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1.
A new species, Sphacelotheca polygoni-persicariae, parasitizing the ovaries of Polygonum persicaria L. is described. This smut, collected several times in Madeira, Portugal, differs from other species of that genus, by its host plant and the reticulated teliospore ornamentation. On the basis of the morphological and ultrastructural characters of S. polygoni-persicariae, in connection with some recently published data on siderophore formation and 5S ribosomal RNA sequences it can be assumed that 1) members of the genus Sphacelotheca are separated from typical Ustilago species of Poaceae, 2) Sphacelotheca is restricted to species parasitizing Polygonaceae, and 3) species of Sphacelotheca and Microhotryum as well as those Ustilago species which parasitize in the flowers of Polygonaceae are closely related.  相似文献   

2.
New chromosome observations are reported for 30 species and varieties from 4 genera of Ambrosieae: Ambrosia (including Franseria), Diceria, Hymenoclea and Iva. Neither polyploidy nor aneuploidy is known in the genera Dicorea, Hymenoclea or Xanthium. Aneuplcid reduction appears to have played a role in the genome evolution of several species of Iva and Ambrosia. Polyploid species occur in both Iva and Ambrosia and polyploid series exist for at least 5 species or species aggregates of the latter. All available evidence indicates that the primitive chromosome number for the tribe is x = 18, differentiation and speciation having occurred at this level, which is here termed diploid. The group, however, must ultimately have been of polyploid origin from forms with x = 9.  相似文献   

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Chassalia magnificens, a new species from the Albertine Rift in eastern Democratic Republic of Congo, is described and illustrated. The species is recognised inter alia by its large stipules and montane habitat. Chassalia chrysoclada is a new combination for a widespread, but hitherto overlooked, central African species originally described in the genus Psychotria. Chassalia chrysoclada is related to C. pteropetala (K. Schum.) Cheek but lacks the bicostate twigs and dorsally winged corolla lobes of that species.  相似文献   

5.
Sphagnum magellanicum has been viewed as being a predominantly circumpolar species in the northern hemisphere, but it occurs in the southern hemisphere and was originally described from the southern parts of Chile. It is an ecologically important species in mire ecosystems and has been extensively used as a model to study processes of growth, carbon sequestration and peat decomposition. Molecular and experimental studies have, however, revealed genetic structure within S. magellanicum, and morphological differences associated with these genetic groups. Here we describe Sphagnum divinum in Sphagnum subgenus Sphagnum (Sphagnaceae, Bryophyta) as a new species, based on molecular and morphological evidence. Sphagnum medium is reinstated as a distinct species and is epitypified. Consequently, a new species concept of S. magellanicum is presented including an epitypification. Important morphological characters to separate these three species in the field and under the microscope are presented. Ecology and distribution differ among the species; S. divinium has a wide habitat range including mire margin, forested peatlands and moist heaths, and a circumpolar distribution around the northern hemisphere. Sphagnum medium seems to be more restricted to ombrotrophic mire expanse habitats and shows an amphi-Atlantic distribution in the northern hemisphere. Sphagnum magellanicum has a very broad ecological niche in peatlands and is found in most mire habitats in Tierra del Fuego on the southern tip of South America.  相似文献   

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A reinvestigation of the 4 American species of Lepidocarpon described from petrifactions and of Illiniocarpon cadyi, also described from petrifactions, shows that they are all conspecific. When they, in turn, are compared with specimens of the British petrifaction L. lomaxi, no significant differences can be demonstrated. The criteria cited as diagnostic for the American petrifaction species of Lepidocarpon were found to fail as bases of discrimination when 400 specimens of Lepidocarpon found in coal balls of Pennsylvanian age were studied. Measurements and observations made of a sample size of 136 of these 400 specimens reveal a degree of variation compatible with that of a single species. All previously described American and British petrifaction taxa fall within (or not significantly beyond) this range of variability of a single species as determined from this sample. Additional evidence concerning the 3-dimensional sporophyll structure of this one species of Lepidocarpon and the configurations obtained by certain planes of section through it have served to demonstrate that Illiniocarpon cadyi is in reality a taxon based on sectioned structures of the sporophyll of this Lepidocarpon species. Under the rules of priority, this species of Lepidocarpon and the following are assigned to Lepidocarpon lomaxi: Illiniocarpon cadyi, Lepidocarpon ioense, L. magnificum (megasporangiate form), L. crenatum and L. palmerensis. On the basis of the morphological evidence, the British petrifaction described as Lepidocarpon wildianum is also equated with L. lomaxi.  相似文献   

