Microworld

world of amoeboid organisms

Menu
Pyxidicula husvikensis

 

From Beyens & Chardez, 1997

Microcorycia husvikensis  Beyens & Chardez, 1997
See Pyxidicula husvikensis

Diagnosis: It mainly follows the subsequent description by Chardez (1999), which is more precise and detailed than the original description:
The upper test part is dome-shaped and has a yellowish tinting. A very delicate punctuation is visible at high magnification. The margin of the upper test part is divided into an external part and an internal part. The internal margin changes into a flexible, hyaline membrane, which spreads towards the periphery and forms a border around the upper test part. This membrane can fold up towards the centre as to reduce the diameter of pseudostoma. The upper test part of young individuals is hyaline and more pliable than with older ones.
The cell body is located as a spherical or oval mass in the test and is connected to the upper test part through fine ectoplasmatic epipodia of varying number (two or three). Pseudopodia are lobate. Cytoplasm is finely granulate. It contains numerous inclusions (excreta and glycogen granules) and a contractile vacuole. The cell is mononuclear. The nucleus contains a central nucleolus. The nucleus has a diameter of 2.4-3,0 µm.

Encystment: Two types of cysts have been found. The resting cyst is formed inside the test. It is completely spherical in shape and has a diameter of 24 µm. Cytoplasm is dense and opaque. It is surrounded by a smooth membrane. Moreover, the cell can change into the state of pre-encystment. In pre-encysted state, the membrane is rough and irregular; it is attached to a test point. Pre-encysted cytoplasm has a diameter of about 28 pm . The lower test part is folded towards the peristome centre. The margin of the upper test part can also be folded inwards for reducing the test opening.

Dimensions: diameter upper test part 32-35 µm, height 16-20 µm, diameter including the spread lower test part: 39-43 µm.

Ecology : Slightly alkaline lakes and ponds, vegetated by moss (Beyens &  Chardez 1997), moss (Chardez 1999). So far only known from the subantarctic island of South Georgia.

Remarks: What is striking with M. husvikensis is that the lower test part has only a small height compared with other Microcorycia species. Thus it is assumed that the pseudostoma cannot be completely closed. Obviously M. husvikensis is a primordial form of Microcorycia.

All from Badewitz, 2004
Recent posts

Arcella marginata

Arcella marginata, after Deflandre, 1929 Arcella marginata Daday, 1905 Diagnosis: Shell roughly hemispherical, rather overhanging, with a flattened, smooth edge. In dorsal view showing a

Read More »

Arcella lobostoma

Arcella lobostoma, after Deflandre, 1929 Arcella lobostoma Deflandre, 1929 Diagnosis: Shell hemispherical. In ventral view, irregular circular outline, often a little elliptical; pseudostome irregularly lobed:

Read More »

Pelomyxa video

Pelomyxa palustris Pelomyxa palustris, found below decaying leaves in the hollow of a beech Pelomyxa palustris, found below decaying leaves in the hollow of a

Read More »

Hoogenraadia galeata

H. galeata – from Stepanek, 1963 Hoogenraadia galeata  (Stepanek, 1963) n. comb. Gillardella galeata Stepanek, 1963 Diagnosis: Shell somewhat similar to the shell of Corythion dubium

Read More »

Arcella grospietschi

Arcella grospietschi, after Stepanek, 1963 Arcella grospietschi  Stepanek, 1963 Diagnosis: Shell disc-shaped, yellow-brown, in ventral view with a undulated border, with seven large and seven smaller

Read More »

Arcella oyei

Arcella oyei, after Stepanek, 1963 Arcella oyei  Stepanek, 1963 Diagnosis: In dorsal view, the shell is circular, with 10 apparent broken lobes on the surface. In

Read More »