Morphological and Genetic Features of Culmenella prashadi (Heterobranchia: Planorbidae) Newly Discovered in Fukushima Prefecture, Japan

Abstract

Culmenella prashadi (Clench, 1931) is a critically endangered freshwater snail whose habitats have significantly declined despite its wide recorded distribution. The authors discovered a new population of Cu. prashadi in a small mountain pond in Fukushima Prefecture, northern Honshu, Japan, from where the species had not been previously recorded. Morphological examination of the shell, head-foot, and digestive, reproductive, and central nervous systems revealed that the examined population had similar features to previously dissected snails from Ishikawa Prefecture, while exhibiting intraspecific variations in the accessory preputial organs and radulae. The present anatomical observations confirmed that Cu. prashadi can be distinguished from its congeners and the closely related Camptoceras hirasei Walker, 1919 based on morphological differences in the mantle flap, male reproductive organs, and central nervous system. Base substitutions were also identified between the haplotypes of the populations in Fukushima and Aomori Prefectures.