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1.
Phylogeny of the genus Pythium is analyzed based on sequences of the large subunit ribosomal DNA D1/D2 region and cytochrome oxidase II gene region of Pythium isolates and comprehensive species of related taxa belonging to the Oomycetes. The phylogenetic trees show that the genus Pythium is a highly divergent group and divided into five well- or moderately supported monophyletic clades. Each clade is characterized by sporangial morphology such as globose, ovoid, elongated, or filamentous shapes. Based on phylogeny and morphology, the genus Pythium (s. str.) is emended, and four new genera, Ovatisporangium, Globisporangium, Elongisporangium, and Pilasporangium, are described and segregated from Pythium s. lato.  相似文献   

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Liu ZJ  Chen LJ  Chen SC  Cai J  Tsai WC  Hsiao YY  Rao WH  Ma XY  Zhang GQ 《PloS one》2011,6(10):e24864

Background

Holcoglossum is a small orchid genus of 12 species ranging from SW China to Thailand and NE India. Although molecular and morphological analyses have been performed to establish the phylogenetic relationships within this genus, the interspecific relations and its relations with allied genera, such as Rhynchostylis, Aerides and Vanda, remain unclear.

Methodology/Principal Findings

In addition to morphological analysis, maximum parsimony, maximum likelihood, and Bayesian inference analyses were performed based on fragments of the nuclear ITS and chloroplast trnL-F and matK genes of 31 taxa (15 Holcoglossum, 14 Aeridinae, 2 outgroups) representing all major clades of the Holcoglossum alliance. The results suggest that Holcoglossum is triphyletic, comprising three clades: the Holcoglossum clade, its sister clade, and a distant clade more closely related to Rhynchostylis, Aerides, and Vanda than to the Holcoglossum clade. The Holcoglossum clade is further divided into three subclades; the genetic distances between these three subclades also support this delimitation. The molecular conclusion is consistent with their distinct morphological characters.

Conclusions

We propose that the latter two clades comprise two new genera, Paraholcoglossum and Tsiorchis, and Holcoglossum clade divides into three sections. In addition, a new section, Holcoglossum sect. Nujiangensia, and a new species, Holcoglossum linearifolium, are proposed. Some new combinations are made, and a new scheme is provided for the classification of all species of Holcoglossum, Paraholcoglossum, and Tsiorchis.  相似文献   

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《Phytochemistry》1985,24(9):2120-2122
From the orchid Cirrhopetalum elatum was isolated a new triterpene of the cycloartane series, which was shown to be 24-methylenecycloartanyl p-hydroxycinnamate from spectral and chemical evidence.  相似文献   

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We have previously shown that the systemic injection of sodium tungstate, a protein-tyrosine phosphatase (PTPase) inhibitor, to pupae immediately after pupation efficiently produces characteristic color-pattern modifications on the wings of many species of butterflies including Vanessa indica and Cynthia cardui. In these species, the black spots reduced in size in response to the treatment. Similar modifications are occasionally seen in the field-caught aberrant individuals. Exceptionally, however, a C. cardui individual with enlarged black spots ("reversed" modification pattern) has been reported. Here we show that these modified patterns of V. indica and C. cardui are quite similar to the normal color-patterns of other Vanessa species. V. indica with tungstate-induced modifications resembled V. tameamea, V. samani, and Bassaris itea, whereas V. dilecta, V. atalanta, and V. dejeanii are similar to the "reversed" individual. Most features seen in the experimentally-modified V. indica were observed throughout the fore- and hindwings of V. samani. In contrast, the experimentally-induced color-patterns of C. cardui did not parallel variation of Cynthia butterflies. Since it has been proposed that a hypothetical transduction pathway with a PTPase for the scale-cell differentiation globally coordinates the wing-wide color-patterns, our findings suggest that spontaneous mutations in genes in this hypothetical pathway might have played a major role in creating new color-patterns and species in the Vanessa genus but not in the Cynthia genus. This evolutionary mechanism may probably be shared more widely in Lepidoptera, although this would not be a sole determinant for the color-pattern development and evolution.  相似文献   

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Dactylogyrus is the largest helminth genus, with more than 900 nominal species, and is consequently in a state of considerable confusion. In an attempt to consolidate our knowledge of this large taxon, this work surveys the nominal species and catalogues them and their hosts (to the generic level) in the form of a species list which is cross-referenced to host-parasite list. A reference list to the authorities for the taxa is included.  相似文献   

