastro-intestinal nematode larvae of ruminants by feeding the hosts with fungal spores. This trial was intended to search an eventual detrimental impact of the presence of spores of D. flagrans in high numbers in goat feces on the common dung beetle, Aphodius constans (Coleoptera: Aphodiidae). A. constans eggs were settled in feces derived from grazing goats fed spores at daily dose rates of 0, 0.25 × 10⁶, 0.5 × 10⁶ or 10⁶ spores/kg BW. At the end of the incubation period, the number of adults that have emerged from eggs were counted and compared between dose rates. No difference in emergence rate between treatments can be seen. The presence of D. flagrans spores in goat feces, even in large numbers, did not alter the development of A. constans.     

Subunit polypeptide composition of rubisco and the origin of allopolyploid Arabidopsis suecica (Brassicaceae)

The polypeptide composition of the large and small subunits of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) from Arabidopsis thaliana, A. suecica and Cardaminopsis arenosa have been studied by IEF (isoelectric focusing) analysis. The putative recent alopolyploid origin of A. suecica is supported. The chloroplast encoded large subunits served to identify solely A. thaliana as the maternal parent whereas the nuclear encoded small subunits indicate C. arenosa as the paternal species.     

中国薄叶卷柏复合群的物种划分

卷柏属(Selaginella)是石松类植物中最大的属, 也是分类难度较大的类群之一。该属的物种划分主要基于形态特征, 但许多近缘种在形态上很难区分。近年来, 已有大量分子证据被用于各植物类群的分类学研究, 但目前未发现一套适合卷柏属物种鉴定的分子标记。薄叶卷柏复合群(S. delicatula group)是卷柏属下鉴定较为困难的类群, 包括了薄叶卷柏(S. delicatula)、黑顶卷柏(S. picta)和瓦氏卷柏(S. wallichii) 3个物种, 主要分布于亚洲的热带和亚热带地区。为了探讨薄叶卷柏复合群内物种的亲缘关系和评估不同分子标记在卷柏属分类学研究中的应用价值, 本研究对该复合群物种进行广泛取样, 共收集到73个个体, 并选取3个叶绿体基因(rbcL, psbA和atpI)和2个核基因(26S nrDNA和pgiC)片段进行系统树的构建及叶绿体单倍型分析。研究发现, 基于叶绿体和核基因构建的系统发生关系存在冲突: 叶绿体基因树上薄叶卷柏个体分为两个分支(A和B), 薄叶卷柏B分支与薄叶卷柏A-S. picta分支呈姐妹关系, 并且rbcL单倍型分析结果也表明薄叶卷柏A和B两个分支存在明显分化; 而核基因结果则支持该复合群3个物种各自的单系性, 其中, S. delicatula分支与S. picta分支为姐妹群, S. wallichii与S. delicatula-S. picta分支为姐妹关系。在对复合群分布区大量标本的观察以及野外群体调查的基础上, 评估了植株茎和枝的分枝方式、孢子叶、营养叶(侧叶、中叶和腋叶)和孢子表面纹饰等形态性状的分类学价值。结果表明, 薄叶卷柏A和B分支的样本仅在植株分枝方式和大孢子表面纹饰上存在差异, 但无法依靠小孢子表面纹饰、孢子叶穗和营养叶形态等特征进行区分。基于现有证据, 薄叶卷柏复合群至少可划分为薄叶卷柏、黑顶卷柏和瓦氏卷柏3种, 但彻底澄清该复合群的物种划分还需要获取模式标本产地的材料和细胞学证据。最后, 建议在未来卷柏属的分类学研究集中于该属分类复杂的复合群, 结合使用形态学、细胞学、分子生物学(同时使用核基因和叶绿体分子标记)及地理分布等整合证据来进行物种划分。     

Evolution of the Eastern Asian and Eastern North American disjunct genus Symplocarpus (Araceae): insights from chloroplast DNA restriction site data

Chloroplast DNA (cpDNA) variation was surveyed with 20 restriction endonucleases for the eastern Asian and eastern North American disjunct genus Symplocarpus (Araceae). The cpDNA phylogeny reveals a sister group relationship between S. foetidus from eastern North America and S. renifolius from eastern Asia. The cpDNA divergence between the two intercontinental sister species is 0.61%, which suggests an estimated divergence time of 6.1 million years ago during the late Miocene. The Bering land bridge hypothesis is compatible with the estimated time of divergence for the migration of Symplocarpus between eastern Asia and North America. Furthermore, a single origin of the exothermic spadices in Symplocarpus is suggested by the phylogeny. The cpDNA data also provide independent support for the recognition of three species within the genus.     

