Coleps amphacanthus Ehrenberg, 1833
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried, Purren pond, Mainau pond, Bussenried, Bündtlisried, Ulmisried, Mühlhalden pond
Phylogenetic tree: Coleps amphacanthus
Diagnosis:
- body asymmetrically 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
I find Coleps amphacanthus is 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 low 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 spines, 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.