Phialina pupula
(Müller, 1773) Foissner, 1983
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried, Pond behind parking space St. Ulrich (Austria)
Phylogenetic tree: Phialina pupula
Diagnosis:
- body fusiform or elliptical, contractile
- length 60–130 µm, width 20–50 µm
- head barrel-shaped, without neck, about 8.5 µm long
- head kineties run counterclockwise
- cytoplasm filled with dumbbell-shaped inclusions
- macronucleus elliptical with adjacent micronucleus
- extrusomes 10 µm long
- 15 longitudinal rows of cilia
- contractile vacuole subterminal
I regularly find Phialina pupula in the mud of Simmelried. Another site is a small pond behind a parking space in the village of St. Ulrich in Austria.
The genus Phialina was revived by Foissner (1983). This genus includes ciliates which have a clearly separated head without a neck. In addition, these species are only slightly contractile. The contractile species with a distinct neck are grouped in the genus Lacrymaria.
In Phialina pupula the head is about 8–10 µm long. In my population it was mostly 10 µm. Spirally kineties run counterclockwise on the head (s. fig. 6). A bundle of parallel extrusomes is arranged in the head, which according to my measurements are about 9 µm long (s. fig. 5).
Phialina pupula is a fast swimming ciliate, which usually appears brown or even opaque black at low magnification. Even at low coverslip pressure, the specimens contract quickly and take on a rather oval shape. As the specimens are always crammed with granules, food vacuoles and inclusions, a closer examination is only possible in squashed specimens. Only then does the ellipsoid macronucleus with an attached micronucleus become visible (s. fig. 7). The most striking feature of Phialina pupula are the numerous dumbbell-shaped inclusions in the cytoplasm (s. figs. 8 and 9). They are highly refractive and light up in the DIC. Nothing is known about their nature and composition. However, they are a characteristic identifying feature of Phialina pupula.
The similar species Phialina macrostomata, Phialina vertens and Phialina vermicularis are all smaller than 85 µm in the elongated state and do not have the characteristic dumbbell-shaped inclusions.
More images and information on Phialina pupula: Jeffrey Silverman-iNaturalist-Phialina pupula
Fig. 1 a-c: Phialina pupula. L = 132 µm. A freely swimming specimen. Obj. 40 X.
Fig. 2 a-c: Phialina pupula. L = 152 µm. A second, freely swimming specimen. Obj. 40 X.
Fig. 3 a-c: Phialina pupula. L = 124 µm. A third, freely swimming specimen. Obj. 40 X.
Fig. 4 a-b: Phialina pupula. L = 120 µm. Two focal planes of a slightly squashed and contracted specimen. Obj. 100 X.
Fig. 5: Phialina pupula. The extrusomes (EX) arranged in the head are about 9 µm long. Obj. 100 X.
Fig. 6: Phialina pupula. Focal plane on the counterclockwise running head kineties (HC). Obj. 100 X.
Fig. 7: Phialina pupula. The macronucleus (Ma) with the adjacent micronucleus (Mi) in a squashed specimen. In the food vacuoles two ingested flagellates (IF) are visible. CV = contractile vacuole. Obj. 100 X.
Fig. 8: Phialina pupula. Focal planes on the dumbbell-shaped inclusions (DI) scattered in the cytoplasm of a slightly squashed specimen. Obj. 100 X.
Fig. 9: Phialina pupula. The dumbbell-shaped inclusiones (DI) in a strongly squashed specimen. The inclusions are about 5 µm long. Obj. 100 X.