Taia Annandale, 1918

Zhang, Le-Jia & von Rintelen, Thomas, 2021, The neglected operculum: a revision of the opercular characters in river snails (Caenogastropoda: Viviparidae), Journal of Molluscan Studies 87 (2), pp. 1-14 : 12

Taia Annandale, 1918

Examined species: Taia naticoides (Kobelt, 1909) ( Figs 4Q , 5Q , 7Q ); Taia shanensis (Kobelt, 1909) ( Figs 4R , 5R , 7R ).

Remarks: Taia can be distinguished from other genera with a concentric inverted-comma-shaped operculum by the following combination of characters: a subcentral nucleus that is very close to the inner margin; a large nuclear region with many fine, dense grains or veins; an inner opercular region completely or partly covered by a rough sandpaper-like layer; an enamel region that is thickened and deeper in colour near the inner opercular region; and a thin, wide marginal region that obviously differs in colour from the enamel region.

The inner nuclear region of T. shanensis is almost completely covered by a thick sandpaper-like layer, which is mostly absent in T. naticoides .

Figures

Figure 4. Interior surface of opercula of the viviparid species studied. A. Celetaia persculpta. B. Ussuripaludina ussuriensis. C. Sinotaia angularis. D. Anularya mansuyi. E. Anularya bicostata. F. Torotaia mainitensis. G. Neothauma tanganyicense. H. Bellamya phthinotropis. I. Bellamya trochlearis. J. Idiopoma umbilicata. K. Idiopoma dissimilis. L. Filopaludina luzonica. M. Filopaludina martensi. N. Filopaludina bengalensis. O. Filopaludina gigantea. P. Trochotaia trochoides. ƍ. Taia naticoides. R. Taia shanensis. S. Notopala ampullaroides. T. Angulyagra cf. polyzonata. Scale bar: 5 mm.

Figure 5. Exterior surface of opercula of the viviparid species studied. A. Celetaia persculpta. B. Ussuripaludina ussuriensis. C. Sinotaia angularis. D. Anularya mansuyi. E. Anularya bicostata. F. Torotaia mainitensis. G. Neothauma tanganyicense. H. Bellamya phthinotropis. I. Bellamya trochlearis. J. Idiopoma umbilicata. K. Idiopoma dissimilis. L. Filopaludina luzonica. M. Filopaludina martensi. N. Filopaludina bengalensis. O. Filopaludina gigantea. P. Trochotaia trochoides. ƍ. Taia naticoides. R. Taia shanensis. S. Notopala ampullaroides. T. Angulyagra cf. polyzonata. Scale bar: 5 mm.

Figure 7. Shells of the viviparid species studied. A. Celetaia persculpta. B. Ussuripaludina ussuriensis. C. Sinotaia angularis. D. Anularya mansuyi. E. Anularya bicostata. F. Torotaia mainitensis. G. Neothauma tanganyicense. H. Bellamya phthinotropis. I. Bellamya trochlearis. J. Idiopoma umbilicata. K. Idiopoma dissimilis. L. Filopaludina luzonica. M. Filopaludina martensi. N. Filopaludina bengalensis. O. Filopaludina gigantea. P. Trochotaia trochoides. ƍ. Taia naticoides. R. Taia shanensis. S. Notopala ampullaroides. T. Angulyagra cf. polyzonata. Scale bar: 10 mm.