world of amoeboid organisms

Leptophrys vorax
Leptophrys vorax, engulfing a diatom


Leptophrys vorax (Cienkowski, 1865) Zopf, 1885

Diagnosis: Trophozoites extremely variable in shape and continuously changing the outline; usually flattened and spreading on surfaces. Small advancing individuals sometimes compact. Intermediate-sized cells can show a fan-like outline, can be branched into several arms, or elongate; sometimes drawn out to considerable length, then appearing as two cell bodies just connected via a thin, tense cytoplasmic stand. Due to adhesion on the substrate, moving organisms produce sticky tails, which stretch and finally are retracted. Size extremely variable, ranging from circa 40 µm to over one millimeter; clear distinction between single trophozoites and plasmodia is not possible. Pseudopodia are predominantly produced at the edges of the cell, often originating from a hyaline and very delicate fringe of cytoplasm; sometimes in tufts. Pseudopodia long and thin, tapering, mostly unbranched; dendritic structures and anastomoses occur. No membranosomes present on the pseudopodia. Pseudopodial accumulation indicates direction of cell movement or cell extension, sometimes occurring on several sites in an individual. Coloration of the central cell body ranges from colorless to orange, depending on food source and contraction of the cell body; cell periphery and pseudopodia colourless. Cytoplasm often contains numerous vacuoles, several are contractile; vacuolation sometimes obscured due to numerous tiny refractive granules, but clearly visible at high magnification and in expanded individuals. At least two different populations of cytoplasmic granules distinguishable: colorless granules, possibly corresponding to the membranosomes of Vampyrella. Orange granules, possibly lipid droplets containing dissolved carotenoids of the prey. Numerous nuclei; very inconspicuous, often not visible in living individuals, but appearing as vesicular structures (about 3.5 µm in diameter) in squeezed dying cells. Cells move very smoothly over surfaces accompanied by the occasional retraction of the sticky posterior ends. When food is scarce trophozoites can transform into the isodiametric morphotype, detach and float in the water column. These compact cells, about 30 µm in diameter, resemble Vampyrella due to their radiating pseudopodia.
Due to plasmodial organization of unfused trophozoites, difficult to distinguish from the latter; very large plasmodia can exceed one millimeter. Digestive cysts. Cysts vary greatly in size and shape depending of type and amount of prey. The smallest cysts are elliptical or roundish and about 30 mm in size, whereas large cysts can reach several hundred microns in length. Larger cysts can be elongated, irregular lobed, or dumbbell-shaped; when single large algal cells are engulfed, the cyst outline resembles the prey, as shown in case of banana-shaped cysts containing Closterium sp. or very slender cysts containing Synedra sp. The digestive cysts exhibit only one tight fitting cyst envelope, with even surface; corresponding to the inner cyst envelope of Vampyrella. Young stages reveal the green algal prey in the centre of the cell surrounded by colorless or slightly orange cytoplasm, in older stages the ingesta turned brown. During hatching of the trophozoites the food remnants are left behind in the empty cyst envelope. Although internal cell division occurs, the daughter cells occasionally fuse again outside of the cyst envelope during hatching. No resting cysts observed.

Ecology: Fresh water and soil. Observed food organisms: Cylindrocystis brebissonii, Closterium cornu, Closterium sp., Planotaenium interruptum, Saccharomyces cerevisiae, several diatoms and fragments of filamentous algae.

Remarks: Trophozoites engulf whole prey cells during their movement, often resulting in several food items collected in the cytoplasm of an individual. The occasionally observed change in colour of the prey indicates ongoing digestion before entering the immobile cyst stage.

Source: Hess et al, 2012


Cienkowski Leptophrys vorax
These are the original drawings of Cienkowski, put together with new but original numbers:
14: reticulum
15-16: Verdauungscysten
17: two individuals leave the cyst.


Leptophrys vorax
Leptophrys vorax, c. 125 µm – Southern France, fast stream near Grimaud
a trophozoit
b cyst
c empty cyst


Leptophrys vorax
Leptophrys vorax, cyst with two different kind of diatoms
Leptophrys vorax
Leptophrys vorax, two cells in a cyst, just before leaving.
Leptophrys vorax
Leptophrys vorax, leaving its cyst
Leptophrys vorax
Leptophrys vorax, with cyst on the outer surface of an empty cyst
Leptophrys vorax
Parasites on Leptophrys vorax
Leptophrys vorax
Recent posts

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 »

Centropyxis halophila

C. halophila, after Bonnet, 1959 Centropyxis halophila Bonnet, 1959 Diagnosis: Shell with ovoid sole, extended by a rather strongly covering visor and not clearly separated

Read More »

Euglypha cuspidata

Euglypha cuspidata Euglypha cuspidata  Bonnet, 1959 Diagnosis: Shell small, very transparent, ovoid, in lateral view very elliptical, with sharp edges. Pseudostome small, elliptical, surrounded by a

Read More »