Morphological description of the glochidia of Buldowskia suifunica (Bivalvia: Unionidae): External and internal structures and organ systems

Abstract

Abstract Freshwater mussels of the genus Buldowskia (Bivalvia, Unionidae) are distributed from the Amur River basin in Russia and China southward to the Korean Peninsula and some Japanese islands. This work is an integrative morphological study of Buldowskia suifunica glochidia from locations in the Primorsky Territory, the Russian Far East. Here, we first detected that glochidia taken from the same gill have asynchronous development. We characterized the external and internal morphology of the shell. Here, we described the morphology of sensory system that consists of hair cells as well as nonhair cells with in three stages of larval development (immature, intermediate and mature glochidia). We detected muscle system is composed of massive adductor and minor muscle bundles. The FMRFamidergic nervous system turned out to be a complex system includes basalcells (neurons), their neurites and anterior neurons. FMRFamide and tubulin was found in all neurons. For the 5-HT nervous system, we detected only four 5-HT-lir neurons in glochidia. We concluded that B. suifunica glochidial nervous system differ drastically from those of the larval comparable systems of marine and freshwater mollusks. However, the general outline of the structure of the sensory, muscular and nervous systems is still preserved within the taxon bivalves.