Microworld

world of amoeboid organisms

Menu
Acanthocystis dresscheri

Acanthocystis dresscheri  Siemensma & Roijackers, 1988

Diagnosis: Cell diameter 20 µm. Spine-scales 7.3-10.3 µm long, with a straight, cylindrical, hollow shaft, 0.5 -0.7 µm in diameter, centrally set on a circular basal plate. The apex of the shaft is slightly expanded, 0.6-0.8 µm in diameter, with 5-8 marginal sharply pointed teeth, each ca. 0.13 µm long. The basal plate is 1.4-2.2 µm in diameter, flat, with an upwardly bent rim, ca. 0.14 µm thick. The plate-scales are 4.7-5.5 x 2.3-3.0 µm, having concave sides with the median constriction 1.5-2.4 µm wide; the upper surface is ornamented with a distinct pattern of numerous small granules, more or less irregularly distributed, sometimes arranged in concentric rows; central area smooth with a slight indication of a longitudinal thickening. The lower surface is smooth with a protrusive axial rod-shaped thickening, distinctly separated from the scale surface and only at both ends merging into the scale. The protrusion is 0.43 µm thick and ca. 1.3 µm long.

Remarks: The protrusion on the lower side of the plate-scales is the most remarkable feature of this species. A. dresscheri shows some similarity with A. longiseta Penard, 1901, diagnosed as having rod-like or irregular plate-scales (Penard, 1904). It is not unlikely that Penard mistook the rod-like protrusion, present in plate-scales of A. dresscheri, for the whole plate-scale, as indicated by Siemensma (1981: plate 41 E, F). The main distinction between these two species is the presence of spine-scales of the same length (A. longiseta) and of short and long spine-scales (A. dresscheri). The diagnosis of A. longiseta was changed by Penard (1905 a, b), by describing the plate-scales as elliptical and without any longitudinal thickening, which indicates the problems of distinguishing among species by light microscopy.
A. dresscheri has been recognised in samples taken from a moorland pool (pH 5.5) near Nunspeet, the Netherlands. The samples are from the collection of the late Mr. Th. Dresscher, who identified the specimens as Acanthocystis penardi, not knowing the characteristic ultrastructure. Siemensma (1981) collected this species from similar locations in the Netherlands, but included A. dresscheri in his LM-description of A. penardi.

Recent posts

Penardochlamys arcelloides

P. arcelloides – from Penard, 1904 Penardochlamys arcelloides  (Penard, 1904) Deflandre, 1953 Diagnosis: Colorless or very slightly yellowish envelope, bag or cauldron-shaped, very thin, chitinous,

Read More »

Reticulomyxa hannae

R. hannae, plasmodium – photomicrograph Steffen Clauss Reticulomyxa hannae Völcker and Clauß, 2020 Diagnosis: Trophozoites surrounded by a very thin mucous envelope, with slowly moving plasmodia, variable

Read More »

Velamentofex saxonensis

V. saxonensis, feeding (photomicrograph Steffen Clauss) Velamentofex saxonensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 30-95 μm, granuloreticulopodia up to 1000 μm long. with a hyaline, thin

Read More »

Velamentofex tyrolensis

V. tyrolensis (photomicrograph Steffen Clauss) Velamentofex tyrolensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 98-125 μm, with reticulopodia up to 300 μm long, with a hyaline,

Read More »

Velamentofex berolinensis

V. berolinensis Velamentofex berolinensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 50-300 µm, with a hyaline, extremely flexible, membranous test. Nuclei numerous, 11.6-16.2 µm in diameter,

Read More »

Lieberkuehniidae

 Lieberkuehniidae  Siemensma, Holzmann, Apothéloz-Perret-Gentil, Clauß, Voelcker, Bettighofer, Khanipour Roshan, Walden, Dumack and Pawlowski, 2020 Diagnosis: Multinucleate organic-walled monothalamous foraminifera. Test very flexible, elongated to broadly

Read More »