Microworld

world of amoeboid organisms

Menu

Leptomyxa fragilis (Penard, 1904) Siemensma, 1987

Diagnose: Large amoeba, polypodial form usually covered with detritus; numerous small nuclei, each with 1-3 irregular shaped nucleoli; cytoplasm clear, sometimes with some small mineral grains and diatom frustules; subpseudopodia often broadly lobed with a deep incision between the lobes; several contractile vacuoles, which can grow large and sometimes melt together; no crystals; hyaloplasm at the anterior end, with eruptive bulges; hyaloplasm may run back along the sides, just as in Rhizamoeba-species.

Dimensions: My measurements 250-480 µm, nuclei 6.2-8.4 µm (Penard 5-7 µm); Penard (1890) gives as mean 180-300µm, but his stained mounts in the collection of the Natural History Museum in London contain three specimens with the following dimensions: 398, 403 and 456 µm.

Ecology: Fresh water. I found this species in sediment of a small forest stream near Epe (1980), the Netherlands.

Remarks: It is possible that this species is identical with L. reticulata. The photomicrographs 11 and 13 of Pussard (1976) resemble strikingly the specimens which I observed. However, I have never seen the flat plasmodium. This form is probably only  employed on agar. Both Pussard (1976) and Goody (1914) state that the nuclei of L. reticulata usually have one nucleolus. Penard has seen one, two and three nucleoli.
The number of nuclei are numerous. Penard speaks of several hundreds. I could see this in his stained slides in London. In one mount I could count more than two hundred nuclei. I have tried to count the number of nuclei in my specimens. I stained one amoeba with borax-carmine and counted more than 400 nuclei.
Remarkable are the large vacuoles, the largest reaching a diameter of 41 µm. In the London collection these large vacuoles were also visible.

Leptomyxa fragilis
Leptomyxa fragilis, after Siemensma, 1987
Leptomyxa fragilis
Leptomyxa fragilis, after Siemensma, 1987
Recent posts

Organic-walled species

Specimen with an optical cross-section of the peduncle (left) Organic-walled species Diagnosis: Multinucleated organic-walled monothalamous foraminifera. Test spherical to oval shaped, with a hyaline, flexible,

Read More »

Velamentofex tyrolensis

V. tyrolensis, two specimens Velamentofex tyrolensis Völcker and Clauß, 2020 April 2022, I found two specimens in a sample from the pond in Crailoo, Netherlands. I could

Read More »

Raphidiophrys spec. nov.

Raphidiophrys n. sp. Raphidiophrys n. sp. Diagnosis: Plate-scales canoe-shaped, elongated, with tapering, rounded poles, slightly curved upwardly. Light microscopically, these plate-scales show a clear rim;

Read More »

Lacogromia spec. Naardermeer

Lacogromia sp., Naardermeer, the Netherlands, 2022 (n=nucleus) Lacogromia sp. Six living specimens were found in an old sediment sample from a freshwater ditch in nature

Read More »

Sphenoderia rhombophora

S. rhombophora , after Bonnet, 1966 Sphenoderia rhombophora Bonnet, 1966 Diagnosis: Test hyaline, ellipsoidal, very slightly compressed. Fundus relatively narrow. Pseudostome largely truncated. Neck very

Read More »

Sphenoderia ovoidea

S. ovoidea , after Jung, 1942 Sphenoderia ovoidea Jung, 1942 Diagnosis: Shell with four layers of plate-scales. Distinguished from S. fissirostris by the ovoid tapering

Read More »

Sphenoderia truncata

S. truncata , after Van Oye, 1949 Sphenoderia truncata Van Oye, 1949 Diagnosis: Shell smooth and diaphanous, with usually pentagonal, sometimes hexagonal, inconspicuous plates. The

Read More »

Nebela gimlii

N. gimlii, from Singer and Lara, 2015 Nebela gimlii Singer and Lara, 2015 Diagnosis: Test wide pyriform or drop-shaped, laterally compressed, with a protruding narrow

Read More »

Sphenoderia, with granules

Overview Sphenoderia S. compressa S. fissirostris S. labiata S. lenta S. macrolepis S. minuta S. ovoidea S. rhombophora S. sphaerica S. splendida S. truncata

Read More »

Nebela overview

Nebela overview N. acolla N. aliciae N. aliciae N. barbata N. bohemica N. carinatella N. collaris N. flabellulum N. gimlii N. golemanskyi N. nebeloides N.

Read More »