Kernel density distribution of shell shape angles (ε) against the mean greater shell dimensions (GSD) for 2134 pulmonate genera. The kernel density increases from blue through green and yellow to red colours. Arrow points at the diffuse cluster of approximately 30 roughly equiaxial genera within the approximate ranges of ε = 44°–49° and GSD = 1.5–5 mm and within which P. harli sp. n. (circle) is located.