On the inner morphology of pomatiid opercula - hidden structures (Gastropoda: Pomatiidae)
Wilmsmeier, Lisa; Neubert, Eike
The Pomatiidae are terrestrial operculate land snails with semi-calcified opercula. Whether these contain useful information as indicators of phylogenetic relationships within the group has been subject to debates. This study describes the morphology of opercula of different species of Pomatiidae and some Annulariidae, mainly focusing on the recently observed pores that can be seen on the periphery of the operculum. These pores are found to form the opening of simple small canals that are formed during the growth of the operculum. These microcanals were found in all examined species except in the genera Tudorella and Leonia, which instead have lamellae on the opercular surface. These are here considered to be homologous to the microcanals. The form of the microcanals and the particular formation of the operculum seem to be consistent within a given genus, add stable characters for genus definition and thus might be a useful character for future phylogenetic analysis.