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1.
Gymnopus piceipes is proposed as a new species within the sectionVestipedes. It is characterized by a brown pileus, pale brown close lamellae, a solid black stipe that is not insititious, and conspicuous pleurocystidia.  相似文献   

2.
We describe here Sinaster petalon gen. et sp. nov., a new embryonic form from the c. 535 million‐year‐old Kuanchuanpu Formation of South China (Ningqiang, Shaanxi Province). The excellent three‐dimensional, phosphatic preservation of these microfossils allowed us to use x‐ray microtomographic techniques to make accurate reconstructions of their internal structures and to compare their anatomy point‐by‐point with that of extant cnidarians and other animal groups. Sinaster petalon has anatomical features typical of extant Medusozoa (Cnidaria), such as coronal muscles, perradial and adradial frenula, interradial septa, accessory septa, gonad‐lamellae, tentacle buds and perradial pockets. Although Sinaster cannot be straightforwardly assigned to any crowngroup within Medusozoa, the presence of marginal lappets and endodermal lamellae suggests that it is closer to Cubozoa and Scyphozoa than to any other group of modern cnidarians. The tentative placement of Sinaster within the stem‐group Cubozoa is justified by the presence of a velarium supported by a frenulum. The cubozoan affinities of Sinaster are also supported by cladistic analysis.  相似文献   

3.
Radial sculptural elements (e.g. ribs, lirae), formed by imbrication of two succeeding shell lamellae are found in members of both the Nautiloidea (Cymatoceras) and Ammonoidea (Phylloceratinae and Aspidoceratinae). Their formation involves periodic cessation of shell growth due to weak to moderate withdrawal of the shell secreting mantle. The radial lirae (0.5–1.5 mm in width) of Phylloceratinae and Aspidoceratinae (Aspidoceras and Pseudowaagenia) are created by the succession of sigmoid lamellae of the organic periostracum or of the outer prismatic layer, respectively. Each lira has a characteristic adorally‐projecting, scythe‐like appendage, arising from its crest. The prismatic lirae of Aspidoceras and Pseudowaagenia are analogous to the larger scaled pseudoribs of Cymatoceras. Garland‐like lamellae of the outer prismatic layer form the radial lirae of Mirosphinctes and Epaspidoceras (Aspidoceratinae), but these lack a conspicuous, projecting scythe‐like appendage. Additional prismatic cement is formed within adoral, oval hollow spaces of scythe‐appendage‐bearing lirae, either through diagenetic crystal growth, remote biomineralization or as a component of the dorsal shell. In Aspidoceratinae these prismatic infillings are replaced by a continuous herringbone layer, accompanied by a reduction of the lirae.  相似文献   

4.
An examination of a series of collections from the coast of Natal, South Africa, has revealed the presence of two species of Martensia C. Hering nom. cons: M. elegans C. Hering 1841, the type species, and an undescribed species, M. natalensis sp. nov. The two are similar in gross morphology, with both having the network arranged in a single band, and with reproductive thalli of M. elegans usually larger and more robust than those of M. natalensis. Molecular studies based on rbcL sequence analyses place the two in separate, strongly supported clades. The first assemblage occurs primarily in the Indo‐West Pacific Ocean, and the second is widely distributed in tropical and warm‐temperate waters. Criteria that have been used in the past for separating the two, namely, the number and shape of the blades, the presence of a single‐ versus a multiple‐banded network, and blade margins entire or toothed, were determined to be unreliable. Although the examination of additional species is required, the morphology and position of procarps and cystocarps, whether at or near the corners of the longitudinal lamellae and the cross‐connecting strands or along the lobed, membranous edges of the longitudinal lamellae or on the thallus margins, may prove to be diagnostic at the subgenus level. We recognize subg. Martensia, including the type of Martensia: M. elegans and subg. Mesotrema (J. Agardh) De Toni based on Martensia pavonia (J. Agardh) J. Agardh.  相似文献   

