Evolutionary retention of defensive lateral pedal glands in the smallest siphonariid limpet (Gastropoda: Pulmonata)

Abstract

Despite its cryptic habitat and habits, light and transmission electron microscopy has revealed that like many other siphonariids Siphonaria compressa, the smallest species of this genus, possesses lateral pedal glands. The pear-shaped glands (about 120 µm long×70 µm maximum diameter) open via a pore, and are multicellular with three types of secretory cell that surround a central lumen. The glands of this minute pulmonate limpet are similar in structure to its larger relatives, suggesting that they are defensive in function.