Antechiniscus in Australia: Description of Antechiniscus moscali sp. n. and Redescription of Antechiniscus parvisentus (Horning & Schuster, 1983) (Heterotardigrada: Echiniscidae)

Two species of the genus Antechiniscus have been found in Nothofagus forests in Australia. The new species A. moscali sp. n. is described. The New Zealand species A. parvisentus (Horning & Schuster, 1983) is redescribed from type material and from the new material from Australia. The taxonomic status of the two species within the genus is discussed.     

Loss of Symbiodinium from bleached soft corals Sarcophyton ehrenbergi, Sinularia sp. and Xenia sp.

The deleterious effects of temperature-induced coral bleaching, a process by which corals lose their endosymbiotic algae (zooxanthellae; genus Symbiodinium) primarily at temperatures above mean yearly maximums, has not been well described for alcyonacean soft corals (Coelenterata, Octocorallia). The study of Symbiodinium cells lost from Sarcophyton ehrenbergi, Sinularia sp., and Xenia sp., which have not been compared in bleaching studies, indicate that the soft coral S. ehrenbergi released the greatest number of symbiont cells, however, it was less susceptible to heat stress surviving temperatures of 34 °C for >39 h. Sinularia sp. showed intermediate levels of bleaching tolerance to elevated temperatures, surviving prolonged exposures at 32 °C, but dying within 24 h at 34 °C. Xenia sp., however, was the most vulnerable to high heat stress maximally releasing Symbiodinium at temperatures ≤30 °C. This evidence indicates that Xenia sp. is even more susceptible to elevated temperatures than Acropora spp., previously reported to be the most vulnerable coral species to elevated temperature-induced bleaching.

Molecular analysis showed that the more resistant soft coral species (S. ehrenbergi) had the same type of Symbiodinium (clade C) as less resistant soft corals (Xenia sp.). In comparison to scleractinian corals collected from the same region that show similar bleaching resistance to high temperatures (e.g. Porities solida—more robust; Favites complanata—moderate resistance; Acropora hyacinthus—less robust), all scleractinian corals were symbiotic with Symbiodinium from clade C. A. hyacinthus, however, was found to possess multiple symbionts (clades B and C), and this represents a first report of Clade B in any Acropora species.     

Experimental hybridization of Angiostrongylus mackerrasae, Bhaibulaya, 1968 and Angiostrongylus cantonensis (Chen, 1935)

Angiostrongylus mackerrasae and A. cantonensis are closely related and their status as distinct species was tested by experimental hybridization. Hybridization between A. mackerrasae and A. cantonensis was observed and the morphology of the F₁ hybrids was found to be intermediate between that of the parental species which suggests strongly that A. mackerrasae and A. cantonensis are both valid species. However, male F₁ hybrids were sterile, whereas females were fertile; no evidence of parthenogenesis or other form of asexual reproduction were observed in either species. It is suggested that A. mackerrasae and A. cantonensis may cross breed in nature.     

The sporadic occurrence of a group I intron-like element in the mtDNA rnl gene of Ophiostoma novo-ulmi subsp. americana

The presence of group I intron-like elements within the U7 region of the mtDNA large ribosomal subunit RNA gene (rnl) was investigated in strains of Ophiostoma novo-ulmi subsp. americana from Canada, Europe and Eurasia, and in selected strains of O. ips, O. minus, O. piceae, O. ulmi, and O. himal-ulmi. This insertion is of interest as it has been linked previously to the generation of plasmid-like mtDNA elements in diseased strains of O. novo-ulmi. Among 197 O. novo-ulmi subsp. americana strains tested, 61 contained a 1.6 kb insertion within the rnl-U7 region and DNA sequence analysis suggests the presence of a group I intron (IA1 type) that encodes a potential double motif LAGLIDADG homing endonuclease-like gene (HEG). Phylogenetic analysis of rnl-U7 intron encoded HEG-like elements supports the view that double motif HEGs originated from a duplication event of a single-motif HEG followed by a fusion event that combined the two copies into one open reading frame (ORF). The data also show that rnl-U7 intron encoded ORFs belong to a clade that includes ORFs inserted into different types of group I introns, e.g. IB, ID, IC3, IA1, present within a variety of different mtDNA genes, such as the small ribosomal subunit RNA gene (rns), apo-cytochrome b gene (cob), NADH dehydrogenase subunit 5 (nad5), cytochrome oxidase subunit 1 gene (coxI), and ATPase subunit 9 gene (atp9).

