3-DIMENSIONAL FLUORESCENCE IMAGEING OF THE BUCCAL APPARATUS AND CLAWS FOR SPECIES IDENTIFICATION IN EUTARDIGRADES

Studies of eutardigrades at the specific level face several problems because species are differentiated by few characteristics, which are sometimes difficult to observe. The buccal apparatus with placoids are among the most important characters for species identification. Placoids alternate in position with three equal cuticular apophysis, which are posterior to the end of the buccal tube. The larger anterior placoids, called macroplacoids, are present in either two or three transvers rows. Smaller, posterior placoids are termed microplacoids. Furthermore, size, shape and number of claws are additional important characters which have commonly been used in tardigrade systematics. The buccal apparatus and claws show (after excitation with blue or green light) sufficient auto-fluorescence to be detected at a range of wavelengths (green to red). New techniques for optical sectioning and 3-dimensional reconstruction with increased positional accuracy and spatial resolution allow the reproduction of the real 3D structure of the buccal apparatus. Thus, modern epi-fluorescence techniques provide easy and fast access to important taxonomic features of tardigrades and at the same time produce demonstrative visualizations. We investigated several eutardigrade species with this new methods and displayed the 3- dimensional buccal apparatus and claws for species determination and description. As an outlook: the 3-dimensional image data can be used for the production of spatial models.