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 15 毫秒
1.
Four related species in the unicellular volvocalean genus Carteria [C. crucifera Pascher, C. eugametos Mitra, C. inversa (Korshikov) Bourrelly and C. cerasiformis Nozaki et al.] were delineated on the basis of recent comparative light and electron microscopy of a large number of culture strains. However, the species thus delineated may not represent natural or monophyletic entities. In the present study, 1128 base pairs of the chloroplast protein-coding gene (large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase gene) from 12 Carteria strains representing the four species as well as from related volvocalean species were analyzed to elucidate the phylogenetic status of the taxonomic or morphologic species of Carteria. The sequence data showed that the 12 Carteria strains exhibit four robust monophyletic groups which are strictly consistent with the four taxonomic species. These results are discussed in relation to contrasting results found in other microalgal genera. It is concluded that phylogenetic analysis, based on DMA sequence data and comparative morphologic characterization of species and using a large number of culture strains, is essential to a natural system of microalgal species taxonomy.  相似文献   

2.
Nannochloris oculata Droop and Monallantus salina Bourrelly produce similar chloroplast pigments and show alike ultrastructural features separating them from the Chlorophyceae and Xanthophyceae, respectively, and linking them to the Eustigmatophyceae. It is proposed that N. oculata should be removed from the chlorophyceaen genus Nannochloris and transferred to a new taxon of coccoid eustigmatophytes containing the closely related M. salina: nomenclatural revisions are required for both strains.  相似文献   

3.
A new desmid genus, Actinodontum Alfinito et Coesel, is described from mountain areas of tropical Africa. The newly described genus differs from the allied genus Actinotaenium by the presence of marked teeth at the base of each semicell that alternate with those on the other semicell. Morphology of the type species, Actinodontum lomaense (Alfinito et Mazzoni) Alfinito et Coesel, is dealt with in much detail. Cosmarium basituberculoides Bourrelly et Couté and Cosmarium elgonense Kusel-Fetzmann are transferred to the new genus. The geographical distribution of the genus Actinodontum is discussed.  相似文献   

4.
Peridiniopsis polonicum (Wolosz.) Bourrelly requires vitamin B12, and Peridinium limbatum (Stokes) Lemm. requires thiamin for growth. Unlike marine Peridinium species, Peridinium willei Huit.-Kaas, P. volzii Lemm., and P. inconspicuum Lemm. do not display auxotrophy. Peridinium volzii is strongly inhibited by concentrations of biotin above 1 μg L?1.  相似文献   

5.
A technique is presented to stain, squash, and enumerate thecate dinoflagellate chromosomes using a cellulose incubation and propionocarmine stain. Chromosome numbers for six freshwater armored dinoflagellates (Peridinium cinctum (O.F.M.) Ehrenberg, P. inconspicuum Lemm., P. limbatum (Stokes) Lemm., P. volzii Lemm., P. willei Huit.-Kaas, and Peridiniopsis polonicum (Wolosz.) Bourrelly) range from 41 (P. inconspicuum) to 210 (P. cinctum). Evidence is presented for dinoflagellate aneuploidy in culture.  相似文献   

6.
Whole cell absorption spectra of the Eustigmatophycean algae Nannochloropsis salina Bourrelly and Nannochloropsis sp. reveal the presence of a distinct absorption peak at 490 nm. The lack of chlorophylls b and c in these species indicates that this peak must be attributed to carotenoid absorption. In vivo fluorescence excitation spectra for chlorophyll a emission show a corresponding maximum at 490 nm. This peak is more clearly resolved than carotenoid maxima in other algal classes due to the absence of accessory chlorophylls. The carotenoid composition of the two Nannochloropsis species shows that violaxanthin and vaucheriaxanthin are the main contributors to 490 nm absorption. Violaxanthin accounts for approximately 60% of the total carotenoid in both clones. We conclude that light absorption by violaxanthin, and possibly by vaucheriaxanthin, is coupled in energy transfer to chlorophyll a and that violaxanthin is the major light-harvesting pigment in the Eustigmatophyceae. This is the first report of the photosynthetic light-harvesting function of this carotenoid.  相似文献   

