Bellamya Jousseaume, 1886

Examined species: Bellamya phthinotropis (Martens, 1892)

(Figs 4H, 5H, 7H);

B. trochlearis Martens, 1892 (Figs 4I, 5I, 7I).

Remarks: Bellamya can be distinguished from other genera with a concentric inverted-comma-shaped operculum by the following combination of characters: opercular height almost as same as width; a small, smooth shiny nuclear region; and a thin and narrow marginal region.

The operculum of B. trochlearis differs from that of the other species examined, B. phthinotropis, by having a more notably convex outer margin—this fits the shape of the aperture and has a strong keel.