MEPS 119:191-197 (1995)  -  doi:10.3354/meps119191

On the intertidal rocky shores of central Chile, the lichen Thelidium litorale (Ascomycete: Verrucariacea) is commonly found encrusting shells of gastropods such as Scurria araucana, S. ceciliana and S. boehmita, and plates of the intertidal barnacles Jehlius cirratus and Chthamalus scabrosus. This study focuses on the relationship between T. litorale and shells of the limpet S. boehmita. In the field, this host shows the highest percentage of lichen prevalence among several intertidal species. Although T. litorale is able to penetrate the limpet shell layers lying above the myostracum (m), the observed penetration levels appear related to the width of the shell layers. Among the 3 species of limpets, S. boehmita exhibits the thinnest m+2 layer and this could facilitate lichen penetration. As a result of the association, the limpet develops an external shell pattern remarkably resembling the shape of the aperture of the intertidal barnacles J. cirratus and C. scabrosus. This lichen-mediated mimicry can be explained by lichen-induced erosion, which leads to the disclosure of the internal and otherwise unexposed shell design of S. boehmita. The possible role of T. litorale as a biological modifier of external limpet shell pattern is discussed.

Central Chile . Intertidal lichen . Limpets . Mimicry