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Pleurosigma (ploo-row-sig-ma) and Gyrosigma are two rather similar genera of sigmoid-shaped pennate diatoms found in intertidal sediments, salt marshes and so on. The nucleus is located at the centre of the cell. The plastids contain chlorophylls a and c which gives the yellowy-brown colour. This picture is taken of the surface of one of the valves and shows the raphe that is used in locomotion, and shows the plastids. Refractile globules are said to be the storage products from excessive photosynthesis. Pleuosigma is distinguished in part by the angled pattern of marks on the valve of the frustule. Differential interference contrast.
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Loxophyllum (locks-o-file-um) is one of several genera of flat gliding predatory ciliates. It glides along the substrate, exploring detritus with the anterior convex margin - which is where the mouth is located. There are rod-shaped extrusomes lying just under the cell membrane and in some species in prominences along the margins of the cell - not well developed in this cell. The extrusomes can be discharged to kill potential prey - usually other ciliates. Surface view of slightly squashed cell shows the surface folds where the rows of cilia (kineties) are located. Differential interference contrast.
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Loxophyllum setigerum, var. armatum. a,b,c: ventral, dorsal, and lateral aspects.
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Lionotus fasciola.
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Pleurosigma (ploo-row-sig-ma) and Gyrosigma are two rather similar genera of sigmoid-shaped pennate diatoms found in intertidal sediments, salt marshes and so on. The nucleus is located at the centre of the cell. The plastids contain chlorophylls a and c which gives the yellowy-brown colour. . Pleuosigma is distinguished in part by the angled pattern of marks on the valve of the frustule. Differential interference contrast.
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Loxophyllum (locks-o-file-um) is one of several genera of flat gliding predatory ciliates. It glides along the substrate, exploring detritus with the anterior convex margin - which is where the mouth is located. There are rod-shaped extrusomes lying just under the cell membrane and in some species in prominences along the margins of the cell - not well developed in this cell. The extrusomes can be discharged to kill potential prey - usually other ciliates. Phase contrast.
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Pleurosigma (ploo-row-sig-ma) and Gyrosigma are two rather similar genera of sigmoid-shaped pennate diatoms found in intertidal sediments, salt marshes and so on. The nucleus is located at the centre of the cell. The plastids contain chlorophylls a and c which gives the yellowy-brown colour. . Pleuosigma is distinguished in part by the angled pattern of marks on the valve of the frustule. Differential interference contrast.
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Loxophyllum (locks-o-file-um) a predatory ciliate. It is flattened, and glides along the substrate, exploring detritus with the anterior convex margin - which is where the mouth is located. There are extrusomes just internal to the margin of the cell, and also in some species prominences along the margins of the cell - not well developed in this cell. The extrusomes can be discharged to kill potential prey - usually other ciliates. Common. Differential interference contrast.
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Pleurosigma (ploor-a-sig-ma) medium to large size pennate diatom, common in sediments. With browny coloured plastid located centrally, refractile globules are lipid inclusions. The cell is located within a shell (frustule) made of silica (glass) and the patterns of pores and strengthening elements is used to distinguish different taxa. Differential interference contrast.
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Phase contrast micrograph of living cell.
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Loxophyllum, a leaf-like predatory ciliate. The mouth lies along the convex side of the body. The convex side has a number of warts and each wart contains many extrusomes. Feeds on detritus and other protists. Phase contrast micrograph.
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This pennate diatom was found in a plankton tow from Nantucket Sound off Martha's Vineyard - Massachusetts, USA. Image by Jeffrey Cole and Micah Dunthorn.
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Loxophyllum. Cell observed in sandy and muddy marine sediments in the vicinity of Broome, Western Australia in September 2003. This image was taken using phase contrast optics. Â Â This work was supported by the Australian Biological Resources Study.