5.
6.
On the basis of LM, we isolated strains of two species of fusiform green flagellates that could be assigned to former Chlorogonium (Cg.) Ehrenb. One species, “Cg.”heimii Bourr., lacked a pyrenoid in its vegetative cells and required organic compounds for growth. The other was similar to Cg. elongatum (P. A. Dang.) Francé and “Cg.”acus Nayal, but with slightly smaller vegetative cells. Their molecular phylogeny was also studied based on combined 18S rRNA, RUBISCO LSU (rbcL), and P700 chl a‐apoprotein A2 (psaB) gene sequences. Both species were separated from Chlorogonium emend., Gungnir Nakada and Rusalka Nakada, which were formerly assigned to Chlorogonium. They were accordingly assigned to new genera, Tabris Nakada gen. nov. and Hamakko (Hk.) Nakada gen. nov. as T. heimii (Bourr.) Nakada comb. nov. and Hk. caudatus Nakada sp. nov., respectively. Tabris is differentiated from other genera of fusiform green flagellates by its vegetative cells, which only have two apical contractile vacuoles and lack a pyrenoid in the chloroplast. Hamakko, on the other hand, is distinguishable by the fact that its pyrenoids in vegetative cells are penetrated by flattened thylakoid lamellae.  相似文献   

7.
Robby Stoks 《Oecologia》1998,117(3):443-448
Damselfly larvae can autotomize their caudal lamellae to escape predation. Costs of caudal lamellae autotomy were investigated by directly manipulating lamellae condition of Lestes sponsa in laboratory experiments. Larvae without lamellae had higher predation mortality in the presence of Notonecta. Both lamellae loss and larval density increased the probability of being cannibalized. The results suggest that the increased vulnerability after lamellae loss resulted from a reduced escape performance. Larvae were less mobile after lamellae loss or in the presence of a predator, but the decrease was no longer significant when both factors were combined. This indicates that larvae compensate for the increased predation risk with a fixed response. Both lamellae loss and predator presence reduced hunting success, but the decrease after lamellae loss was only significant in the absence of a predator. The fitness consequences of these effects for both the larval and adult stages are discussed. In general, the data strongly suggest that lamellae autotomy plays a role in population regulation of damselflies. Received: 1 April 1998 / Accepted: 28 August 1998  相似文献   

8.
Impatiens L. is one of the largest angiosperm genera, containing over 1000 species, and is notorious for its taxonomic difficulty. Here, we present, to our knowledge, the most comprehensive phylogenetic analysis of the genus to date based on a total evidence approach. Forty‐six morphological characters, mainly obtained from our own investigations, are combined with sequence data from three genetic regions, including nuclear ribosomal ITS and plastid atpB‐rbcL and trnL‐F. We include 150 Impatiens species representing all clades recovered by previous phylogenetic analyses as well as three outgroups. Maximum‐parsimony and Bayesian inference methods were used to infer phylogenetic relationships. Our analyses concur with previous studies, but in most cases provide stronger support. Impatiens splits into two major clades. For the first time, we report that species with three‐colpate pollen and four carpels form a monophyletic group (clade I). Within clade II, seven well‐supported subclades are recognized. Within this phylogenetic framework, character evolution is reconstructed, and diagnostic morphological characters for different clades and subclades are identified and discussed. Based on both morphological and molecular evidence, a new classification outline is presented, in which Impatiens is divided into two subgenera, subgen. Clavicarpa and subgen. Impatiens; the latter is further subdivided into seven sections.  相似文献   

