Paper No. 9
Presentation Time: 8:00 AM-12:00 PM
ROLE OF AGE, GENDER, AND SAMPLE LOCATION ON THE CUTICULAR MICROSTRUCTURE OF A RECENT POPULATION OF CALLINECTES SAPIDUS AND ITS IMPLICATIONS FOR THE STUDY OF FOSSIL CUTICLE
Examination of decapod crustacean cuticular microstructure may aid in both systematic classification and expand the number of characters available for the development of phylogenies. Previous work has led to the development of the Analytical Cuticle Classification Scheme (Waugh, 2002), which is used to discriminate structures and geometries in the decapod cuticle. This classification has no implicit phylogenetic significance but lays the groundwork for recording the diversity of data that can be observed in decapod cuticle. The purpose of this study was to explore the extent to which age, gender, and the area on the crab that is sampled affect the characters recorded in the classification scheme. With an understanding of the effect of age, gender, and sample location, an efficient sampling strategy can be developed that can be applied to the large number of species that will be sampled as part of the next phase of our study. To test the effect of age, gender, and location on crabs, a small population of the blue crab Callinectes sapidus was purchased "live frozen" from a commercial fisherman and sampled at various locations on the carapace and chelipeds. Samples were then dried in alcohol, embedded in epoxy, and thin sectioned. Both qualitative parts of our classification (extent of calcification, tubercle construction and others), as well as newly devised morphometric measurements (number of laminations, layer thicknesses, and cuticular prism dimensions) were applied. These were compared across our sample population of Callinectes sapidus to determine the extent to which the variables will affect data to be used in systematic and phylogenetic analyses. Data from C. sapidus were also compared with other taxa to illustrate intraspecies and interspecies variation. Fossil cuticle that can be destructively sampled is not always easy to obtain. When it is available, researchers do not always have the luxury of choosing the best sample location, so this work will also help determine the extent to which data obtained from non-standard sample locations can be integrated into the dataset.