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Portrait (left side) of the rhabdophorine ciliate, Siroloxophyllum utriculariae (Penard,1922) Foissner,1995. Siroloxophyllum was erected as a new genus based on the "adoral bulge" which encircles almost the entire circumference of the cell, a single dorsolateral brush kinety and morphologically distinct right and left Dorsolateral kineties different from other somatic kineties. The strongly laterally compressed cell is lancet shaped in outline. The cell is slightly contractile and highly flexible. The rounded anterior end is curved dorsally. The posterior is bluntly tapered. The flat right side bears 13-20 longitudinal kineties. The left side has 3-8 prominent longitudinal ridges (seen here) bearing short cilia. The slit-like cytostome is located along the anteroventral edge. A hyaline band containing long rod shaped extrusomes borders the cell. There is a distinctive structure which looks like a helix or twisted cord bordering the entire edge of the cell except for a short length of the anterior dorsal end. This is best seen at the ventral anterior end in this image (viewer's left). The perpendicularly arranged peripheral extrusomes appear to anchor their exterior ends in this structure. There are two contractile vacuoles (seen here), the anterior one just ventral to the macronuclei and the posterior one located dorsally. A food vacuole is seen immediately posterior to the macronucleus here. The central macronucleus is bipartite. The inconspicuous micronucleus is located between the two parts of the macronucleus. S. utriculariae swims slowly, gliding gracefully over the substrate. Differentiated from the similar L. helus by absence of trichocyst warts along the dorsal surface. Most easily confused with Amphileptus species which lack the distinctive bordering cord-like structure described above except for a short part of the anterior ventral surface and also have an anterior kinetal suture (spica) on the right surface. S. utriculariae may also be confused with Litonotus species which usually have a single contractile vacuole and extrusomes limited to only part of the ventral surface. Collected from a freshwater dredge pond near Boise, Idaho October 2004. DIC.
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A somewhat contracted cell, extrusomes are evident as thin rods underlying the surface of the cell. Phase contrast microscopy.
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Portrait (right surface) of the rhabdophorine ciliate, Siroloxophyllum utriculariae (Penard,1922) Foissner,1995. Siroloxophyllum was erected as a new genus based on the "adoral bulge" which encircles almost the entire circumference of the cell, a single dorsolateral brush kinety and morphologically distinct right and left Dorsolateral kineties different from other somatic kineties. The strongly laterally compressed cell is lancet shaped in outline. The cell is slightly contractile and highly flexible. The rounded anterior end is curved dorsally. The posterior is bluntly tapered. The flat right side bears 13-20 longitudinal kineties. The left side has 3-8 prominent longitudinal ridges bearing short cilia. The slit-like cytostome is located along the anteroventral edge. A hyaline band containing long rod shaped extrusomes borders the cell. There is a distinctive structure which looks like a helix or twisted cord bordering the entire edge of the cell except for a short length of the anterior dorsal end. The perpendicularly arranged peripheral extrusomes appear to anchor their exterior ends in this structure. There are two contractile vacuoles. The central macronucleus is bipartite. The inconspicuous micronucleus is located between the two parts of the macronucleus (not seen here). S. utriculariae swims slowly, gliding gracefully over the substrate. Differentiated from the similar L. helus by absence of trichocyst warts along the dorsal surface. Most easily confused with Amphileptus species which lack the distinctive bordering cord-like structure described above above except for a short part of the anterior ventral surface and also have an anterior kinetal suture (spica) on the right surface. May also be confused with Litonotus species which usually have a single contractile vacuole and extrusomes limited to only part of the ventral surface. Collected from a freshwater dredge pond near Boise, Idaho October 2004. DIC.
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Portrait of Loxophyllum helus (Stokes, 1884, Penard, 1922) a rhabdophorine ciliate. The body is elongate and laterally compressed. The left side is sparsely ciliated and slightly domed the flat right side is more densely ciliated. Very flexible. Prominent trichocyst warts occur at intervals along the dorsal edge (seen well here). A narrow flattened band traversed by trichocysts runs along the entire ventral edge. The slit-like oral aperture is located on the anterior ventral edge. There is one posterior contractile vacuole. The macronucleus is bipartite flanking a small micronucleus. Preys on rotifers and other ciliates. Collected from freshwater pond near Boise, Idaho in June 2003. DIC optics.
