A contribution to the knowledge of a Chinese endemic genus Stilpnodiscus Mollendorff, 1899 (Gastropoda: Pulmonata: Bradybaenidae), with a description of two new species

Three species of a Chinese endemic genus Stilpnodiscus Möllendorff, two of them (S. moellendorffi and S. yeni) new, are conchologically and anatomically examined, based on material from Gansu and Sichuan Provinces, W China. Their genitalia are described in detail; a finger-shaped structure of unknown function, found in S. moellendorffi sp. n., is unique among bradybaenids. Definition of the genus is discussed. Principal component analysis of seven metric characters and two coefficients reveals a compatibility of conchological features between the two new species. Their conchological resemblance, combined with the great dissimilarity of the dart sac and sympatric distribution, suggests a particular speciation process.