Phialina caudata
(Kahl) Wang, Ji & Yin, 2019
Most likely ID: n.a.
Synonym: Lacrymaria caudata
Sampling location: Simmelried
Phylogenetic tree: Phialina caudata
Diagnosis:
- body cylindical or pouch-shaped with pointed tail
- length 80–170 µm, width 20–45 µm
- macronucleus ovoidal
- micronucleis ovoidal or spherical
- extrusomes straight rods
- contractile vacuole subterminal
- 20–24 somatic kineties
So far, I have only found a single specimen of Phialina caudata in July 2007 in the Simmelried. I have no further records to date.
Originally, the species was described as Lacrymaria caudata by Kahl (1933). His description is extremely brief, only 2 lines long, but he provided two drawings (s. drawings above). The species was then transferred to the genus Phialina by Wang, Ji & Yin (2019). The genus Phialina is characterized by a non-contractile neck.
The main features of Phialina caudata are the pointed posterior end, the ovoid macronucleus, and the subterminal contractile vacuole. Kahl reported a length of 80–100 µm, while Wang, Ji & Yin reported 80–170 µm.
The very similar species Phialina vertens has a broader head and is somewhat smaller (60–85 µm). Additionally, the number of somatic kineties is lower at 18–20 compared to Phialina caudata, which can only be recognized after silver impregnation.
Fig. 1 a-d: Phialina caudata. L = 84 µm. A freely swimming specimen. CV = contractile vacuole, Ma = macronucleus. Obj. 60 X.