9.
10.
Sprouting ability is highly variable among different tree species. In many cases, there are trade‐offs in carbon allocations between growth and storage in seedlings. However, this trade‐off is likely to change with growth stages from seedling to mature plant because carbon investments in reproductive activities and/or risk of disturbance also change by species and growth stage. To examine how sprouting ability and carbohydrate storage change with growth stage, we compared two tropical secondary‐forest trees, Macaranga bancana and M. gigantea, which have different ecological traits. Maximum tree size and growth rate are higher in M. gigantea. We monitored sprout growth and stored resources, including total non‐structural carbohydrate (TNC) and nitrogen in the root, among different tree sizes for 12 months following stem‐cutting treatment. Sprouting ability (total sprout mass) and TNC concentrations were significantly higher in small individuals than in larger specimens in both species. TNC concentration decreased in all size classes after stem cutting. Macaranga bancana had greater sprout survivorship than M. gigantea, which had higher sprouting ability in larger tree‐size classes. Thus, sprouting ability likely depends on root TNC concentration and tree‐size class in both Macaranga species. Higher TNC concentration and sprout survival rates in M. bancana may be related to greater carbon allocation in survival than in growth. This hypothesis is consistent with the ecological traits of M. bancana, such as its growth rate, which was lower than that of M. gigantea.  相似文献   

11.
Two new species of Martensia (Delesseriaceae, Rhodophyta) are described from Jeju Island, Korea. Martensia jejuensis is characterized by the thallus of long linear axes and a proximal membranous part (initial blade), the linear axes that are derived from the longitudinal lamellae of the latticework, the flabellate bladelets arising from the linear axes terminally and laterally, the leading margins of the latticework giving rise to spine‐like or spatulate projections at intervals, and tetrasporangia borne on the whole thallus except for the spatulate projections. Martensia bibarii is characterized by the fimbriate aspect, the ribbon‐like blade with lobes, the flabellate bladelets derived from the lobes of the blade, the bladelets bearing the fringe or the latticework distally, the fringe consisting of many fine and strap‐shaped lamellae, and tetrasporangia borne only on the blade.  相似文献   

12.
D‐Glucaric acid can be produced as a value‐added chemical from biomass through a de novo pathway in Escherichia coli. However, previous studies have identified pH‐mediated toxicity at product concentrations of 5 g/L and have also found the eukaryotic myo‐inositol oxygenase (MIOX) enzyme to be rate‐limiting. We ported this pathway to Saccaromyces cerevisiae, which is naturally acid‐tolerant and evaluate a codon‐optimized MIOX homologue. We constructed two engineered yeast strains that were distinguished solely by their MIOX gene – either the previous version from Mus musculus or a homologue from Arabidopsis thaliana codon‐optimized for expression in S. cerevisiae – in order to identify the rate‐limiting steps for D‐glucaric acid production both from a fermentative and non‐fermentative carbon source. myo‐Inositol availability was found to be rate‐limiting from glucose in both strains and demonstrated to be dependent on growth rate, whereas the previously used M. musculus MIOX activity was found to be rate‐limiting from glycerol. Maximum titers were 0.56 g/L from glucose in batch mode, 0.98 g/L from glucose in fed‐batch mode, and 1.6 g/L from glucose supplemented with myo‐inositol. Future work focusing on the MIOX enzyme, the interplay between growth and production modes, and promoting aerobic respiration should further improve this pathway.  相似文献   

13.
Three separate collections of the type material of Kjellman's Lithophyllum arcticum are re‐examined and a lectotype is selected. It is confirmed that the thallus is unattached, at least 4.5 cm in diameter, composed of up to eight superimposed more or less discoidal lamellae, provided with concentric striations on the surface. Individual lamellae are usually 100 to 200 μm thick (reaching 1 mm), developing dorsally from the main thallus and expanding centrifugally. The internal organization is dorsiventral with a polystromatic hypothallium, giving rise to an ascending perithallium with small subepithallial initials and rectangular (in TS) epithallial cells. It is found that patches of coaxial‐like growth occur sporadically in the hypothallium and the perithallium, and that ventral lamellae may grow back‐to‐back. Somatic cells exhibit both large and narrow cell fusions. Pore plates of the raised multiporate conceptacles are slightly sunken to flattened and perforated by 16 to 31 pores. Pore canals are conical (narrowing towards the top) and are bordered by filaments composed of both undifferentiated and slender‐elongate cells. Old conceptacles are overgrown by vegetative filaments and empty chambers are embedded in the perithallium. Collectively these features indicate that L. arcticum belongs to the subfamily Melobesioideae. The development of an unattached‐superimposed thallus, patches of coaxial growth, short subepithallial initials and specialized pore cells suggest a position either in Mesophyllum, or in an amended Leptophytum to include even species with coaxial patches and unattached‐superimposed habit (characters presently segregating Leptophytum from Synarthrophytorn). The holotype of Lithophyllum zonatum from East‐Finnmark, previously considered to be related to L. arcticum, is re‐examined and shown to belong to a different species. A previous Arctic record of Mesophyllum lichenoides from Spitsbergen is abolished, and thus the disjunct distribution of I. arcticum in relation to Mesophyllum suggests a position in the Synarthrophyton‐Leptophytum complex which shows a bipolar to temperate distribution.  相似文献   

