首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Recent molecular analyses of Dictyosphaerium strains revealed a polyphyletic origin of this morphotype within the Chlorellaceae. The type species Dictyosphaerium ehrenbergianum Nägeli formed an independent lineage within the Parachlorella clade, assigning the genus to this clade. Our study focused on three different Dictyosphaerium species to resolve the phylogenetic position of remaining species. We used combined analyses of morphology; molecular data based on SSU and internally transcribed spacer region (ITS) rRNA sequences; and the comparison of the secondary structure of the SSU, ITS‐1, and ITS‐2 for species and generic delineation. The phylogenetic analyses revealed two lineages without generic assignment and two distinct clades of Dictyosphaerium‐like strains within the Parachlorella clade. One clade comprises the lineages with the epitype strain of D. ehrenbergianum Nägeli and two additional lineages that are described as new species (Dictyosphaerium libertatis sp. nov. and Dictyosphaerium lacustre sp. nov.). An emendation of the genus Dictyosphaerium is proposed. The second clade comprises the species Dictyosphaerium sphagnale Hindák and Dictyosphaerium pulchellum H. C. Wood. On the basis of phylogenetic analyses, complementary base changes, and morphology, we describe Mucidosphaerium gen. nov with the four species Mucidosphaerium sphagnale comb. nov., Mucidosphaerium pulchellum comb. nov., Mucidosphaerium palustre sp. nov., and Mucidosphaerium planctonicum sp. nov.  相似文献   

2.
We investigated the similarity of a single Euglena myxocylindracea strain, isolated originally by Bold and MacEntee, to several Euglena geniculata strains on both morphological and DNA levels. We found the three DNA stretches, consisting of fragments coding for the parts of cytoplasmic and chloroplast small subunit rRNA, and the internal transcribed spacer (ITS2) of cytoplasmic rDNA, with the combined length of 4332 nucleotides, are identical in E. myxocylindracea and E. geniculata, strain SAG 1224‐4b. Morphological differences between E. myxocylindracea and any E. geniculata strain examined were well within the range of E. geniculata variability as well. The only difference behind the distinction of E. myxocylindracea from E. geniculata is the presence of the second chloroplast in the latter. However, we were able to induce the appearance of the second chloroplast in the cells of E. myxocylindracea and its disappearance in the cells of E. geniculata by changing the composition of the culture media. We therefore conclude that E. myxocylindracea Bold and MacEntee should be regarded as an environmental form of E. geniculata Dujardin. For the first time the morphology of E. geniculata chloroplasts was shown as revealed by confocal laser microscopy.  相似文献   

3.
The morphology of strains of Skeletonema Greville emend Sarno et Zingone was examined in LM, TEM, and SEM and compared with sequence data from nuclear small subunit rDNA and partial large subunit rDNA. Eight distinct entities were identified, of which four were known: S. menzelii Guillard, Carpenter et Reimann; S. pseudocostatum Medlin emend. Zingone et Sarno; S. subsalsum (Cleve) Bethge; and S. tropicum Cleve. The other four species were new: S. dohrnii Sarno et Kooistra sp. nov., S. grethae Zingone et Sarno sp. nov., S. japonicum Zingone et Sarno sp. nov., and S. marinoi Sarno et Zingone sp. nov. Skeletonema species fell into four morphologically distinct groups corresponding to four lineages in the small subunit and large subunit trees. Lineage I included S. pseudocostatum, S. tropicum, S. grethae, and S. japonicum. All have external processes of the fultoportulae with narrow tips that connect with those of sibling cells via fork‐, knot‐, or knuckle‐ like junctions. Lineage II included only the solitary species S. menzelii. Lineage III comprised S. dohrnii and S. marinoi. This latter pair have flattened and flared extremities of the processes of the fultoportulae, which interdigitate with those of contiguous valves without forming knots or knuckles. Lineage IV only contained the brackish water species S. subsalsum. Some species also differ in their distribution and seasonal occurrence. These findings challenge the concept of S. costatum as a single cosmopolitan and opportunistic species and calls for reinterpretation of the vast body of research data based on this species.  相似文献   

