Campeloma Rafinesque, 1819

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

Campeloma Rafinesque, 1819

Examined species: Campeloma decisum (Say, 1817)

( Figs 2B , 3B , 6B ).

Remarks: The elongated, inverted-comma-shaped and concentric operculum is the most important combination of diagnostic opercular characters for Campeloma . The apex–nucleus distance is clearly longer than the base–nucleus distance. This character is seen only in Campeloma and Lioplax , the two extant genera of Lioplacinae .

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.