We also compared the occurrence of the rnl-U7 intron in our collection of 227 strains with the presence of the rnl-U11 group I intron and concluded that the U7 intron appears to be an optional element and the U11 intron is probably essential among the strains tested.     

Ascomycetes on Polytrichadelphus aristatus (Musci)

Fourteen herbarium specimens of Polytrichadelphus aristatus (Polytrichaceae, Musci) from the northern Andes were found to be colonized by ascomycetes. Thirty fungal specimens are indicated representing nine species and six genera. They belong to the first records of bryophilous fungi of northern South America. Five taxa are proposed as new: the genus Aphanotria, and the species A. paradoxa, Bryochiton macrosporus, Bryorella imitans, and Massarina polytrichadelphi. Most frequently found were Rogellia triseptata with six and Bryochiton macrosporus with five records. Four species develop their ascomata between the photosynthetic leaf lamellae, three are immersed within the abaxial side of the leaf nerve and two grow below the adaxial cuticle. The hypocrealean A. paradoxa, which has huge but almost invisible ascomata, merits special attention. Apart from a pronounced rostrum, these are completely immersed within the leaf nerve but longitudinally orientated occupying a type of microniche hitherto unknown. Hyphae of several species attack the thick-walled stereids of the leaf nerve and strongly contribute to leaf decomposition. Polytrichadelphus aristatus has an assemblage of parasitic ascomycetes quite different from that of P. magellanicus from southern South America.     

The Aspergillus niger carbon catabolite repressor encoding gene, creA

In order to undertake a comparative analysis of carbon catabolite repression in two Aspergillus species, the creA gene has been isolated from A. niger by cross hybridization, using the cloned A. nidulans gene. The A. niger gene has been shown to be functional in A. nidulans by heterologous complementation of the creA204 mutation of A. nidulans. Overall, the genes show 90% sequence similarity (82% identity) at the amino acid (aa) level. There were some striking similarities between the aa sequences encoded by the two fungal creA genes and two genes involved in carbon catabolite repression in Saccharomyces cerevisiae. The zinc-finger regions showed 96% similarity (84% identity) with the zinc-finger region of the MIG1 gene of S. cerevisiae. The CREA protein contains a stretch of 42 aa that is identical in A. niger and A. nidulans, and these show 81% similarity (33% identity) with a region of the S. cerevisiae RGR1 gene.     

Molecular phylogeny and taxonomic revision of Chlamydomonas (Chlorophyta). I. Emendation of Chlamydomonas Ehrenberg and Chloromonas Gobi, and description of Oogamochlamys gen. nov. and Lobochlamys gen. nov

The genus Chlamydomonas (including Chloromonas) is one of the largest green algal genera comprising more than 600 species. To initiate a comprehensive analysis of the phylogeny and systematics of the genus, we determined nuclear-encoded SSU rRNA sequences from 32 strains of Chlamydomonas, Chloromonas and Chlorogonium with emphasis on oogamous taxa and related strains, and incorporated these into global molecular phylogenetic analyses of 132 strains of Chlorophyceae. In addition, we studied the morphology and reproduction of oogamous and related strains by light microscopy. We recognize and designate 18 monophyletic lineages (clades) within the Chlorophyceae, 11 of which are confined to the CW (basal bodies displaced clockwise) subgroup. The majority of clades recognized within the Chlorophyceae do not correspond to any of the traditional classification systems, which are still largely based on the organization level. Strains assigned to Chlamydomonas and Chloromonas were found in seven different clades confirming the polyphyly of the two genera as presently conceived. To initiate the taxonomic revision of Chlamydomonas, C. reinhardtii is proposed as the conserved type of the genus. In consequence, species in clades other than the clade containing C. reinhardtii must be transferred to other genera, a process initiated in this contribution. The oogamous strains studied represent a monophyletic lineage, which is described as Oogamochlamys gen. nov. comprising three species (O. gigantea, O. zimbabwiensis and O. ettlii spec. nov.). The sister clade to Oogamochlamys consists of isogamous strains characterized by chloroplasts with incisions and is described as Lobochlamys gen. nov. with two species (L. culleus and L. segnis). Another clade is characterized by asteroid or perforated, parietal chloroplasts and contains the type species of Chloromonas (C. reticulata). Thus, the polyphyletic Chloromonas (traditionally defined as “Chlamydomonas without pyrenoids”) can be legitimized as a monophyletic genus by restriction to this clade and is here emended on the basis of chloroplast characters (the clade contains strains with or without pyrenoids thus rejecting the character “absence of pyrenoids”).