14.
Rising temperatures are predicted to melt all perennial ice cover in the Arctic by the end of this century, thus opening up suitable habitat for temperate and subarctic species. Canopy‐forming seaweeds provide an ideal system to predict the potential impact of climate‐change on rocky‐shore ecosystems, given their direct dependence on temperature and their key role in the ecological system. Our primary objective was to predict the climate‐change induced range‐shift of Fucus distichus, the dominant canopy‐forming macroalga in the Arctic and subarctic rocky intertidal. More specifically, we asked: which Arctic/subarctic and cold‐temperate shores of the northern hemisphere will display the greatest distributional change of Fdistichus and how will this affect niche overlap with seaweeds from temperate regions? We used the program MAXENT to develop correlative ecological niche models with dominant range‐limiting factors and 169 occurrence records. Using three climate‐change scenarios, we projected habitat suitability of Fdistichus – and its niche overlap with three dominant temperate macroalgae – until year 2200. Maximum sea surface temperature was identified as the most important factor in limiting the fundamental niche of Fdistichus. Rising temperatures were predicted to have low impact on the species' southern distribution limits, but to shift its northern distribution limits poleward into the high Arctic. In cold‐temperate to subarctic regions, new areas of niche overlap were predicted between Fdistichus and intertidal macroalgae immigrating from the south. While climate‐change threatens intertidal seaweeds in warm‐temperate regions, seaweed meadows will likely flourish in the Arctic intertidal. Although this enriches biodiversity and opens up new seaweed‐harvesting grounds, it will also trigger unpredictable changes in the structure and functioning of the Arctic intertidal ecosystem.  相似文献   

15.
Wahlenbergia cordiformis, a new species of the Lightfootia‐type is described and illustrated. It is currently only known from the farm Knolfontein, in the Swartruggens region, north east of Ceres in the Western Cape, South Africa. The closest relative of W. cordiformis is unclear, but it may be closely related to either W. tenella, W. nodosa, W. tenerrima, W. oligantha or W. neorigida. Wahlenbergia cordiformis is distinguished from them by its cordate, leaf‐like calyx lobes.  相似文献   

16.
Anacystis nidulans was grown at two different levels of white light, 7 and50 W.m?2. The cells were disrupted through French press treatment, and phycocyanin-free photosynthetic lamellae were obtained from the homogenate by fractionated centrifugation. Comparative absorption studies of the lamellae revealed that high intensity gave an increased carotenoid content relative to chlorophyll a. The spectral characteristics of the cell-free supernatants were also analysed. The high light intensity gave increased contents of both pteridines (410 nm) and allophycocyanin (655 nm) compared with the contents in algae grown at the low light level.  相似文献   

17.
Cousinia brevicaulis is described and illustrated as a new species from eastern Iran. This species belongs to the C. sect. Lasiandra Bunge as defined by hairy anther tube, yellow, pale yellow or rarely milky flowers, monocarpic growth form and corymbose branching of stem. It is easily distinguished from other species of the section by its very short‐stemmed habit. The new species is distributed in the same region as other species of C. sect. Lasiandra.  相似文献   

