Acanthocystida

Portrait of Acanthocystis aculeata HERTWIG & LESSER, 1874, a heliozoan with long thin radiating axopodia containing bead-like extrusomes and layered surface plates with shorter curved sharp projecting spines. This individual contains zoochlorellae. From freshwater pond near Boise, Idaho. Brightfield.

Whole mount preparation of the spine scale of this species. Transmission electron micrograph.

Transmission electron micrograph of a plate scale that coats the cell body.

Whole leaf scale, transmission electron micrograph.

Spine scale, whole mount, transmission electron micrograph.

Acanthocystis penardi (WAILES,1925).

Acanthocystis penardi (WAILES,1925).DIC.

Transmission electron micrograph of a whole spine scale.

Transmission electron micrograph of whole spine scales and plate scales.

Acanthocystis turfacea (a-can-tho-sis-tis tur- fats-ee-a), a centrohelid heliozoon. Body coated with a layer of flattened siliceous scales and spine scales. Spine scales are of two lengths, and forked at their apices. This sample from moss. Nucleating site for axopodia just about evident in the cell to the right. Differential interference contrast.

Acanthocystis turfacea (a-can-tho-sis-tis tur- fats-ee-a), a centrohelid heliozoon. Body coated with a layer of flattened siliceous scales and spine scales. Spine scales are of two lengths, and forked at their apex. This sample from moss. Differential interference contrast.

Acanthocystis turfacea (a-can-tho-sis-tis tur- fats-ee-a), a centrohelid heliozoon. Body coated with a layer of flattened siliceous scales and spine scales. Spine scales are of two lengths, and forked at their apices. Axonemes terminate on central granule or centroplast, shown here. This sample from moss. Differential interference contrast.

Acanthocystis turfacea (a-can-tho-sis-tis tur- fats-ee-a), a centrohelid heliozoon. Body coated with a layer of flattened siliceous scales and spine scales. Spine scales are of two lengths, and forked at their apices. This sample from moss. Differential interference contrast.

Acanthocystis turfacea (a-can-tho-sis-tis tur- fats-ee-a), a centrohelid heliozoon. Body coated with a layer of flattened siliceous scales and spine scales. Spine scales are of two lengths, and forked at their apex. The cytoplasm of this species contains often symbiotic algae. The body of this specimen measures 88 microns in diameter. This specimen was collected in a pond near Konstanz, Germany. Differential interference contrast.

Portrait of Acanthocystis turfacea (Carter, 1863), a centroheliozoon with tangentially layered siliceous scales and two types of forked radial siliceous spines (one short, the other long) and radiating axopodia with extrusomes, all visible in this image. Chlorella endosymbionts are present. From standing fresh water near Boise, Idaho. Brightfield.

Portrait of Acanthocystis turfacea (Carter,1863), a centroheliozoon with tangentially layered siliceous scales and two types of forked radial siliceous spines (one short, the other long) and radiating axopodia with extrusomes, all visible in this image. Detail of radiating forked siliceous spines of Acanthocystis turfacea. . From standing fresh water near Boise, Idaho.DIC.

Detail of long forked radiating siliceous spine of Acanthocystis turfacea (Carter,1863), demonstrating the typical circular baseplate. From standing fresh water near Boise, Idaho.DIC.

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.

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.

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 at 12 o'clock in this image. Zoochlorellae are seen in the cytoplasm. 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. Differential interference contrast.