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The taxonomy of the genera Moraxella and Neisseria   总被引:7,自引:0,他引:7  
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The genera Leucothrix and Thiothrix   总被引:11,自引:0,他引:11  
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A phylogenetic analysis based on 16S rRNA was performed on the genera Planococcus, Marinococcus, Sporosarcina and endospore-forming rods. In agreement with earlier 16S rRNA cataloguing data, Planococcus citreus and Sporosarcina ureae clustered with Bacillus pasteurii and other bacilli containing lysine in their cell walls. Sporosarcina halophila was shown to be genetically distinct from S. ureae and formed a loose association with the main Bacillus subtilis grouping. Marinococcus halophilus (formerly Planococcus halophilus) exhibited low levels of relatedness to all reference species examined and formed a distinct line of descent.  相似文献   

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Previous molecular phylogenetic studies of the genus Chondrostoma (Cyprinidae: Leuciscinae) were unable to resolve the relationship among its major species groups. In this paper we present a phylogeny for this genus, based on five mitochondrial genes and the nuclear gene beta-actin, comprising a total of 4068 bp. Bayesian inference using all gene fragments yielded a fully resolved phylogeny, compatible with topologies obtained from individual fragments using maximum parsimony and minimum evolution. Mapping of morphological characters critical to the rasping feeding mode of most Chondrostoma species indicates that they evolved several times, and questions the use of these characters in the traditional definition of the genus. Our findings led us to the definition of the following new genera: Achondrostoma, Iberochondrostoma, Pseudochondrostoma, Protochondrostoma and Parachondrostoma. Our data contradict the hypothesis of a rapid radiation during Lago Mare phase, suggested by previous studies.  相似文献   

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Ichthyological Research - A taxonomic review of the waspfish genus Neocentropogon Matsubara 1943 (Tetrarogidae), diagnosed by the following combination of characters: body sparsely covered with...  相似文献   

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Surface sterilization is generally used for isolating lichen-inhabiting fungi as well as endophytic fungi, and ethanol and sodium hypochlorite are commonly used as the sterilizer. However, there are few studies on whether the type of chemicals used for surface sterilization affects the isolation results of lichen-inhabiting fungi. In this study, the genus composition of the lichen-inhabiting fungi of two lichen species (Flavoparmelia caperata and Peltigera dilacerata) were investigated 1) to reveal how the isolation result changes before and after surface sterilization and 2) to examine the effect of the sterilizer (ethanol, sodium hypochlorite, or hydrogen peroxide) on the composition of the isolated fungi. We isolated 652 non-lichenized fungal isolates from the two-lichen species and identified 84 genera. It was found that 1) every sterilizer effectively removed the fungi on the lichen surface and that 2) the composition of isolated fungi varied depending on the type of surface sterilizer. It was also shown that, such as the genus Sarea, there were some lichen-inhabiting fungi which could not be isolated at all by surface sterilization with ethanol or sodium hypochlorite, which are commonly used. In addition, the genus Virgaria was detected as lichen-inhabiting fungi for the first time. Our results suggest that single surface sterilization alone may underestimate the genus composition of lichen-inhabiting fungi.  相似文献   

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The results of the identification of 21 ergoline alkaloids of 14 species of Argyreia; viz.: A. barnesii, A. capitata, A. cuneata, A. luzoninsis, A. mollis, A. maingayi, A. nervosa, A. obtusifolia, A. philippinensis, A. reticulata. A. ridleyi, A. rubicunda, A. splendens and A. sp. and 2 closely related genera; Stictocardia tiliafolia and Rivea corymbosa, by using 2-D TLC procedures are given. A brief discussion of the implications of the ergoline alkaloids and the chemotaxonomy of the Convolvulaceae is also presented.  相似文献   

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Longevity of a taxonomic group is an important issue in understanding the dynamics of evolution. In this respect a key observation is that genera, families or orders can each be assigned a characteristic average lifetime (Van Valen in Evol Theory 1:1–30, 1973). Using the fossil marine animal genera database (Sepkoski in Bull Am Paleontol 363, pp 563, 2002) we here examine the relationship between longevity of a higher taxonomic group (orders) and the longevity of its lower taxonomic groups (genera). We find insignificant correlation between the size of an order and its longevity, whereas we observe large correlation between the lifetime of an order and the lifetime of its constituent genera. These observations suggest that longevity of taxonomic groups is heritable intrinsically or on the grounds of environmental preferences.  相似文献   

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