Monommata grandis (Tessin, 1890)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Simmelried


Phylogenetic tree: Monommata grandis



  • body elongate ovate
  • length 350–530 µm (with toes)
  • corona slightly oblique
  • lorica with distinct longitudinal striation
  • one eye spot at posterior end of ganglion
  • two reddish blisters between intestinum and bladder
  • stomach and intestine colored golden brown or orange
  • foot very short and stout
  • toes extremely long and unequal (150–400 µm long)
Monommata grandis

I only find Monommata grandis in the Simmelried where the species is quite common. I mainly find specimens between floating plant masses. In the sample vessel they gather at the surface.

Monommata grandis is particularly easy to identify among the various species of the genus Monommata because it has some characteristics that are unique to this species. For example, Monommata grandis has an eyespot, which is located at the posterior end of the ganglion (s. fig. 3). The lorica is clearly longitudinally striated (s. figs. 1 b and 2 b) and between the intestine and the bladder is a pair of reddish blisters is located whose function is unknown (s. figs. 1 b, 1 c, 2 a and 3). At higher magnification it can be seen that these reddish blisters contain a central, reddish oil body (s. fig. 3). They could be glands that produce a reddish secretion. The stomach and intestines are always golden brown or orange in color. This was the case with all the specimens I examined. The two extremely long toes are of different lengths and contain striated muscle cells. With the help of these toes, Monommata grandis can perform jumps quickly.


Fig. 1 a-c: Monommata grandis. L = 455 µm (with toes). A freely swimming specimen from left (a, b) and from dorsal. Note the longitudinal strination of the lorica (b) and the pair of reddish colored blisters (RBL) located between intestine and bladder (BL). Obj. 40 X.


Fig. 2 a-b: Monommata grandis. Two focal planes of a slightly squashed specimen. Note the reddish blister (RBL) and the longitudinal striation (LS) of the lorica. Obj. 60 X.


Fig. 3: Monommata grandis. A strongly squashed specimen from right. ES = eyespot, INT = intestine, RBL = reddish blister, ST = stomach, TR = trophi, Vit = vitellarium. Obj. 60 X


Fig. 4 a-b: Monommata grandis. Two focal planes of the trophi in a strongly squashed specimen. Obj. 40 X.