Locomotive form variable, usualy it is wider in the anterior part,
sometimes the cell looks like an irregular triangle
with anterior hyaline border. The cell sometimes forms short, wide
conical pseudopodia. No differentiated uroid in most cells, in some -
wide plicate uroid.
Length in locomotion 90-140 mkm (average 111 mkm), L/B about 1.2 - 1.5.
Single spherical nucleus, about 6 mkm in diameter,
with central endosome about 3 mkm in diameter.
One contractile vacuole. Many small irregular cristals in the cytoplasm.
No cysts found.
Cell coat is a "cuticle" (Page, 1988), about 320 nm in thickness.
It consits of three distinct layers of fibrillar matrix. Most close to
the membrane layer consists of fine fibrills, parallel to the cell
surface, its total thickness is about 110 nm. Over it is a layer, consisting of
vertical prismatical elements, about 50 nm in length. The outer layer
looks amorphous, its thickness is about 50 nm.
Dictyosomes are not numerous, consist of 3-7 cisternae.