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Portrait (right side) of the pleurostomatid ciliate, Siroloxophyllum utriculariae (Penard,1922) Foissner,1995. Siroloxophyllum was erected as a new genus based on the "oral bulge" which encircles almost the entire circumference of the cell, a single dorsolateral brush kinety and morphologically distinct right and left dorsolateral kineties different from other somatic kineties. The strongly laterally compressed cell is lancet shaped in outline. The cell is slightly contractile and highly flexible. The rounded anterior end is curved dorsally. The posterior is bluntly tapered. The flat right side bears 13-20 longitudinal kineties. The basal bodies of one of the perioral kineties are seen well here along the ventral (viewer's right) margin. The left side has 3-8 prominent longitudinal ridges bearing short cilia. The slit-like cytostome is located along the anteroventral edge. A hyaline band borders the cell. There is a distinctive structure which looks like a helix or twisted cord bordering the entire edge of the cell except for a short length of the anterior dorsal end. This is best seen at the anterior end in this image. The perpendicularly arranged peripheral extrusomes appear to anchor their exterior ends in this structure except in a short portion of the dorsal anterior edge where extrusomes and the string-like structure bordering the cell edge are absent. SEM studies suggest that all pleurostomatid ciliates have a string-like structure on the cell margin but in other genera this occupies 1/2 the cell circumference or less. There are two contractile vacuoles (seen here), the anterior one just ventral to the macronuclei and the posterior one located dorsally. The central macronucleus is bipartite. The inconspicuous micronucleus (seen here) is located between the two parts of the macronucleus. S. utriculariae swims slowly, gliding gracefully over the substrate. Differentiated from the similar L. helus by absence of trichocyst warts along the dorsal surface. Most easily confused with Amphileptus species which lack the distinctive bordering cord-like structure around most of its circumference and also have an anterior kinetal suture (spica) on the right surface. S. utriculariae may also be confused with Litonotus species in which the oral bulge is limited to the anterior end of the ventral side. Collected from a freshwater dredge pond near Boise, Idaho October 2004. DIC.
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Portrait of Loxophyllum helus (Stokes, 1884, Penard, 1922) a rhabdophorine ciliate. The body is elongate and laterally compressed. The left side is sparsely ciliated and slightly domed the flat right side is more densely ciliated. Very flexible. Prominent trichocyst warts occur at intervals along the dorsal edge (seen well here). A narrow flattened band traversed by trichocysts runs along the entire ventral edge. The slit-like oral aperture is located on the anterior ventral edge. There is one posterior contractile vacuole. The macronucleus is bipartite flanking a small micronucleus. Preys on rotifers and other ciliates. Collected from freshwater pond near Boise, Idaho in June 2003. DIC optics.
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The oral bulge of this genus extends from the anterior end around the circumference of the cell to the anterior part of the dorsal side stopping short of the anterior apex on the dorsal side. This feature is the main distinguishing feature of the genus. In other pleurostomatid genera the oral bulge, although similar in structure, extends no furthe than the posterior end of the ventral side. The oral bulge has the appearance of a helical structure or a two stranded string. The yellow arrow in this image indicates the oral bulge along the dorsal edge of the cell. It is likely that only the anterior portion of the oral bulge on the ventral surface opens during feeding. DIC.
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Portrait of Loxophyllyum, large pleurostomatid ciliate, which is highly laterally, compressed. Glides with ribbon-like movement over substrate. Oral region is slit-like and oriented to the right in this image. Wart-like aggregates of extrusomes are seen at intervals along the dorsal (left) surface. Macronucleus is multinodal in this species. Many species. This species, from standing fresh water near Boise, Idaho, has been preying on rotifers. Oblique illumination.
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(Originally described under the name Lionotus fasciola). a -- Anus al -- Pellicular alveoli cv -- Contractile vacuole M -- Mane, made up of a series of stronger cilia N -- Macronucleus ncl -- Micronucleus o -- Mouth p -- Pellicle P -- Peristome tr -- Trichocysts
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Portrait of the pleurostomatid ciliate, Loxophyllyum meleagris (Mueller,1773) Dujardin, 1841. Glides with ribbon-like movement over substrate. Oral region is slit-like and oriented to the right in this image. Wart-like aggregates of extrusomes are seen at intervals along the dorsal (left) surface. Macronucleus is multinodal in this species. From standing temporary fresh water puddlenear Boise, Idaho. Phase contrast illumination.