Pyxidicula patens var.
Pyxidicula patens var., just after dividing

 

 

Pyxidicula patens var.

 

Diagnosis: Shell hemispherical, aperture nearly as large as the diameter of the shell; aperture bordered by a clear rim, which is a broadened extension of the shell wall; this rim has an alveolated structure; usually a hyaline veil is attached to the rim; it is usually curved inwards and strongly curved outwards and more or less undulated; nucleus single, spherical, with some dispersed spherical granules.

 

Dimensions: My measurements: 35-44 µm, nucleus c. 10 µm, but hard to see.

 

Ecology: freshwater, in Sphagnum from the Haaksbergerveen, and Kloosterhaar, the Netherlands. It was abundantly present in samples.

 

Remarks: This species differs from the nominal species by the structure and angle of its rim, which is thicker and not curved inward. The veil is large, seemingly hollow and often irregular shaped. It is difficult to imagine the real shape and structure of this veil. It is also hard to observe where this veil is attached to the shell. What looks like a flat broad rim, is in fact a wide depressed tubular ring. 
All photomicrographs on this page show cells from the same sample.

 

Pyxidicula patens var.
Pyxidicula patens var.
Pyxidicula patens var., with pseudopodia (left) and hyaline fringe
Pyxidicula patens var.

 

 

Cross section of the shell, with the collar marked by arrows.
Pyxidicula patens var.
Pyxidicula patens var.
Living cell, lateral view, and shell, with nucleus (arrow)
Pyxidicula patens var.
Pyxidicula patens var.
Living cell, lateral view, with smooth veil; the rim or collar has an alveolated structure (arrow)
Pyxidicula patens var.
Pyxidicula patens var.
Rim, with alveoli and veil
Pyxidicula patens var.
Pyxidicula patens var.
Rim with alveoli and veil and shell without pronounced collar and without veil
Pyxidicula patens var.
Structure of a shell