4.
紫色非硫细菌Rhodocista属一新分离株的鉴定及其系统学研究   总被引:11,自引:2,他引:9  
从污水处理厂分离到一株紫色非硫细菌3-p,该菌株具避光性,能形成孢囊,具片层状光合内膜,在波长798nm处的吸收峰很低,需硫胺素和维生素B12作生长因子。该菌株可以琥珀酸为碳源,最佳生长温度为34℃~41℃,体内未发现R体结构,醌类的主要成分是Q-9。对菌株3-p的16S rRNA基因的分子系统学分析结果表明,菌株3-p与世纪红蒌菌(Rhodocista centenaria)关系最近,相似性为9  相似文献   

5.
The diversity of eukaryotic microorganisms is far from fully described, as indicated by the vast number of unassigned genotypes retrieved by environmental sequencing or metagenomics. We isolated several strains of unicellular green algae from algal biofilms growing on tree bark in a Southeast Asian tropical rainforest and determined them to be relatives of an unidentified lineage of environmental 18S rDNA sequences, thus uncovering its cellular identity. Light, confocal, and electron microscope observations and sequencing the 18S rRNA gene revealed that the strains represent two different species within an apparently new genus, described here as Jenufa gen. nov. Both species formed minute coccoid cells with an irregular globular outline, a smooth cell wall, and a single parietal chloroplast without a pyrenoid. The two species, described herein as J. perforata and J. minuta, differed in chloroplast morphology and cell wall structure. Phylogenetic analyses of 18S rRNA gene sequences showed a firm relationship between the two species and placed the Jenufa lineage in an unresolved position within the CS clade (Chlamydomonadales + Sphaeropleales) of the class Chlorophyceae, although possible affinities to the genus Golenkinia were suggested both by maximum‐likelihood (ML) and Bayesian methods. Furthermore, two almost identical environmental 18S rDNA sequences from an endolithic microbial community occurring in dolomite rock in the central Alps turned out to be specifically related to, yet apparently distinct from, the sequence of J. minuta, indicating the existence of an undescribed Jenufa species occurring in the temperate zone.  相似文献   

6.
一个甲烷杆菌新种的描述和系统分类学研究   总被引:10,自引:0,他引:10  
从清华大学环境科学系处理北京啤酒厂污水的厌氧消化器中分离到一株产甲烷菌菌株Px1。其菌体形态为弯曲杆状 ,淡黄色菌落 ,只利用H2 +CO2 产生甲烷。通过生理、形态、结构特征与 1 6SrDNA序列的同源性分析 ,表明菌株Px1是甲烷杆菌属中一个与其它成员不同的新种 ,命名为弯曲甲烷杆菌 (Methanobacteriumcurvumsp .nov .)。  相似文献   

7.
The taxonomic position of Blastodinium navicula Chatton and B. contortum Chatton, parasites of marine copepods, was investigated on the basis of morphological observations and molecular data. The life cycle of Blastodinium includes a parasitic stage, a trophont, and free‐swimming dinospores. The individual cells in the trophont, as well as the dinospores that they produced, were thecate. Dinospores of B. contortum and Bnavicula had peridinioid plate tabulation formula, demonstrating an affiliation to the order Peridiniales Heackel (subdivision Dinokaryota Fensome et al.). This systematic position is in contrast to current classifications, in which the order Blastodiniales Chatton is thought to represent an early evolutionary branch of the dinokaryote lineage. Small‐subunit rRNA gene sequences were generated from six Blastodinium individuals isolated from three different host species. In phylogenetic analyses based on SSU rRNA genes, Blastodinium spp. branched with the typical dinoflagellates. Even though overall statistical support was low, the analyses suggested that Blastodinium spp. are late‐branching, dinokaryote dinoflagellates. Species currently included in Blastodiniales are all parasites, but they are morphologically and functionally diverse. Emerging molecular data also reveal high genetic diversity, and therefore, the taxonomy of the group requires reevaluation.  相似文献   

