Histiona aroides (Pascher, 1943)
Most likely ID: n.a.
Synonym: n. a.
Sampling location: Simmelried
Phylogenetic tree: Histiona aroides
Diagnosis:
- cell in hyaline lorica
- length 13–22 µm
- lorica is campanulate shaped, with a bulbous extension on level of the cell
- cell with two flagella with different length
- cell with a sail-shaped cytoplasm lip
- short flagellum is moving or attached to the cytoplasm lip
- spherical nucleus with central nucleolus in posterior third
- contractile vacuole at the base of the cytoplasm lip
So far I could detect Histiona aroides only once in July 2021 in the Simmelried. I found colonies of 10 – 20 specimens each on algae filaments. The lorica of Histiona aroides has a campanulate shape, with a bulbous extension at the level of the cell. The flagellate in the lorica forms a sail-shaped cytoplasm lip. Two flagella of different length arise from the base of this cytoplasm lip. The long flagellum swirls food (bacteria) in a whip-like manner. The function of the cytoplasm lip seems to be either a funnel function or the swirled bacteria stick to it and are then stripped off by the second, short flagellum. The short flagellum is difficult to see. It is supposed to be adjacent to the plasma lip. However, I could observe that it also seems to move over the plasma lip (s. fig. 3a-c).
Fig. 1: Histiona aroides. L = 15 -18 µm (from stalk of lorica to top of cytoplasm lip). A colony on a alga filament. Obj. 100 X.
Fig. 2 a-d: Histiona aroides. L = 17 µm (from stalk of lorica to top of cytoplasm lip). Different focal planes of a specimen. CL = sail-shaped cytoplam lip, CV = contractile vacuole, LF = long flagellum, LO = lorica, Nu = nucleus with central nucleolus. Obj. 100 X.
Fig. 3 a-c: Histiona aroides. L = 15 µm (from stalk of lorica to top of cytoplasm lip). The short flagellum (arrow) is attached to the cytoplasm lip or it moves over the lip. Obj. 100 X.