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1.
Vegetative cells and zoospores of Hormotilopsis gelatinosa Trainor & Bold, H. tetravacuolaris Arce & Bold, Planophila terrestris Groover & Hofstetter, and Phyllogloea fimbriata (Korchikov) Silva were examined by transmission electron microscopy. All cells had pyrenoids traversed by cytoplasmic channels. Zoospores were quadriflagellate and had essentially cruciate flagellar apparatuses. Scales were present on free-swimming zoospores. These features are essentially identical to those of Chaetopeltis sp. and are dissimilar to those of other described green algae. The new order Chaetopeltidales is created to accommodate the genera Chaetopeltis, Hormotilopsis, Planophila sensu Groover & Hofstetter, Phyllogloea, Dicranochaete, and Schizochlamys, organisms previously scattered among the orders Tetrasporales, Chloro-coccales, Chlorosarcinales, and Chaetophorales. Members of the order are closely related to the ancestral chlorophycean flagellate genus Hafniomonas, may be ancestral with respect to other Chlorophyceae, and may also be closely related to the ulvophycean order Ulotrichales.  相似文献   

2.
A new genus and two new species are described and compared with related algae. All were isolated from terrestrial habitats on Signy Island, South Orkney Islands, Antarctica. They are Signiosphaera multinucleata gen. et sp. nov. (Tetrasporales, Chlorophyceae), Chlamydocapsa lobata sp. nov. (Tetrasporales, Chlorophyceae) and Chloromonas palmelloides sp. nov. (Volvocales, Chlorophyceae).  相似文献   

3.
Ultrastructural investigations of the development and structure of pseudocilia in Tetraspora lubrica and Schizochlamys sp. have disclosed interconnections between cytoptasmic microtubules and pseudo-cilial basal bodies heretofore unreported. Connections between elements of the basal bodies and the proximal connecting fibers are also described. The possible significance of the interconnections in correlating structure and function of these organelles is discussed.  相似文献   

4.
The similarity among Tetraspora, Chlorosaccus, and Phaeosphaera, belonging to the Chlorophyceae, Xanlhophyceae, and, Chrysophyceae, adds to the concept of parallel evolution among algal classes. Not only are all 3 genera characterized by colonial organization, nonmotile vegetative cells embedded in a gelatinous matrix, but the genera are also found in the same habitat. Further, the characteristic pseudocilia of Tetraspora cells are also found in colonics of Phaeosphaera. Morphological features of pseudocilia of Tetraspora and the nature of papillae in Chlorosaccus are also presented.  相似文献   

5.
Zusammenfassung Gloeodendron catenatum (Thompson)Bourrelly stimmt mitGl. ramosum Korschikoff in allen wesentlichen Merkmalen überein und ist daher als eigene Art zu streichen. Gl. ramosum (inklusivecatenatum), das bisher nur aus der Sowjetunion und Nordamerika bekannt war, tritt auch in einem Becken des Botanischen Gartens in Wien auf und zeigt außer den schon angegebenen einige weitere charakteristische Merkmale; auch die Variationsbreite in der Form der Lager spricht für die Auflassung vonGl. catenatum. Chrysochaete britannica, die bei optimalen Lebensbedingungen — an einem Fundort in Wien in den Herbstmonaten — Schleimborsten mit Gallertgeißeln besitzt, kommt dort im Frühjahr mit sonst typisch ausgebildeten Lagern ohne Schleimborsten vor.
Summary Gloeodendron catenatum (Thompson)Bourrelly in all siginificant features is congruent withGl. ramosum Korschikoff and cannot be accepted as separate species. Gl. ramosum (Gl. catenatum included), which until now has been reported only from UdSSR and North America, also occurs in Vienna and shows some hitherto unknown characteristics. Variation in form of colonies also indicates abandonment ofGl. catenatum. Chrysochaete britannica, which under optimal conditions in Vienna during fall forms colonies with pseudocilia, during spring shows coenobia with all typical attributes, but without pseudocilia.
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6.
SUMMARY. The algal flora of the Rivers Hayle and Gannel. whieh drain copper and lead mining regions of Cornwall, are described and compared. Although fluctuations in the rarer members of the algal communities were observed, the dominant filamentous algae at most sites did not change over the year of study. Both the total algal abundance and the number of species were depressed at high metal sites. Associations of species that were evident in field samples were confirmed and correlated with water metal levels by principal component analysis. The close similarity between the flora of similar sites on the copper-polluted River Hayle and the lead-polluted River Gannei implies that the degree of metal pollution, rather than the polluting metal per se, determines the species present. All mine sites were characterized by a Microspora -community whereas a Zygnemales community of Spirogyra and Mougeotia species was typical of low metal pollution. Moderately polluted sites downsteam of the mines had an intermediate flora of Zygnemaies, Microsporales. Ulotrichales and gelatinous Volvocales and Tetrasporales species. No species could be said to invariably indicate metal pollution; the most abundant species at highly contaminated sites were also those with the widest distributions. Field samples of filamentous algae (mainly Spirogyra, Zygogonium, Mougeotia and Microspora species) contained metal concentrations several orders of magnitude greater than ambient levels. For copper and iron, both algal metal contents and concentration ratios (μg g-1 algae/μg ml-1 water) were positive functions of water metal levels, although algal iron appeared to plateau at water concentrations of about 1 mg ml-1. Algal lead concentrations, but not the concentration ratios, also were positively correlated with water lead levels. Thus, for these three metals, the algal metal contents were indicative of ambient conditions. In contrast, algal zinc concentrations were nearly constant and consequently the concentration ratios for this metal were inversely related to water levels. This result suggests that unlike the uptake of other metals, uptake of zinc by these aigae may be strictly regulated.  相似文献   