8.
Species currently classified within the cyanobacterial genus Microcoleus were determined to fall into two distinct clades in a 16S rDNA phylogeny, one containing taxa within the Oscillatoriaceae, the other containing taxa within the Phormidiaceae. The two lineages were confirmed in an analysis of the 16S–23S internal transcribed spacer (ITS) region sequences and secondary structures. The type species for Microcoleus is M. vaginatus Gomont, and this taxon belongs in the Oscillatoriaceae. Consequently, Microcoleus taxa in the Phormidiaceae must be placed in separate genera, and we propose the new genus Coleofasciculus to contain marine taxa currently placed in Microcoleus. The type species for Coleofasciculus is the well‐studied and widespread marine mat‐forming species Microcoleus chthonoplastes (Mert.) Zanardini ex Gomont. Other characters separating the two families include type of cell division and thylakoid structure.  相似文献   

9.
The genus Peridinium Ehrenb. comprises a group of highly diversified dinoflagellates. Their morphological taxonomy has been established over the last century. Here, we examined relationships within the genus Peridinium, including Peridinium bipes F. Stein sensu lato, based on a molecular phylogeny derived from nuclear rDNA sequences. Extensive rDNA analyses of nine selected Peridinium species showed that intraspecies genetic variation was considerably low, but interspecies genetic divergence was high (>1.5% dissimilarity in the nearly complete 18S sequence; >4.4% in the 28S rDNA D1/D2). The 18S and 28S rDNA Bayesian tree topologies showed that Peridinium species grouped according to their taxonomic positions and certain morphological characters (e.g., epithecal plate formula). Of these groups, the quinquecorne group (plate formula of 3′, 2a, 7″) diverged first, followed by the umbonatum group (4′, 2a, 7″) and polonicum group (4′, 1a, 7″). Peridinium species with a plate formula of 4′, 3a, 7″ diverged last. Thus, 18S and 28S rDNA D1/D2 sequences are informative about relationships among Peridinium species. Statistical analyses revealed that the 28S rDNA D1/D2 region had a significantly higher genetic divergence than the 18S rDNA region, suggesting that the former as DNA markers may be more suitable for sequence‐based delimitation of Peridinium. The rDNA sequences had sufficient discriminative power to separate P. bipes f. occultaum (Er. Lindem.) M. Lefèvre and P. bipes f. globosum Er. Lindem. into two distinct species, even though these taxa are morphologically only marginally discriminated by spines on antapical plates and the shape of red bodies during the generation of cysts. Our results suggest that 28S rDNA can be used for all Peridinium species to make species‐level taxonomic distinctions, allowing improved taxonomic classification of Peridinium.  相似文献   

10.
A new filamentous cyanobacterial species of the genus Brasilonema was isolated from the island of Oahu, Hawaii. The taxon is distinguished from the seven other species in the genus by attenuation of trichomes, and is here described as Brasilonema angustatum sp. nov. It possesses the cytoplasmic kerotimization and reddish‐brown coloration of several species in the genus. Phylogenetic analysis based on 16S rRNA gene sequence shows B. angustatum within a highly supported clade containing all sequenced Brasilonema species. We compared the secondary structure of the 16S–23S ITS regions for B. octagenarum and B. angustatum. The structurally conservative D1–D1′ and V3 helices show similar motifs between the two taxa, but differ structurally and in sequence, providing additional justification for erection of the new species. The Box‐B helix has identical secondary structure. The existence of tapering in a Brasilonema species is unique in this genus, and requires modification of the current concept of the genus Brasilonema, which was described as being unattenuated. Our phylogenetic evidence supports the hypothesis that tapering has developed repeatedly in separate cyanobacterial lineages and lacks the taxonomic significance once assumed by early workers.  相似文献   

11.
对中国柯坚甲属Colobicus进行了分类整理,发现1新种,常卿柯坚甲C.changqingi sp.nov..提供了中国已知种检索表和形态特征图.模式标本保存在河北大学博物馆.常卿柯坚甲,新种Colobicus changqingi sp.nov.(图12 ~ 28)新种与分布于台湾的沥青柯坚甲Colobicu parilis Pascoe,1860在外形上相似,两者的主要区别是:1)前者头部近似梯形,前胸背板宽大,而后者头部近似三角形,前胸背板窄小;2)前者鞘翅具黄色毛簇,后者则无;3)前者鞘翅刻点行不明显,后者明显9列;4)前者的前胸腹突宽大,顶部直截,无中纵沟,而后者的前胸腹突短,顶圆,有中纵沟和粗糙刻点;5)前者腹部基节中突的前缘稍尖,钝角形,而后者的前缘直.正模♂,台湾屏东狮子乡,2009-05-30,周文一采.词源:新种种名源自标本馈赠人陈常卿先生的名字.  相似文献   

