Pseudomicrothorax dubius
(Maupas, 1883) Penard, 1922
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Schwemm Moor (Austria)
Phylogenetic tree: Pseudomicrothorax dubius
Diagnosis:
- body ellipsoid, laterally flattened
- length about 100 µm
- oral apparatus subapical
- on left side of mouth opening 3 adoral membranelles
- cyrthopharyngeal basket of about 20 rods
- macronucleus elongated ellipsoidal in mid-body with adjacent micronucleus
- contractile vacuole in mid-body
- an excretion vacuole for digestive residues below contractile vacuole
- extrusomes spindle shaped
- 13–14 longitudinal rows of cilia in deep furrows
- between cilia transversely striated ribs
I have only found a single specimen of Pseudomicrothorax dubius in the Schwemm Moor in Austria. I have not been able to find the species in my other localities. The species seems to be generally rare, as Kahl (1935) only reports two observations by Maupas in Algiers and Penard in Switzerland in his description of Pseudomicrothorax dubius. He obviously did not find the species himself.
Pseudomicrothorax dubius is very similar to the smaller species Pseudomicrothorax agilis, but is about twice as large. In addition, Pseudomicrothorax dubius has 1–2 more longitudinal rows of cilia (13–14), but this is difficult to recognize. Another important identifying feature of Pseudomicrothorax dubius is the elongated macronucleus (s. fig. 4). In Pseudomicrothorax agilis the macronucleus is globular or broadly ellipsoid.
Fig. 1 a-c: Pseudomicrothorax dubius. L = 94 µm. Different focal planes of a slightly squashed specimen from right. Below the contractile vacuole (CV) a second vacuole is located for excretion of digestive residues (DEV). CB = cyrthopharyngeal basket. Obj. 60 X.
Fig. 2: Pseudomicrothorax dubius. L = 94 µm. The right side of the specimen shown in fig. 1 a-c in detail. Near mid-body the excretion porus (EP) of the contractile vacuole is visible. CB = cyrthopharyngeal basket. Obj. 100 X.
Fig. 3: Pseudomicrothorax dubius. L = 94 µm. Focal plane on the surface of the transverse striation of the longitudinal ribs. Obj. 100 X.
Fig. 4: Pseudomicrothorax dubius. The elongated macronucleus (Ma) in a squashed specimen. The cytoplasm is filled with greenish and yellowish food vacuoles of ingested cyanobacteria. EX = spindle-shaped extrusomes. Obj. 100 X.