Trochotaia Brandt, 1974 Examined species: Trochotaia trochoides (Martens, 1860) (Figs 4P, 5P, 7P). Remarks: Trochotaia can be distinguished from the other genera by a concentric inverted-comma-shaped operculum that exhibits the following combination of characters: a thick, rough layer with many grains or veins over the whole of the inner opercular region; a clearly convex outer margin; and a smooth enamel region with a dense ray-like pattern.

Published as part of Zhang, Le-Jia & von Rintelen, Thomas, 2021, The neglected operculum: a revision of the opercular characters in river snails (Caenogastropoda: Viviparidae), pp. 1-14 in Journal of Molluscan Studies (eyab 008) (eyab 008) 87 (2) on page 13, DOI: 10.1093/mollus/eyab008, http://zenodo.org/record/15098489