7.
A new green alga, Octosporiella coloradoensis, belonging to the order Tetrasporales, family Tetrasporaceae, is described from Colorado mountain lakes. Colonies are planktonic or attached, the latter often forming loosely aggregated colonial complexes, thus creating an irregularly shaped complex. Individual colonies are spherical and consist of eight subcolonies, with each subcolony having spherically arranged octads of cells. Each vegetative cell bears two pseudoflagella that extend well beyond the colonial sheaths. Cell division is by eleutheroschisis and may be synchronous or asynchronous. Daughter colony formation is apparently coenobic, with each cell in the octad forming new subcolonies of eight cells each. Zoospore formation may precede daughter colony formation but the flagella remain rigid and non-motile. Large akinetes form in response to nutrient depletion. These germinate to produce eight aplanospores which divide to reconstitute a typical colony of Octosporiella. Sexual reproduction was not observed.  相似文献   

8.
The ultrastructure of the vegetative cell and zoospore of Characiochloris acuminata Lee et Bold (Chlorangiellaceae, Tetrasporales, Chlorophyceae) is described.

The vegetative cell is distinctive in having numerous contractile vacuoles which are randomly distributed in the cytoplasm and visible through the fissures of the parietal chloroplast. A single pyrenoid, embedded in the chloroplast, is penetrated by cytoplasmic canals which are lined by the chloroplast envelope. The vegetative cell is attached to the substrate or host by two flagellar remnants (retained from the zoospore stage), each of which is ensheathed in a gelatinous tube through the cell wall at the cell base. The basal bodies are apparently abscissed from the flagellar shaft by a unit membrane which becomes continuous with the plasma membrane.

The zoospore is biflagellate, with the flagella equal in length, smooth and longer than the cell body. The flagellar sheath is characteristically undulate and the two flagellar bases are connected by a dense interflagellar fibre. The large nucleus has a conspicuously inflated nuclear envelope and the pyrenoid is similar to that of the vegetative cell.  相似文献   

9.
Polystoma fuscus n. sp. (Polystomatidae, Polystomatinae) is described from the urinary bladder of Pelobates fuscus (Pelobatidae) in Bulgaria. Its general morphology is similar to that of other members of the genus but distinguished from them by the underdeveloped hamuli similar to the larval hamular primordia. The new species is also differentiated from the members of the genera of the subfamily Polystomatinae described without hamuli.  相似文献   

10.
Cell wall structure and composition of fifty-one algae in the Volvocales, Tetrasporales, Chlorococcales, and Chlorosarcinales were investigated to determine the feasibility of using the presence of cellulose, wall fibers, and wall periodicity as taxonomic characters. Although members of the Volvocales consistently lack cellulose, the diversity of wall characters in the other orders discourages the use of these characters as taxonomic or phylogenetic criteria.  相似文献   

11.
Two new species of the genus Tolypella (Characeae)–T. boldii Sawa sp. nov. and T. canadensis Sawa sp. nov.–were discovered in Texas, U.S.A., and Ontario, Canada, respectively. The species are recognized as additional members to the section Acutifolia because of the small and conical branchlet end cell and the oospore with a single basal impression. However, they differ from all the members previously described in the genus by the frequent and unique development of a terminal antheridium at the fertile branchlet node. A new and unexpected chromosome number of n = 8 for the genus was determined in both species, which, renders additional support to the conclusion that they represent a new taxonomic group in the section. The plants are described in detail in order to clarify some important morphological features which have been loosely interpreted by previous workers. Relationships between the new species and other members of the section are analyzed.  相似文献   

12.
Primula melanantha (Franch.) C. M. Hu, a taxon known from a single location in the south‐west of Sichuan Province of China and with a long and confused taxonomic history, is described and illustrated. Its relationships with other members of subsection Maximowiczii of section Crystallophlomis are discussed, new keys are provided, and factors relevant to its successful cultivation are described.  相似文献   

13.
Meconopsis wilsonii subsp. orientalis Grey‐Wilson, Rankin & Wu, a new subspecies from north‐east Yunnan Province of China, is described and illustrated. Its relationships with other members of subsection Eupolychaetia, particularly M. wallichii, M. violacea and the other subspecies of M. wilsonii, are discussed.  相似文献   