12.
叶明  庄文颖 《菌物学报》2002,21(3):340-345
粒毛盘菌属包括晶杯菌科中子囊盘表面具有毛状物,毛状物全表面具有颗粒状纹饰以及外囊盘被结构为矩胞组织的部分种类,种间形态解剖结构多样,研究采用ITS15.8S rDNAITS2序列分析的方法探讨该属种间的系统发育关系。在供试的粒毛盘菌15个分类单元中,14个以89%的支持强度值相聚在一起,其中Lachnum clandestinum与 L. fuscescens关系最近,其支持强度值为100%;其次为L. controversum 与L. spartinae,其支持强度值为97%;而姊妹群L. euterpes,L. pteridophyllum,L. singerianum和L. lushanense彼此关系较远,其支持强度值均小于50%;L. sclerotii位于系统发育树的最外侧,为供试15个分类单元中距离最远的一个,结果表明粒毛盘菌属可能是多起源的。  相似文献   

13.
2002年从中国山东省乳山市大画眉草Eragrostis cilianensis的根际土壤中发现滑刃属1新种盘尾滑刃线虫Aphelenchoides disccaudatus sp.nov.。雌虫具有以下特征:虫体小,侧线3条;唇区较高,缢缩明显;尾钩状,末端具平盘状尾尖突。雄虫未见。  相似文献   

14.
糖单孢菌16S rDNA的PCR-RFLP分析   总被引:5,自引:0,他引:5  
PCR-RFLP分析适用于种和种间水平的多相分类研究。文章对PCR-RFLP方法应用于糖单孢菌属分类有具体方法进行了探讨;报道了一组适于糖单孢菌属PCR-PFLP分析的限制性内切酶,并用这组酶对6株糖单孢菌属分离株进行了研究,进一步探讨了实验菌株在该属的分类地位。同时指出了PCR-RFLP方法应用中应注意的问题。  相似文献   

15.
酣弄蝶属Halpe全世界已知48种,中国已知16种,在总结中国酣弄蝶分类研究的基础上,记述1新种:凹斑酣弄蝶Halpe concavimarginata sp.nov.,制作了中国酣弄蝶属分种检索表。模式标本保存于西北农林科技大学昆虫博物馆。 凹斑酣弄蝶,新种Halpe concavimarginata sp.nov.(图1 ~5) 新种外形与峨眉酣弄蝶Halpe nephele Leech,1893非常近似,主要区别是:新种前翅长18~20mm;前翅中域斑的外缘向内凹入;前后翅的缘毛黑白相间非常明显;抱器端2分瓣间的“U”形凹陷跨度较小,凹陷底部无锯齿。峨眉酣弄蝶Halpe nephele Leech前翅长17.5~18.0mm;前翅中域斑的外缘直,不凹入;前后翅的缘毛黑白相间不明显;抱器端两分瓣间“U”形凹陷跨度大,锯齿连续。 新种也近似白缘毛酣弄蝶Halpe albicilia Tsukiyama et Chiba,1991 ,区别在于白缘毛酣弄蝶前翅长21mm,后翅的缘毛全白色,外生殖器也不同。 模式标本正模♂,副模1 ♂,四川芦山, 1996 ,汪炳红采。  相似文献   

16.
A new potentially ichthyotoxic dinoflagellate genus, Takayama de Salas, Bolch, Botes et Hallegraeff gen. nov., is described with two new species isolated from Tasmanian (Australia) and South African coastal waters: T. tasmanica de Salas, Bolch et Hallegraeff, sp. nov. and T. helix, de Salas, Bolch, Botes et Hallegraeff, sp. nov. The genus and two species are characterized by LM and EM of field samples and laboratory cultures as well as large subunit rDNA sequences and HPLC pigment analyses of several cultured strains. The new Takayama species have sigmoid apical grooves and contain fucoxanthin and its derivatives as the main accessory pigments. Takayama tasmanica is similar to the previously described species Gymnodinium pulchellum Larsen, Gyrodinium acrotrochum Larsen, and G. cladochroma Larsen in its external morphology but differs from these in having two ventral pores, a large horseshoe‐shaped nucleus, and a central pyrenoid with radiating chloroplasts that pass through the nucleus. It contains gyroxanthin‐diester and a gyroxanthin‐like accessory pigment, both of which are missing in T. helix. Takayama helix has an apical groove that is nearly straight while still being clearly inflected. A ventral pore or slit is present. It has numerous peripheral, strap shaped, and spiraling chloroplasts with individual pyrenoids and a solid ellipsoidal nucleus. The genus Takayama has close affinities to the genera Karenia and Karlodinium.  相似文献   

