Pyxicola operculigera Kent, 1882
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Harbor basin of Kloster (Hiddensee)
Phylogenetic tree: Pyxicola operculigera
Diagnosis:
- body trumpet-shaped
- length 60 µm (of zooid)
- lorica vase-shaped, chitinioid, often wavy margin
- lorica colorless and transparent, brownish-orange in older specimens
- operculum circular
- zooid protrudes about 1/3 out of lorica
- stalk long, about twice of body length, colorless
- one contractile vacuole in anderior half
- pellicle with transverse striation
- macronucleus vermiform
Pyxicola operculigera is a marine species which I found in large numbers in the harbor basin of the village of Kloster on the island Hiddensse.
The description of Pyxicola operculigera by Kahl is very brief. The main features are the vase-shaped body with a neck-like constriction and a very long stalk, which can reach about twice the length of the body (s. fig. 1 a-b). Kahl also mentions the wavy margin of the lorica, which I was able to observe in practically all specimens. Pyxicola operculigera has a so-called operculum, which is attached to the persistome and serves to seal the lorica aperture when the zooid retracts (s. figs. 3 and 4 c).
At 60–85 µm, the specimens in my population were somewhat larger than Kahl states (60 µm). Extended specimens are difficult to examine because they immediately retract when pressure is applied by the coverslip. However, I was able to clearly identify the position of the contractile vacuole, the transverse striation of the pellicle and parts of the macronucleus (s. fig. 4 a-c).
More images and information on Pyxicola operculigera: Wolfgang Bettighofer-Protisten.de-Pyxicola operculigera
Fig. 1 a-b: Pyxicola operculigera. L = 83 µm (of zooid). An extended older specimen with a brownish-orange lorica and a long stalk (L = 152 µm). Obj. 40 X.
Fig. 2 a-b: Pyxicola operculigera. L = 72 µm (of zooid). A second, younger specimen in an almost colorless lorica. Obj. 40 X.
Fig. 3: Pyxicola operculigera. The circular operculum (OP) of an extendes specimen with a diameter of 20 µm. Obj. 40 X.
Fig. 4 a-c: Pyxicola operculigera. L = 67 µm (of zooid). Different focal planes of an extendes (a) and fully retracted (c) specimen. Note the closed aperture of the lorica with the operculum (Op) in the retracted specimen. CV = contractile vacuole, IB = infundibulum, Ma = macronucleus, SP = transverse striation of the pellicle. Obj. 100 X.