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.