7.
Chloroplast morphology was investigated in five species of euglenophytes: Trachelomonas volvocinopsis Swirenko, Strombomonas verrucosa (Daday) Deflandre, Strombomonas costata Deflandre, Colacium mucronatum Bourrelly et Chafaud, and Colacium vesiculosum Ehrenberg. All five species share a common plastid morphotype: disk‐shaped plastids with a pyrenoid that protrudes asymmetrically toward the center of the cell and is capped by a single large grain of paramylon that conforms to the shape of the pyrenoid. Although plastids demonstrated some degree of diversity among the species studied, it was not consistent with current generic boundaries. The plastids of S. verrucosa show a developmental pattern similar to that of Euglena gracilis. The plastids divide during the early portion of the light phase after cell division, and pyrenoids are reduced or absent in dividing plastids. Developmental patterns of plastid replication also suggest that these five taxa share recent common ancestry with members of the genus Euglena subgenus Calliglena.  相似文献   

8.
A taxonomic revision of Encyclia (Orchidaceae) in Costa Rica is presented. The taxonomic history of the genus and its phylogenetic position are discussed. Characters of vegetative and floral morphology are described and their taxonomic significance is discussed. The genus is treated as comprising nine species in the country and a key to species is provided. Each taxon is described on the basis of Costa Rican material, illustrated in a composite plate, and its distribution within the country is assessed. Distribution maps for all the taxa are given. Overall distribution, derivation of name, synonymy, notes on species ecology and diagnostic features are presented for each taxon. The names Encyclia tonduziana and Epidendrum mooreanum are typified. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 395–448.  相似文献   

9.
The taxonomic status of the species Lasius mixtus, L.umbratus and L.rabaudi is discussed. Keys are given to the males, females and workers of the seven British species of the genus, and taxonomic notes on these species are included.  相似文献   

10.
The middle Triassic bivalve genusDaonella Mojsisovics, 1874 would be an ideal guide fossil (worldwide distribution, high evolutionary rates); however, the classification of daonellas is difficult. Most daonellas lack distinct characters and have a wide range of morphologic variation. A new taxonomic attempt was necessary to get a coherentDaonella classification. The new taxonomic concept proposed herein consists of four steps. (1) Biometric characters are defined unambiguously, based on landmarks and pseudolandmarks. (2) The taxonomic significance of biometric characters is analyzed. Several characters depend significantly on growth stage of specimens or on the lithology of fossil localities. In addition, the intercorrelations between biometric characters are studied to exclude weighting in some morphologic features. The study of the taxonomic significance of biometric characters shows, how important a careful selection of taxonomic characters is. (3) Most daonellas are not determinable by univariate or bivariate methods. The principle component analysis (PCA) is applied to detect groups of similar holomorphs in multivariate space. (4) The interpreted groups from PCA are applied to a canonical discriminant function analysis. This analysis helps in deciding whether two groups are sufficiently distinct to be separated as different species. This new taxonomic concept was applied to moussoneliform daonellas of the middle Triassic from the Southern Alps. Three different forms were used for the study herein:Daonella moussoni (Mérian, 1853) from the Varenna Limestone (Perledo-Varenna Formation, Grigna, Italy),D. aff.moussoni (Mérian)Rieber, 1969 from the lower Meride Limestone (Monte San Giorgio, Switzerland) andD. pseudomoussoni Rieber, 1969 from the Grenzbitumenzone (Monte San Giorgio, Switzerland). The new classification shows thatD. pseudomoussoni is a separate species and distinguishable fromD. moussoni andD. aff.moussoni, which belong to the same species. A coherent systematics ofDaonella becomes possible on the basis of newly defined taxonomic characters. Daonellas can now be used as relevant guide fossils for the middle Triassic. The presented example demonstrates a biostratigraphic correlation between the lower Meride Limestone at Monte San Giorgio and the Varenna Limestone at Grigna. The stratigraphic distribution ofD. moussoni can be assigned to thegredleri Zone.  相似文献   

