Shell Color Diversity and Sexual Dimorphism in Land Snail Cyclophorus ateribalteiformis (Caenogastropoda: Cyclophoroidea): A Preliminary Observation

Cyclophorus ateribalteiformis is a dioecious land snail species endemic to China. In a recent field survey in Xishuangbanna, Yunnan Province, we observed shell color dimorphism in this species, with a pale-yellow shell morph found only in males. Measurements of 11 specimens showed that females have significantly greater shell height than males, indicating sexual dimorphism in shell size. DNA sequences of the cox1 and 16S rRNA genes confirmed that all individuals belong to the same species. Although sexual dimorphism in shell size and color has been reported in a few terrestrial caenogastropods, it is rare in Cyclophoroidea. Our study provides preliminary evidence of male-specific shell coloration and size dimorphism in C. ateribalteiformis. Further sampling and research are needed to confirm and better understand this phenomenon.