17.
18.
Twelve populations of filamentous, heterocytous scytonematoid cyanobacteria from subaerophytic (mainly epiphytic) habitats in subtropical and tropical Brazil (São Paulo) were studied. The populations form a uniform cluster, which differs from the traditional scytonematoid genera genetically and by several indistinct, but typical morphological characters (fasciculation of filaments, rare false branching). Two strains were isolated in monospecific cultures. Molecular analyses were performed on these strains from natural populations taken from bromeliad leaves and iron water pipes. Because the results from 16S rRNA gene sequencing indicated the separate position of this cyanobacterium at the generic level, a new genus, Brasilonema, is proposed with the type species Brasilonema bromeliae. The new genus is described using combined molecular and cytomorphological criteria, in accordance with the nomenclatorial recommendations of both the Bacteriological Code and the Botanical Code of Nomenclature (cf. Oren 2004 ). The ultrastructure of the type species was studied, and vacuole‐like structures in the cells were explained. The genus Brasilonema is commonly distributed, particularly in subaerophytic habitats from southeastern Brazil. The type species (B. bromeliae) has a rather curious ecology, living epiphytically (in phytothelmes) inside the vase‐shaped leaf rosettes of bromeliads.  相似文献   

19.
An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species of Karlodinium (K. micrum (Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic of Karlodinium. In K. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile of K. armiger revealed the presence of chlorophylls a and c, with fucoxanthin as the major carotenoid. Phylogenetic analysis confirmed K. armiger to be related to other species of Karlodinium; thus forming a monophyletic genus, which, in the LSU tree, occupies a sister group position to Takayama de Salas, Bolch, Botes et Hallegraeff. The culture used by Ballantine to describe Gymnodinium veneficum Ballantine (Plymouth 103) was examined by light and electron microscopy and by partial LSU rDNA. Ultrastructurally, it proved identical to K. micrum (cultures Plymouth 207 and K. Tangen KT‐77D, the latter also known as K‐0522), and in LSU sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species, K. micrum, to K. veneficum. The three genera Karlodinium, Takayama, and Karenia constitute a separate evolutionary lineage, for which the new family Kareniaceae fam. nov. is suggested.  相似文献   

20.
Skeletonema costatum (Grev.) Cleve emend. Zingone et Sarno and S. grevillei Sarno et Zingone were known only from the type material collected from Hong Kong waters more than a century ago. Both species have now been collected as live material, and their morphology and phylogenetic position are investigated in this study. Eight Skeletonema strains isolated from Florida, USA; Uruguay; and Brazil are attributed to S. costatum, while one strain from Oman is ascribed to S. grevillei based on morphological similarity to the type material of these species. In addition, a new Skeletonema species, S. ardens Sarno et Zingone, is described for a strain from Singapore and two from northern Australian waters. Skeletonema ardens has terminal fultoportula processes ending in a tapered, undulate protrusion and long intercalary fultoportulae with 1:1 junctions. The rimoportula of terminal valves is located at the margin of the valve face. No major morphological variations were observed within S. grevillei and S. ardens along a salinity gradient, whereas in S. costatum, the processes shortened and the valves came into close contact at low salinities, as already described for S. subsalsum (Cleve) Bethge. Consistent with their morphology, Skeletonema costatum and Skeletonema subsalsum also had similar rDNA sequences. Skeletonema grevillei and S. ardens were distinct in the large subunit (LSU) phylogeny. Skeletonema ardens exhibited consistent intraspecific genetic differences in both the LSU and small subunit (SSU) rDNA.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号