Colour pattern of Naticopsis planispira (Neritimorpha, Gastropoda) shell from Upper Carboniferous of Upper Silesian Coal Basin, southern Poland

Abstract

A zigzag colour pattern with additional collabral belts and irregular spots was observed on a shell of Naticopsis (N.) planispira (Phillips, 1836) found in the Gołonóg Sandstone marine faunal horizon (Namurian A, the Upper Silesian Coal Basin, Poland). A disruption in the colour pattern was also observed to have occurred during ontogenetic shell growth. In this specimen, it appeared in the healed shell damage on the outer lip. So far, only nine Carboniferous species of Naticopsis have been reported with the colour pattern preserved. The most common are the zigzag-type and the spiral band-type. Individual taxa clearly differ in the morphology of the chevrons (direction and angles of breaks) and the location and width of the spiral bands on a whorl. However, the color patterns may not be diagnostic features for the Naticopsis species, because of the large intraspecific variation and colour pattern polymorphism on the neritimorph shells. Colour patterns on Palaeozoic neritimorph shells most likely served as camouflage with respect to the bottom surface in the photic zone.