11.
Packroff  Gabriele  Woelfl  Stefan 《Hydrobiologia》2000,433(1-3):153-156
The occurrence and some important taxonomic problems of heterotrophic protists from extremely acidic (pH 3) environments are briefly discussed. Almost all information on the occurrence of heterotrophic protists from extremely acidic environments is restricted to acid mine drainage (AMD) or streams influenced by AMD. Most of the information is provided for ciliates. Very little information is available on the occurrence of flagellates, rhizopods and heliozoa in this environment. Within the ciliates Urotricha, Vorticella and Oxytricha dominate in acidic mining lakes. Actinophrys sp. is the most important heliozoan in these environments. There are many taxonomic problems which are not solved so far. Live observations and taxonomic methods adapted to the extreme chemical matrix are necessary for correct identification.  相似文献   

12.
Thraustochytrium is the type genus of the family Thraustochytriaceae in the class Labyrinthulomycetes. This genus is characterized by zoospore formation, namely, shape of the cell wall of sporangia and presence or absence of a proliferous body. However, there are several issues associated with the taxonomy of this genus, and these include polyphyletic taxa and overlapping of taxonomic features among species. In particular, the first and second species, T. proliferum and T. globosum, were described based on observations of the morphological features of natural samples in the absence of culture conditions. Before addressing the taxonomic issues associated with this genus, it is important to consider the taxonomic features of each species, i.e., the life history under culture conditions and the phylogenetic position. The objective of the present study was to isolate T. globosum, the second described species in the genus Thraustochytrium, from the type locality. We successfully isolated strain NBRC 112723, which exhibited characteristic features of T. globosum. Under culture conditions, strain NBRC 112723 exhibited taxonomic features observed in other thraustochytrid species. Our molecular phylogeny indicated that this strain isolated from the type locality was located in an unidentified thraustochytrid group; moreover, some strains located in this group exhibited characteristic features of strain NBRC 112723. We clearly distinguished T. globosum based on the taxonomic criteria used to classify the T. proliferum type species. Therefore, we propose the establishment of a new genus, Monorhizochytrium, for the species T. globosum in the family Thraustochytriaceae.  相似文献   

13.
Aim The ‘taxonomic impediment’ has led to a growing trend in ecology and conservation biology to use operational surrogates for species within the context of a particular research project. Because such ‘parataxonomic’ classifications are typically spatially limited in scope, we examined the influence of increasing spatial scale on the congruence of two such approaches with a more traditional taxonomic classification. Location Sturt National Park, north‐western New South Wales, Australia. Methods Specimens of two ant genera, Camponotus and Rhytidoponera, were classified by three independent methods. The ‘parataxonomic’ classification assigned specimens to morphospecies without specialist taxonomic expertise; the ‘taxonomic’ classification assigned specimens to either described species or, where this was not possible, to operational taxonomic units (OTUs) using specialist taxonomic expertise; the ‘phenetic’ classification assigned specimens to putative species using a K‐means partitioning algorithm on basic morphometric data. Specimens of each genus were pooled into ‘assemblages’, which were defined at multiple spatial scales using a nested sampling design. Congruence in the interspecimen relationships of the different classifications was tested for each assemblage using pair‐wise Mantel correlations. Results Classification congruence tended to decrease with increasing spatial scale. There were, however, clear differences between the genera. Parataxonomic–taxonomic congruence was consistently greater for Camponotus, while phenetic–taxonomic congruence showed the opposite pattern. Conclusions Observed patterns in classification congruence are attributed to two principal causes: (i) within‐species morphological variation, including ecotypic variation in Rhytidoponera and caste polymorphism in Camponotus; and (ii) a limit to the morphological similarity of potentially competing species at small spatial scales. Regardless of cause, the decline in agreement as the spatial scale of observation is increased has important implications for the measurement of biodiversity, particularly when comparing samples over regional, continental, and global scales.  相似文献   

