I find Trichospira inversa in some of my sampling sites, but only rarely and irregularly. The species is found exclusively in the uppermost layer of the mud. What all sites have in common is that there is a deposit of fallen leaves. In general, the species seems to occur only rarely and there are only descriptions by the first describers, Penard (1922) and Kahl (1926).

Trichospira inversa has an unusual structure, which only becomes apparent under high magnification. The mouth opening (the vestibulum) is located subapically. A spiral band of cilia originates from there and runs clockwise to the posterior end. There, however, it merges into a transverse ring. Kahl already recognized that these spirall band is consisting of two parallel rows of cilia, separated by less than 1 µm (s. fig. 5).

Very large food vacuoles are often found in the cytoplasm (s. fig. 4). A large, also oval micronucleus is attached to the oval macronucleus (s. fig. 6). The contractile vacuole is clearly subterminal (s. fig. 3 b).

Under the pellicle there is a dense fringe of extrusomes (s. fig. 7 a), which are very thin and, according to my measurements, are quite consistently 4.5 µm long (s. fig. 8). In squashed specimens only a few extrusomes are found, as they are quickly ejected.