Centrohelid

Detail of radiating forked siliceous spines of Acanthocystis turfacea (Carter,1863) which have detached from the periplast under the pressure of the coverglass. A. turfacea is a centroheliozoon with tangentially layered siliceous scales and two types of forked radial siliceous spines, one short, the other long (both seen here). The radiating axopodia contain extrusomes (not seen in this image). Endosymbiotic zoochlorellae are visible in this image. From standing fresh water near Boise, Idaho.DIC.

This species has spines of two lengths and that fork at their extremity. It also frequently occurs, as in this case, with symbiotic green algae. Phase contrast micrograph.

Portrait of centrohelid heliozoan with thick wavy gelatinous mantle incorporating scales. Probably from a genus in the Raphidiophryidae Mikrjukov, 1996, probably Raphidiophrys. This species contains zoochlorellae. From stagnant freshwater pool near Boise, Idaho. I would like to thank Vasilij Zlatogursky of St. Petersburg University for his assistance in identifying this specimen. Brightfield..

Portrait of centrohelid heliozoan with thick wavy gelatinous mantle incorporating scales. Probably from a genus in the Raphidiophryidae Mikrjukov, 1996. This species contains zoochlorellae. From stagnant freshwater pool near Boise, Idaho. Phase contrast. I would like to thank Vasilij Zlatogursky of St. Petersburg University for his assistance in identifying this specimen.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins. Phase contrast.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. The arms are supported by microtubular axonemes which terminate on a central granule (centroplast) which can just about be seen here. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins. Differential interference contrast.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins - a good example of which is seen upper left. Phase contrast.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins. Phase contrast.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins. Phase contrast.

Raphidiophrys (rah-fid-ee-off-riss) is a centrohelid heliozoon. Like other centrohelids, it has thin untapering arms, which have prominent extrusomes. Distinguished from other genera because the cell is enclosed in a layer of loosely adhering boat-shaped scales with thickened margins. Phase contrast.

Portrait of Raphidiophrys, a centroheliozoon with siliceous scales but no radiating spicules. Axopodia bearing extrusomes are evident. The abundant scales obscure the details of the cell body in this image. Sometimes multiple individuals cluster. From fresh water pond near Boise, Idaho. Phase contrast.

Detail of siliceous tangential scales of Raphidiophrys showing characteristic "canoe" shape. From freshwater pond near Boise, Idaho. Oblique illumination.

Raphidiophrys, a centroheliozoon with siliceous scales but no radiating spicules. Axopodia bearing extrusomes are evident. The abundant scales obscure the details of the cell body in this image. Sometimes multiple individuals cluster. From fresh water pond near Boise, Idaho. Phase contrast.

Raphidiophrys elegans can be found either grouped in colonies or as solitary living individuals. In colonies, the disc-shaped spicules form elongate cone-shaped accumulations around the pseudopodia. In solitary living individuals the spicules are arranged more tangentially. The spherical nucleus is placed eccentrically. Usually with one contractile vacuole. Symbiotic algae are sometimes present. Differential interference contrast.

Raphidiophrys elegans can be found either grouped in colonies or as solitary living individuals. In colonies, the disc-shaped spicules form elongate cone-shaped accumulations around the pseudopodia. In solitary living individuals the spicules are arranged more tangentially. The spherical nucleus is placed eccentrically. Usually with one contractile vacuole. Symbiotic algae are sometimes present. A squashed specimen of Raphidiophrys elegans. At about 12:00 the contractile vacuole is visible and the sphaerical nucleus is at 3:00. The spicules are lie tangientially and not cone-shaped around the pseudopodia. From a bog pond near Konstanz, Germany. Differential interference contrast.

Raphidiophrys (raff-fid-ee-off-riss) viridis is a distinctive member of this genus. The individuals are arranged to colonies and the plasma of the cells bearing symbiotic algae. his specimen was collected in a bog pond near Konstanz, Germany. Differential interference contrast.

Raphidiophrys (raff- fid-ee-off-riss) intermedia is a solitary species of this genus. The disc-shaped spicules are arranged tangentially around the pseudopodia. In contrast to the similar Raphidiophrys elegans the spicules of Raphidiophrys intermedia are formed like staples in tangential view. The spherical nucleus is placed eccentrically. There are 2 - 3 contractile vacuoles. The body is often irregular and not perfect round. The individuals can often be coloured green by symbiotic algae or algae in food vacuoles. This specimen was collected in a pond near Konstanz, Germany and is coloured green, probably caused by symbiotic. The body is irregular and the extrusomes on the pseudopodia are evident. Differential interference contrast.

Detail of the siliceous scales of the centroheliozoan, Rraphidocystis lemani (Penard, 1904) Nicholls and Dürrschmidt, 1985. This species has straight tubular elements (one of these is clearly seen at one o'clock in this image) as well as shorter funnel-shaped elements and tangential plate scales.Collected from organically enriched sediments of slow-moving freshwater stream near Boise, Idaho. DIC

One of the elongate hollow scales that coats the surface of this centrohelid heliozoon. Whole scale viewed by transmission electron microscopy.

Detail of long radial trumpet-shaped siliceous spines of Raphidocystis tubifera (Penard, 1904). The periplast is composed of 3 types of siliceous elements: elliptical tangential plate scales, long radial trumpet-like scales and short, broad radial funnel-shaped scales. From slow flowing organically enriched freshwater stream near Boise, Idaho. DIC.

Raphidocystis tubifera (Penard, 1904), a centrohelid heliozoan. The periplast is composed of 3 types of siliceous elements: elliptical tangential plate scales, long radial trumpet-like scales and short, broad radial funnel-shaped scales. The latter two types are seen well in this image at the upper margin of the periplast. The tangential elements are difficult to see. The long axopodia and their extrusomes are visible on the viewer's right in this image. Although species identification rests on EM morphology of the tangential plate scales, the organisms in these images conform to the description of R. tubifera (Mikrjukov,K.A. Arch. Protistenkd. 147: 205-212). From slow flowing organically enriched freshwater stream near Boise, Idaho. Phase contrast.