Shell Morphology and Morphometry of Larval and Post-Larval Donax fossor Say (Bivalvia: Donacidae)

Scanning electron micrograph sequences are presented of the disarticulated shell valves of laboratory-reared larval and post-larval stages of Donax fossor obtained from adult specimens collected in the oceanic surf zone of beaches along the east coast of Assateague Island, VA. These sequences accurately depict the gross morphologies/morphometries and hinge (provinculum) structures of consistently-oriented, disarticulated shell valves of the larvae and/or postlarvae of this species. It is emphasized, however, that a scanning electron microscope is not necessary to observe even fine hinge structures associated with the early ontogenetic stages of the individual specimens depicted in these sequences. Such structures are readily visible using a wide range of optical compound microscopes equipped with high-intensity reflected light sources. The depicted morphologic and morphometric characters provide researchers with invaluable aids for discriminating (using routine optical microscopic techniques) the early life history stages of D. fossor from those of other sympatric species of bivalves isolated from plankton and benthic samples.