9.
Summary The operculate genus Chytridium Braun is emended and restricted to approximately 25 known species and several incompletely known members which lack an apophysis and develop much like species of Rhizophydium, insofar as the zoosporangium and absorbing or rhizoidal system are concerned, and form endobiotic or intramatrical resting spores. This interpretation corresponds fairly closely to Braun's diagnosis of the type species.A new genus, Diplochytridium, is established to segregate the former Chytridium species with an endobiotic or intramatrical apophysis or prosporangium and resting spores, which may develop sexually or asexually. Some of these species have a well-defined endo-exogenous alternation of growth and development in which the apophysis appears to function as a prosporangium. As interpreted here, Diplochytridium includes approximately 20 of the known species.Another new genus, Canteria, is created for a parasite of Mougeotia which Canter first described as a species of Phlyctidium but later found to develop endobiotic resting spores or zygospores by the fusion of conjugation tubes.  相似文献   

10.
During the study of the distribution of cellular slime molds in Swiss forest soils, three new species were isolated and studied in culture, namely, Dictyostelium fasciculatum, Dictyostelium polycarpum and Polysphondylium filamentosum. The first is cosmopolitan, the latter two are known only from Switzerland. Dictyostelium polycarpum is a very delicate species and is the first species reported which is restricted to a high altitude environment. It is characterized by a coremiform habit, reminiscent of D. polycephalum, and relatively long reniform spores. Dictyostelium fasciculatum is a larger species which resembles D. mucoroides in gross morphology but is much closer to Polysphondylium in its life cycle pattern and behavior. Polysphondylium filamentosum is only the third well-defined species of the genus to be described. It produces filamentose principal and lateral axes. Optimum temperature for all three is around 20 C, somewhat below that of most other species in the family.  相似文献   

11.
The literature on cyatheaceous spore morphology relative to the presence of a perine layer is reviewed, and evidence based on a sodium-hydroxide assay is presented indicating that the outer scultpine layer in certain cyatheaceous spores is perine. Perine so defined characterizes Metaxya, paleotropical and certain neotropical species of Sphaeropteris, nearly all species of Alsophila, all species of Nephelea, and certain species of Trichipteris and Cyathea. It is lacking in Lophosoria, many species of Trichipteris and Cyathea, and all species of Cnemidaria. Two major patterns of spore number per sporangium in the family are reported. Lophosoria, Sphaeropteris, Trichipteris, Cyathea, Cnemidaria, and probably Metaxya are characterized by 64-spored sporangia, whereas most species of Alsophila and all species of Nephelea are characterized by 16-spored sporangia. The congruence of this generic distribution of sporangial-capacity types with Tryon's phyletic arrangement of cyatheaceous genera supports the naturalness of his system. The intrasporangial germination of spores retained in dehisced and dispersed sporangia supports the suggestion that decreased spore number per sporangium in Alsophila and Nephelea may relate to the role of the sporangia as dispersal units. The decreased number of spores per sporangium is associated with a trend toward increase in the number of sporangia per sores, with the highest known count approaching 1000 sporangia per sorus. The Alsophila-Nephelea evolutionary line has probably not been ancestral in the phylogeny of the more advanced groups of ferns.  相似文献   

