Lioplax Troschel, 1857

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 : 5

Lioplax Troschel, 1857

Examined species: Lioplax subcarinata (Say, 1817) ( Figs 2A , 3A , 6A ).

Remarks: Lioplax is the only genus in the family with a paucispiral operculum at early developmental stages, which is different from the concentric operculum of all other genera of Viviparidae . In addition, the semi-elliptical shape and lower central location of the nucleus are also diagnostic opercular characters for this genus.

Figures

Figure 2. Exterior surface of opercula of the viviparid species studied. A. Lioplax subcarinata. B. Campeloma decisum. C, D. Callinina georgiana. E. Callinina intertexta. F. Tulotoma magnifica. G. Riƌularia auriculata. H. Amuropaludina praerosa. I. Viƌiparus ƌiƌiparus. J, K. Viƌiparus contectus. L. Mekongia jullieni. M. Tchangmargarya multilabiata. N. Tchangmargarya yangtsunghaiensis. O. Cipangopaludina nagaensis. P. Cipangopaludina crassibuca. ƍ. Cipangopaludina chinensis. R. Margarya melanioides. S. Heterogen longispira. T. Heterogen japonica. Scale bar: 5 mm.

Figure 3. Interior surface of opercula of the viviparid species studied. A. Lioplax subcarinata. B. Campeloma decisum. C, D. Callinina georgiana. E. Callinina intertexta. F. Tulotoma magnifica. G. Riƌularia auriculata. H. Amuropaludina praerosa. I. Viƌiparus ƌiƌiparus. J, K. Viƌiparus contectus. L. Mekongia jullieni. M. Tchangmargarya multilabiata. N. Tchangmargarya yangtsunghaiensis. O. Cipangopaludina nagaensis. P. Cipangopaludina crassibuca. ƍ. Cipangopaludina chinensis. R. Margarya melanioides. S. Heterogen longispira. T. Heterogen japonica. Scale bar: 5 mm.

Figure 6. Shells of the viviparid species studied. A. Lioplax subcarinata. B. Campeloma decisum. C, D. Callinina georgiana. E. Callinina intertexta. F. Tulotoma magnifica. G. Riƌularia auriculata. H. Amuropaludina praerosa. I. Viƌiparus ƌiƌiparus. J, K. Viƌiparus contectus. L. Mekongia jullieni. M. Tchangmargarya yangtsunghaiensis. N. Tchangmargarya multilabiata. O. Cipangopaludina nagaensis. P. Cipangopaludina crassibuca. ƍ. Cipangopaludina chinensis. R. Margarya melanioides. S. Heterogen longispira. T. Heterogen japonica. Scale bar:10 mm.