Vacuolaria virescens Cienkowski 1870

Most likely ID: n.a.

 

Synonym: n.a.

 

Sampling location: Ulmisried, Simmelried

 

Phylogenetic tree: Vacuolaria viresens

 

Diagnosis: 

  • body ovoid to elliptical, dorso-ventrally flattened, deformable
  • length 37–138 µm
  • numerous, disc-shaped chloroplasts, yellowish gree to bright green
  • sometimes a lipid droplet in posterior part
  • contractile vacuole apically
  • layer of spherical mucocysts below pellicle
  • elliptical nucleus below contractile vacuoles
  • one leading flagellum and one trailing flagellum of body length
  • eyespot absent
  • extrusomes absent
Vacuolaria-virescens
Vacuolaria virescens

I find Vacuolaria virescens very common, especially in spring. Then it can also sometimes come to mass developments.


The cells are usually ovoid in shape, as shown in fig. 1 a-c. However, an elongated swim shape can also be adopted (s. fig. 2 a-c and fig. 3 a-d). The highly refractile, spherical mucocysts (s. fig. 2 b) react very sensitively to the coverslip and burst quickly.


Vacuolaria virescens can be confused with Vacuolaria viridis and Goniostomum semen. However, Vacuolaria viridis is smaller (usually less than 40 µm) with a heart-shaped cell form while Goniostomum semen has clearly visible extrusomes.

Vacuolaria-virescens

Fig. 1 a-c: Vacuolaria virescens. L = 61 µm. A freely swimming specimen. Note the leading flagellum (LF) and the trailing flagellum (TF). CV = contractile vacuole, Nu = nucleus. Obj. 60 X.

Vacuolaria-virescens

Fig. 2 a-c: Vacuolaria virescens. L = 80 µm. An elongated, freely swimming specimen. Note the layer of spherical mucocysts (Mu) beneaths the pellicle. CV = contractile vacuole, LF = leading flagellum, Nu = nucleus, TF = trailing flagellum. Obj. 100 X.

Vacuolaria-virescens

Fig. 3 a-d: Vacuolaria virescens. L = 63 µm. A third, freely swimming specimen. Note the numerous, disc-shaped chloroplasts (Chl). Obj. 100 X.

Vacuolaria-virescens

Fig. 4 a-b: Vacuolaria virescens. Two focal planes of a squashed specimen. Note the highly refractive mucocysts (Mu) beneath the pellicle. The disc-shaped (Chl) have a diameter of 3.5–4.0 µm. CV = contractile vacuole, Nu = nucleus. Obj. 100 X.