cells obovate or lemon-shaped, apically obliquely truncated
ventral side with short apical incision
length about 15 µm, width about 7.5 µm
ingestion apparatus a conical tube, reach mid-body
two flagella of unequal length
nucleus mid-body, shiftet laterally
contractile vacuole anterior third
pellicle with a wide, longitudial striation
Ploeotia pusilla
So far I have only found Ploeotia pusilla in the Simmelried. In fresh samples, Ploeotia pusilla is hard to recognize due to its small size, but the species likes to settle on the floating coverslip and is then easy to observe.
The species Entosiphon obliquus (syn. Entosiphon obliquum) was transferred to the genus Ploeotia as Ploeotia obliqua by Schroeckh et al. in 2003. It was then renamed to Ploeotia pusilla by Kubín & Jurán in 2024.
The genus Ploeotia differs from the genus Entosiphon in the ultrastructural structure of the tube-shaped ingestion apparatus and the structure of the pellicle. Under the light microscope, only the structure of the pellicle can be recognized, which in Ploeotia pusilla consists of a wide longitudinal striation (s. figs. 1 c and 4 c).
Fig. 1 a-c:Ploeotia pusilla. L = 12.5 µm. A freely swimming specimen from ventral (a) and dorsal (b, c). Note the wide striation of the pellicle (SP). F1, F2 = flagella, CV = contractile vacuole, IA = tube shaped ingestion apparatus, Nu = nucleus. Obj. 100 X.
Fig. 2 a-b:Ploeotia pusilla. L = 12.5 µm. The slightly squashed specimen as shown in fig. 1 a-c. CV = contractile vacuole, IA = tube shaped ingestion apparatus, Nu = nucleus. Obj. 100 X.
Fig. 3 a-c:Ploeotia pusilla. L = 13 µm. A second freely swimming specimen. Not the short, ventral incision (arrow). F1, F2 = flagella, CV = contractile vacuole, IA = tube shaped ingestion apparatus. Obj. 100 X.
Fig. 4 a-c:Ploeotia pusilla. L = 13 µm. A third, freely swimming specimen from ventral. CV = contractile vacuole, IA = tube shaped ingestion apparatus, Nu = nucleus, SP = striation of the pellicle. Obj. 100 X.