18.
This article describes a new diatom genus Moreneis from the Yellow Sea sand flats on the west coast of Korea. The new genus is characterized by a unique combination of morphological characteristics, including the shape of the plastids, which have not been previously observed in diatoms. The valve morphology resembles other genera belonging to Lyrellaceae, within which we place this genus. In terms of areolae structure, Moreneis resembles Petroneis and Placoneis; however, it differs from both genera with respect to the raphe system and plastid shape. Cells of Moreneis spp. have a single large plastid appressed to the girdle of the secondary side of the valve, with two lobes extended toward the primary side of the valve. Furthermore, the unique feature of Moreneis frustules is the raphe, which has both external central and apical endings bent in opposite directions. We differentiated four taxa, which we describe as new for science. However, based on our findings, several established species from Navicula should also be formally transferred to Moreneis, including N. alpha Cleve, N. besarensis Giffen, N. epsilon Cleve, N. menaiana Hendey, N. polae Heiden, and N. quadri‐undulata F. Meister. Analysis of published data revealed that species belonging to Moreneis are numerous in tropical marine littoral waters, and in moderate climate zones, especially in the western Pacific, with only a few species occurring in the Mediterranean and Atlantic.  相似文献   

19.
Krapf  Götz  Jacobi  Günter 《Planta》1975,123(2):145-154
Summary Photooxidation of hydroxylamine to nitrite by spinach (Spinacia oleracea L. and sugarbeet (Beta vulgaris L.) chloroplast lamellae in the presence of autoxidable electron acceptors is inhibited by either solubilized or membrane-bound superoxide dismutase (SOD). This inhibition is reversed by KCN. The rates of hydroxylamine photooxidation by chloroplast lamellae, a reaction which is apparently driven by the superoxide free-radical ion, was used for quantitating the amount of SOD bound to chloroplast lamellae, as compared to a soluble enzyme of defined concentration. After digitonin fragmentation of chloroplast lamellae, ca. 80% of the SOD activity is associated with subchloroplast particles sedimenting after 2 h centrifugation at 200 000 x g. Less than 10% of the SOD activity is associated with particles sedimenting after centrifugation for 30 min at 20 000 x g. 5–10% of the cyanide-sensitive SOD is recovered in the soluble fraction of the subchloroplast-free supernatant after centrifugation at 200 000 x g for 2 h.Abbreviation SOD superoxide dismutase  相似文献   

20.
Gong, Y.‐M., Shi, G.R., Zhang, L.‐J. & Weldon, E.A. 2009: Zoophycos composite ichnofabrics and tiers from the Permian neritic facies in South China and south‐eastern Australia. Lethaia, Vol. 43, pp. 182–196. Zoophycos composite ichnofabrics (ZCI) comprising two or more suites of the same form of Zoophycos are widespread and densely distributed in Early and Middle Permian (Cisuralian–Guadalupian) neritic limestones (Qixia and Maokou Formations) of palaeotropical origin in the Laibin area, Guangxi, South China. Similar ZCI also occur in neritic greywackes of glaciomarine origin from the Middle Permian (Guadalupian) Westley Park Sandstone Member (Broughton Formation) in the southern Sydney Basin, south‐eastern Australia. Zoophycos from both regions consists of planar spreite with major and minor lamellae and a cylindrical tunnel interpreted as a marginal tube and/or axial shaft. The cylindrical tunnel is herein considered to be an essential component of Zoophycos, and thus can be used to define and characterize the morphological variability of Zoophycos. It is suggested that the variation of spreite and major and minor lamellae originated from the different morphologies and migration manners of the cylindrical tunnel. The shallowest, shallow, middle and deepest Zoophycos tiers have been distinguished in ZCI on the basis of cross‐cutting relationships, the soft‐sediment deformation and the contrast in colour between Zoophycos and its host rock. The multiple tiers may represent the substrate consistency spectrum from a softground through a stiffground to a firmground. The different Zoophycos tiers may have been constructed by tracemakers of either different or the same taxonomic affinities in response to the gradual accretion and lithification of sediment layers on the seafloor. The tracemakers appeared to be very sensitive to neither climate nor lithology. The width of the planar spreiten of Zoophycos decreases slightly with the depth of tiering in ZCI. □Composite ichnofabric, Permian, South China, south‐eastern Australia, tier, Zoophycos.  相似文献   

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