Epipyxis utriculus var. acuta

(J. Schiller) D.K. Hilliard & Asmund, 1963

Most likely ID: n.a.

 

Synonym: Dinobryon utriculus var. acutum

 

Sampling location: Simmelried

 

Phylogenetic tree: Epipyxis utriculus var. acuta

 

Diagnosis: 

  • lorica spindle-shaped, aperture contricted
  • length 20–28 µm, width 5–7 µm (of lorica)
  • lorica composed of disc-shaped scales (hard to see)
  • tapered end of lorica with disc-shaped holdfast
  • cells spindle shaped
  • one chloroplasts with stigma
  • one contractile vacuole near mid-body
  • cells solitary
Epipyxis-utriculus-var-acuta
Epipyxis utriculus var. acuta
So far, I have found Epipyxis utriculus var. acuta only very rarely and exclusively in the Simmelried. There, I mostly find the specimens on algal filaments, which are often densely colonized (s. fig. 1).

Epipyxis utriculus var. acuta can be recognized by the typical shape of its lorica. It somewhat resembles an ice cream cone, with the front third slightly narrowed. The evenly tapering rear part of the shell ends in an adhesive disc, with which the specimens attach themselves to the substrate. The lorica is assembled of very delicate, round scales that can only be seen with staining or in phase contrast (s. drawing 2 above). In DIC, these scales are difficult to visualize (s. fig. 4).

The cells are spindle-shaped, with the hyaline posterior end being difficult to see because it tapers almost thread-like. The cell is attached to the bottom of the lorica. There is only one chloroplast, topped by a small eyespot (s. fig. 3). The cells have two flagella of different lengths, and the contractile vacuole is located near the middle of the body (s. fig. 2).
Epipyxis-utriculus-var-acuta

Fig. 1: Epipyxis utriculus var. acuta. Some specimens on an algae filament. Obj. 100 X.

Epipyxis-utriculus-var-acuta

Fig. 2: Epipyxis utriculus var. acuta. A specimen in detail. The contractile vacuole (CV) is located near mid-body. Obj. 100 X.

Epipyxis-utriculus-var-acuta

Fig. 3: Epipyxis utriculus var. acuta. Two specimens on an algae filament. The eyespot (ES) is also called stigma and located at the anterior end of the chloroplast. The flagella (F1, F2) habe different length. In the center of the cell probably the nucleus (Nu?) is visible. LB = leukosine body. Obj. 100 X.

Epipyxis-utriculus-var-acuta

Fig. 4: Epipyxis utriculus var. acuta. A highly contrasted image to visualize the disc-shaped scales (arrow) that make up the lorica. Obj. 100 X.