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The second part of the publication is devoted to the Melamphaes species (family Melamphaidae), which are characterized by 20 and more rakers on the first gill arch, by seven soft rays in the ventral fin, by absence of a temporal spine, by 14–15 rays in the pectoral fin, and by 11 abdominal vertebrae. M. polylepis is characterized by circumtropical range (Atlantic Ocean, Indian Ocean, western and central Pacific Ocean). Newly described species M. falsidicus is described from the northern Atlantic Ocean, where it was sampled between 34°N and 58°N. Before, this species was defined as M. microps. Another newly described species, M. pachystomus, is described along the Peruvian Coast. M. macrocephalus is redescribed. This species inhabits the eastern tropical Pacific Ocean (approximately between 30°N and 23°S). One of the studied specimens of M. macrocephalus was characterized by larger body size (SL = 128 mm) than was described before for this species. M. leprus is known currently by single findings from the eastern tropical Atlantic Ocean (between 11°N and 4°S). This species was also found in the samples obtain in the Gulf of Guinea.  相似文献   

14.
Two new species of Amomum (Zingiberaceae) from Mizoram are described and illustrated: A. dampuianum and A. mizoramense. Photographs, a comparison with the allied species A. corynostachyum and A. hypoleucum, and a key to the species of Amomum known in Mizoram is also provided.  相似文献   

15.
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   

16.
The karyotypes of 24 species of the tribe Pipisini (Diptera: Syrphidae) are described and illustrated. Nearly all the species of Neocnemodon, Pipiza and Pipizella have 2n=8 chromosomes consisting of a short telocentric XY pair and three metacentric pairs increasing in relative length from long to very long. Pair II chromosomes in several Pipiza species have high metacentric to low submetacentric arm ratios. One Parapenium species is tentatively reported as having five pairs and another five or six pairs. The karyological evidence favours placing the tribe Pipizini in the subfamily Syrphinae rather than in the subfamily Milesiinae.  相似文献   

17.
Based on field investigations as well as morphological and molecular systematic studies we found a new species of Bothriospermum which can be easily distinguished from all other known congeneric species by its unlobed faucal appendages and very long styles. We conducted molecular phylogenetic analyses based on a combined dataset from nrITS, plastid rps16, trnL‐trnF and trnG‐trnS regions. The results indicated that the new species indeed belongs in Bothriospermum and that it is well separated from other congeneric clusters, but that the genus Bothriospermum is paraphyletic with Nihon and Thyrocarpus clusetered within it. As a result, Bothriospermum longistylum sp. nov. is described and illustrated here. A revised key to species of Bothriospermum and a distributional map are also presented.  相似文献   

18.
Viet Nam has a coastline of 3200 km with thousands of islands providing diverse habitats for benthic harmful algal species including species of Gambierdiscus. Some of these species produce ciguatera toxins, which may accumulate in large carnivore fish potentially posing major threats to public health. This study reports five species of Gambierdiscus from Vietnamese waters, notably G. australes, G. caribaeus, G. carpenteri, G. pacificus, and G. vietnamensis sp. nov. All species are identified morphologically by LM and SEM, and identifications are supported by molecular analyses of nuclear rDNA (D1–D3 and D8–D10 domains of LSU, SSU, and ITS1-5.8S-ITS2 region) based on cultured material collected during 2010–2021. Statistical analyses of morphometric measurements may be used to differentiate some species if a sufficiently large number of cells are examined. Gambierdiscus vietnamensis sp. nov. is morphologically similar to other strongly reticulated species, such as G. belizeanus and possibly G. pacificus; the latter species is morphologically indistinguishable from G. vietnamensis sp. nov., but they are genetically distinct, and molecular analysis is deemed necessary for proper identification of the new species. This study also revealed that strains denoted G. pacificus from Hainan Island (China) should be included in G. vietnamensis sp. nov.  相似文献   

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A morphological study of specimens collected by the author and a critical revision of the key herbarium collections revealed a new rather peculiar taxon of Alchemilla occurring in almost every region of the Middle Volga basin, Russia. This novelity is here described as A. schmakovii and images of the principal morphological features of this species are provided. The new species is compared with related species in A. sect. Alchemilla (e.g. A. micans) and sect. Plicatae (e.g. A. breviloba) based on morphological characteristics.  相似文献   

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