The winged mapleleaf (Quadrula fragosa (Conrad, 1835)) historically occurred in rivers across eleven U.S. states but now only occurs in a small portion of a few rivers. The glochidial host(s) for this federally endangered species are unknown which makes it nearly impossible to determine the viability of imperiled mussel populations either in degraded habitats, where they now occur, or in habitats being considered for translocation of mussels. We studied brooding winged mapleleaf in the St. Croix River and the Wet Laboratory, University of Minnesota. Suitable glochidial hosts were determined using a standard artificial infestation protocol. During the brooding period a swollen excurrent aperture was observed among brooding and some non-brooding individuals. Glochidia were released as individuals or in conglutinates. None of the 48 trials conducted on 28 fish species facilitated glochidia metamorphosis, although two juvenile winged mapleleaf excysted from a channel catfish during a concurrent study for the Wisconsin Department of Natural Resources. Unfortunately several catfish succumbed to 'Ich' prior to the end of the study and may have compromised our ability to identify additional suitable hosts. Juvenile mussels were collected from St. Croix River fishes naturally infested with glochidia but none of the recovered mussels were winged mapleleaf. Additional work is needed to determine the function of the swollen excurrent aperture displayed during the brooding season and to verify that catfishes serve as glochidial hosts under artificial and natural conditions.
 
 

Swollen excurrent aperture of winged mapleleaf during brooding period.	Winged mapleleaf mussel releasing conglutinates in laboratory.
Conglutinates released by winged mapleleaf.	Winged mapleleaf glochidia.
Winged mapleleaf glochidium.	Winged mapleleaf glochidium micropoints.
Premetamorphosed winged mapleleaf juvenile.	(Click on thumbnail for more detailed picture.)

Last modified on July 29, 2000