COMPARATIVE STUDIES ON MORPHOLOGY OF THE GLOCHIDIA OF SIX MUSSEL SPECIES(MOLLUSCA:UNIONIDAE)

The marsupia and glochidia of Six freshwater mussel species,Anodonta woodianawoodiana,Cristaria plicata, Lanceolaria gladiola, Unio douglasiae, Lamprotula scripta and L. caveata were studied morphologically.The marsupia onhese specics of mussels are allexobranchial,and further the marsupia of the former four species are homogenial andthe latter two tetragenial.The size of the glochidia varies considerably in relation to theirspecies identity.Furthermore,glochidia of all the former four species are hooked on theirshells,but may be distinguished from each other by the morphology of their shell hooks.However,glochidia of the latter two species are unhooked,with structures similar to thefunctions of the shell hooks.For L. scripta,a spine was observed in the middle of theventral margin of each shell,whilst for L. caveata,a suctorial structure observed in clozeto the ventral margin of the shells.It was therefore indicated that types of marsupia andglochidia,and mopohology of glochidial shell hooks can be used together as diagnosticcharacters in the classification of bivalves.