Giardia Ancey, 1907, was proposed as a generic name for Indochinese tree snails with sinistral, transparent and elongated ovate to conic shells, which comprised Bulimus siamensis Redfield, 1853, and Bulimus rhombostomus Pfeiffer, 1861. Unfortunately, this generic name was preoccupied by protozoan parasite Giardia Künstler, 1882. There are no junior synonyms available for Giardia Ancey, 1907, so we propose a replacement generic name Anceyoconcha, and therefore new combinations, Anceyoconcha siamensis (Redfield, 1853) and Anceyoconcha rhombostoma (Pfeiffer, 1861), for the two species currently assigned to the genus. External morphology of shell, living body, radula, and genital system of both species are described and compared to other related genera, and the distinctiveness of Anceyoconcha is confirmed. [ABSTRACT FROM AUTHOR]