Microworld

world of amoeboid organisms

Menu
Massisteria spec. Fresh water; cilia are arrowed

Genus Massisteria Patterson & Fenchel, 1990

Diagnosis: small body, usually under 5 µm, which in trophic organisms emits curving, sometimes branched fine pseudopodia with extrusomes, and have two cilia lying inactive over the body surface. Under some circumstances, the arms may be resorbed and the organism will swim actively. Trophont does not move actively, feeds usually on bacteria. Multicellular forms are encountered.

Type species: Massisteria marina Larsen and Patterson, 1990

Remarks: This genus has only been reported from marine sites all over the world, but recently (2012) I found specimens in moist-chamber-mounts from fresh water samples (see the photomicrographs here) which closely resemble Massisteria. These specimens seem to live inside a kind of shell which is hard to detect light microscopically. Probably they represent a Microcometes species. The resemblance between Massisteria and Microcometes has also been noted by Lee et al (2005). The only difference at light microscopic level is the presence of a shell in Microcometes.
Specimens of Massisteria are light microscopically very similar to Limnofila. The only distinction seems to be the presence or absence of the two cilia.

Massisteria marina Larsen and Patterson 1990

Diagnosis: Organism with an irregular star-shaped body from which radiate thin pseudopodia with extrusomes. There are 2 inactive flagella. The organism is normally sedentary but, under adverse conditions, the arms are resorbed, the flagella become active, and the organism becomes a motile non-feeding flagellate.

Remarks: This small phagotrophic protist is associated with sediment particles and with suspended detrital material in littoral and oceanic marine waters. It has been found at sites around the world.

Literature: Patterson, D. J. and Fenchel, T.: Massisteria marina Larsen and Patterson 1990, a widespread and abundant bacterivorous protist associated with marine detritus. – Marine ecology progress series. Oldendorf  Vol. 62, no. 1-2, pp. 11-19. 1990.

Recent posts

Centropyxis tropica

C. tropica, after Deflandre, 1929 Centropyxis tropica  Deflandre, 1929 Basionym: Centropyxis aculeata var. tropica Deflandre, 1929 Diagnosis: As for C. aculeata, but with much longer

Read More »

Centropyxis nauwercki

Centropyxis nauwercki, after Schönborn, 1975 Centropyxis nauwercki  Schönborn, 1975 Diagnosis: Shell divided by a ring groove into a highly convex, balloon-shaped fundus part and a

Read More »

Centropyxis pontifera

Centropyxis pontifera, after Bartos, 1963 Centropyxis pontifera  Bartos, 1963 Diagnosis: Test large, broadly oval, formed of a thick, solid, brownish-yellow organic matter. Test with many

Read More »

Centropyxis pyriformis

Centropyxis pyriformis, after Van Oye, 1958 Centropyxis pyriformis  Van Oye, 1958 Diagnosis: This species is distinguished from C. aculeata by its narrowed shape towards the

Read More »

Centropyxis dentistoma

Centropyxis dentistoma, after Decloitre, 1949 Centropyxis dentistoma  Decloitre, 1949 Basionym: Centropyxis aculeata var. dentistoma Decloitre, 1949 Diagnosis: Pseudostome lobed, with 4 to 7 sharp teeth,

Read More »

Centropyxis compressa

Centropyxis compressa, after Van Oye, 1948 Centropyxis compressa  Van Oye, 1948 Diagnosis: Test a little elongated and very flattened regularly, like that of Arcella discoides;

Read More »

Centropyxis lata

Centropyxis lata, after Jung, 1942 Centropyxis lata  Jung, 1942 Diagnosis: Shell coarse-scaled, covered with a mix of diatoms and detritus; pseudostome large, ventral side mostly

Read More »

Centropyxis aurita

Centropyxis aurita, after Laminger, 1973 Centropyxis aurita  Laminger, 1973 Diagnosis: In ventral view, the shell is more or less broadly ovoid in outline. Quite straight truncated

Read More »

Centropyxis grelli

Centropyxis grelli, after Laminger, 1973 Centropyxis grelli  Laminger, 1973 Diagnosis: Shell covered with relatively large mineral particles. The pseudostome outline is formed by two convex arches.

Read More »

Centropyxis adami

Centropyxis adami, after Laminger, 1971 Centropyxis adami  Laminger, 1971 Diagnosis: In ventral view, the outline of the shell is more or less elliptical, in side

Read More »