Coleps amphacanthus (Ehrernberg, 1834)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Simmelried, Purren pond, Mainau pond, Bussenried, Bündtlisried, Ulmisried, Mühlhalden pond


Phylogenetic tree: Coleps amphacanthus



  • body asymmetrical sac-shaped, sometimes barrel-shaped
  • length 70–90 µm
  • 3 posterior spines
  • 4 anterior spines
  • uniform ciliation
  • 24–28 longitudinal rows of plates
  • “windows” in armour pretzel-shaped
  • anterior main plate with 5 “windows”
  • posterior main plate with 4 “windows”
  • 4–8 caudal cilia
  • macronucleus spherical in mid-body
  • apical mouth opening with basket of pharyngeal trichites
  • contractile vacuole subterminal
Coleps amphacanthus

I find Coleps amphacanthus very common in almost all of my sampling locations. This member of Coleps is slightly larger than the other Coleps species and is conspicuous by its sac-shape, even at small magnifications. Furthermore, this species has 4–8 caudal cilia (s. figs. 1 a and 2 b). The windows in the armour are pretzel-shaped as in Coleps hirtus. However, Coleps amphacanthus has 5 windows in the anterior main plate and only 4 windows in the posterior main plate (s. fig. 4 a) while Coleps hirtus has only 4 windows in each of the two main plates.


Coleps amphacanthus is a scavenger that quickly gathers on dead or injured protozoans or metazoans. This process is probably controlled by chemotaxis, with Coleps amphacanthus following the concentration gradient to the prey.


Fig. 1 a-d: Coleps amphacanthus. L = 85 µm. A freely swimming specimen. AS = anterior spiones, CC = caudal cilia, Ma = macronucleus. PS = posterior spines. Obj. 40 X.


Fig. 2 a-b: Coleps amphacanthus. L = 83 µm. A second freely swimming specimen. CC = caudal cilia. Obj. 40 X.


Fig. 3 a-c: Coleps amphacanthus. L = 80 µm. Different focal planes of a slightly squashed specimen. CC = caudal cilia. Obj. 60 X.


Fig. 4 a-b: Coleps amphacanthus. Two focal planes of the armour in a strongly squashed specimen. The anterior main plate has 5 “windows” (1–5) while the posterior main plate has only 4 “windows” (1–4). The windows are pretzel-shaped (arrows). Obj. 100 X.