Permanent slides for morphological studies of small crustaceans: Serban's method and its variation applied on Bathynellacea (Malacostraca)

Morphological studies of small invertebrates often involve the preparation of slides to observe minute body parts under a compound microscope. Preparation should facilitate observation, through traditional optical microscopy, of small surface structures on different planes, like pores, spines and setae. Various methods and techniques, using different mounting media that specialists have adopted to observe and preserve small crustaceans, have their advantages and disadvantages. Within the order Bathynellacea, specimens in the family Bathynellidae are particularly challenging due to their small size (0.5 to 2.25 mm body length) and very delicate exoskeleton, which tends to be completely digested when using common clearing mounting media, making future consultations impossible. Permanent slides are fundamental to preserve small specimens for scientific collections, because temporary slide preparations can easily result in the loss of body parts in the passage between slide and vial and vice versa. Dr Eugene Serban worked on Bathynellacea for more than 40 years, improving the preparation and preservation of delicate specimens using a stained glycerol-jelly and double cover slip mounting technique. His method is described here with a variation that speeds up the original procedure and was implemented in most recent years by one of the authors (A.I.C.). The technique provides excellent preservation and visualization of body parts on permanent slides, which do not need curation tasks and can last for many years.