14.
The ultrastructure of the freshwater, heterotrophic dinoflagellate Peridiniopsis berolinense (Lemm.) Bourrelly resembles other dinoflagellates in the structure of its nucleus, theca, flagella, and mitochondria. Other features less frequently reported in related organisms include fine sub-sulcal fibers, collared pits in the flagellar base region, and unusual structures herein termed fibrillar lamellae. Numerous vesicles are present, some of whose contents are distinctly crystalline, while others contain what appears to be membranous material arranged in either whorls or parallel stacks; still other vesicles contain electron-dense, granular spheres. Of particular interest is the transitional helix present in the longitudinal flagellum, this being the first report of such a structure among the dinoflagellates. Plastids of any kind are lacking, and a peduncle is present and is used during phagotrophy.  相似文献   

15.
16.
To resolve the current taxonomic status of Japanese endemic Fritillaria L., their taxonomic history is retraced. All taxonomic papers are evaluated, together with more recent genetic observations. To determine the wider acceptance of various taxonomic revisions, a range of Floras are also examined. It is evident that articles published in Japanese have not been fully considered by the wider botanical community. Moreover, rivalries between the Tokyo and Kyoto schools of botany and an over-reliance on herbarium material by many authors have undermined the current classification of the Fritillaria ‘japonica group’.  相似文献   

17.
Charles R. Lane 《EcoHealth》2007,4(2):219-230
Diatoms are useful indicators of aquatic conditions, and metrics based on published autecological indicator values have been developed utilizing their sensitivities to various ambient physical and chemical conditions. The autecological values often differ within genera, and indeed within species taxonomic levels, requiring identification to subspecies taxonomic level for accurate application. This study was conducted to determine if autecological metrics, and ultimately indices of biotic integrity, could be developed using mean autecological values at the genus, species, and subspecies taxonomic levels, and to investigate the potential benefits of increased taxonomic resolution. Sixty-nine isolated herbaceous wetlands in various land use modalities in peninsular Florida were sampled a single time for epiphytic diatoms, and soil/water physicochemical parameters. Thirty genera, 148 species, and 26 subspecies were identified. The proportional matrices at each taxonomic level were highly similar (Mantel’s r > 0.75, P < 0.0001). Autecological metrics and two sensitive or tolerant measures were developed at each taxonomic level. Wetland condition, as determined by summed metric values, was strongly correlated across taxonomic level (r 2 > 0.83, P < 0.0001), and no significant difference was found when sites were placed into bins of excellent, good, fair, or poor, based on quartile scoring, for each taxonomic level. Specific conductance, soil pH, soil and water total phosphorous, and water color were significantly related to site non-metric multidimensional scaling (NMDS) ordination scores at each taxonomic level. This study concludes that indices of biotic integrity, when developed using autecological indices, provide similar qualitative conditional information across taxonomic levels for isolated herbaceous wetlands. Electronic supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

18.
19.
A brief review of past taxonomic assessments of the allopatric gray-cheeked mangabey (Cercocebus albigena) and the black mangabey (Cercocebus aterrimus) is presented. On the basis of pelage, cranial, and biomolecular morphology, aterrimus and albigena have been lumped together in the same species-group, superspecies, subgenus, or species by various systematists over the years. A comparison of the available socioecological data on the two forms supports their close taxonomic association, as they are found to be very similar in socioecological traits. After a brief review of current species concepts, the author, on the basis of the socioecological commonalities, tentatively supports Groves' [1978] conspecific designation of albigena and aterrimus and suggests further tests for this proposal and for the species concept, from the points of view of both taxonomic and evolutionary theory.  相似文献   

20.
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