14.
Simultaneous microsporogenesis is described for the first time in a grass, Streptochaeta spicata Schrad., a tropical Brazilian species that belongs in the early‐divergent subfamily Anomochlooideae. Microsporogenesis is successive in all other Poaceae examined so far, and most other members of the order Poales, to which grasses belong. The only other reports of simultaneous microsporogenesis in Poales are in Rapateaceae and some members of the cyperid clade (Juncaceae, Cyperaceae, Prionium and Thurnia). Among the graminids, Ecdeiocolea (the putative closest relative to Poaceae) is successive, as are Joinvillea, Flagellaria and all other Poaceae, indicating that the simultaneous condition is autapomorphic in Streptochaeta, though Anomochloa has yet to be examined. Anther wall development in Streptochaeta is of the reduced type, as also in another early‐divergent grass Pharus, though most other Poales, including most grasses, have the monocot type. In Streptochaeta, as in Pharus, the endothecium lacks thickenings, unlike other grasses that have a persistent endothecium with thickenings. The centrifixed anthers and nonplumose stigmas of Streptochaeta suggest entomophily.  相似文献   

15.
Hadrurus arizonensis is a large, long-lived species of North American desert scorpion with lengthy, stereotyped courtship behaviors that lead to sperm transfer via an external spermatophore. Courtship and mating behaviors in H. arizonensis and other members of the Iuridae family have not been described. H. arizonensis has reproductive behavior similar to that of other scorpions, including the promenade a deux, but with some unique components described here for the first time. Courtship and mating behaviors of H. arizonensis are presented in a flowchart to emphasize its stereotypical nature and suitability for experimental manipulation in field and laboratory studies.  相似文献   

16.
The sensitivity of the cell-free protein synthesis systems from Acidanus brierleyi, Acidianus infernus, and Metallosphaera sedula, members of the archaeal order Sulfolobales, to 40 antibiotics with different specificities has been studied. The sensitivity patterns were compared to those of Sulfolobus solfataricus and other archaeal, bacterial, and eukaryotic systems. The comparative analysis shows that ribosomes from the sulfolobales are the most refractory to inhibitors of protein synthesis described so far. The sensitivity results have been used to ascertain in phylogenetic relationships among the members of the order Sulfolobales. The evolutionary significance of these results are analyzed in the context of the phylogenetic position of this group of extreme thermophilic microorganisms. Correspondence to: R. Amils  相似文献   

17.
《Journal of bryology》2013,35(4):259-261
Abstract

Cheilolejeunea (subgen. Strepsilejeunea) norisiae G. Dauphin & Gradst. sp. nov. is described and illustrated. The new species differs from other members of the genus Cheilolejeunea by the laciniate leaf margins and the large pre-apical tooth.  相似文献   

18.
The spermathecae of 4 species of Microcoryphia (Lepismachilis targionii, Trigoniophthalmus alternatus, Machilis sp. and Machilinus rupestris) present characteristics related to the primitive phylogenetic position of these apterygote insects. They are paired organs situated in the 8th abdominal segment on each side of the rudimentary genital chamber. Each spermatheca includes 2 different tissues: (a) a simple epithelium surrounding 2 spermathecal capsules and communicating with the genital chamber by short ducts; (b) a complex glandular tissue composed of numerous functional units, each made up of several cell types — a large glandular cell with a subapical reservoir, 2 basal cells, a ductule cell and enveloping cells. One of the basal cells, called the ciliary cell, presents a dendrite-like process containing 2 apical centrioles in alignment. Several ductules of neighbouring units join together before opening in the genital chamber, independently of the ducts of the spermathecal capsules.The spermathecae undergo marked changes during moulting periods. Apolysis is followed by a partial dedifferentiation of the glandular cells, then the formation of new ductule cavities and the growth of a pseudocilium at the apex of the dendrite-like process of each ciliary cell. Afterwards, cuticular material is laid down around the pseudocilia, forming the intima of the new ductules, which results from the secretions of at least the ciliary and ductule cells. The pseudocilia degenerate before ecdysis. A comparison is made with the organogenesis of analogous organs described in different insect species.  相似文献   

19.
The small Asian genus Asiabregma Belokobylskij, Zaldivar & Maeto 2008 is recorded from China for the first time and one new species, A. achterbergi sp. nov., is described and illustrated. A key to species of genus Asiabregma is updated to include A. achterbergi. The relationship between Asiabregma and other members of the subtribe Facitorina and the systematic position of Facitorina are discussed.  相似文献   

20.
Summary We have used the polymerase chain reaction (PCR) to isolate a sequence characteristic of aTy1-copia group retrotransposon from the genome of the herring (Clupea harengus). This is the firstTy1-copia group retrotransposon sequence described in a vertebrate. Phylogenetic comparison of this sequence with other members of this group of retrotransposons shows that it resembles more closely some Tyl-copia group members fromDrosophila melanogaster than other group members in plants and fungi. These observations provide further evidence that theTy1-copia group LTR retrotransposons span many of the major eukaryote species boundaries, suggesting that horizontal transmission between different species has played a role in the evolution of this retrotransposon group.  相似文献   

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