Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 98. (Budapest 2006)

Makranczy, Gy.: Systematics and phylogenetic relationships of the genera in the Carpelimus group (Coleoptera: Staphylinidae: Oxytelinae)

men, placed on top of a microscope slide, such preparation could be studied under a compound microscope up to 400 times magnification, occasionally higher, and provided clear, sharp images. This is mainly due to the superior optical properties of the Euparal. The method described below gives a good compromise between satisfying the needs of individual, detailed investigation and serial identification work. Genital preparation method for plastic microslides attached to the pins of the specimens. The key object of this preparation method is a cavity slide covered with a normal microscopic slide (Fig. 9). This provides easy-to-access area with little airspace; this latter feature is important, because little solvent tends to evaporate very fast, lots of solvent makes it difficult to find/manipulate the object. The appropriate cavity slide (deep cavity, double, 3mm thickness) avoids the very inconvenient situation of the alcohol running in between the glasses of the cavity slide and the one covering it. This is never a problem with the potassium hydroxide solution or the distilled water, but it is with the absolute (100%) ethyl alcohol because of its different surface tension. 1. Dissect in distilled water (on the card, a separate wet cardboard or tissue paper or as you like). For some kinds of staphylinid beetles, especially the very small ones, it is advantageous to detach the tip of abdomen (eighth segments and thereafter) and keep this unit together (Fig. 10) until it is placed into the Euparal drop and only further dissect it within the drop. 2. Place the object into a drop of cold, concentrated potassium hydroxide solution in the cavity of the slide. It should be left there for about 5 hours at room temperature, depending on the sclerotization and pigmentation. Heating and even boiling is suggested by other authors (e.g. HANLEY & ASHE 2003), but this may destroy delicate structures and was not used by me. 3. Remove the object and place it into a drop of distilled water; neutralization of the potassium hydroxide can be facilitated by adding a very little acetic acid to the distilled water (it should not be more concentrated than 2-4% acid, otherwise it causes shrinking and distortion of the structures). This drop should be in another cavity slide; a difficulty is that the object may dry out while moved from one drop of solution to another. This can be avoided by moving it either with a sharpened wooden stick or with a tiny piece of paper tissue held by a forceps (Fig. 9). Both absorb enough fluid to keep the object wet while being moved, yet not enough to corrupt the fluid in the next step. The washing can last from a few minutes to days but care must be taken to avoid accidental drying with longer washing times. 4. Next step is an alcohol dehydration series: first 20% then 80%, finally 100% ethyl alcohol. The concentrations arc approximate, with the exception of the last. When the object is moved through all these solutions, staying for about 20 minutes in each, it is ready to be moved from the 100% ethyl alcohol into a droplet of Euparal on the plastic slide (see 5 below). The alcohol evaporates very rapidly, leaving air bubbles in the structures, so the last step has to be done with the greatest care and speed. For very delicate objects, an intermediate step, immersion in Euparal Essence before the transfer to Euparal, may be advisable to avoid shrinking or distortion. 5. Finally, prepare a suitable plastic slide (suggested dimensions: 6x19 mm) with a little drop of Euparal on it. The droplet should be just large enough to fully cover the object when it is placed into it. Then the object is moved into the Euparal drop. When the object settles (1 minute), dissection must be done within the drop and the parts arranged in the order and orientation preferred for study. The first little drop will dry within a few minutes, because its dilution by the alcohol contained in the structures themselves. The reason of transferring the objects to such a small amount of medium is to quickly fix the objects on the slide, so that the dissected parts will not float around and become fixed in undesirable positions. After about 10 to 20 minutes, another small drop should be added on top. Some experimentation is needed with the necessary time and the amount of Euparal, since it may differ with size, and certain other characteristics specific to the taxon studied. The preparation must not left to dry completely in the first small drop stage (dangers: air bubbles, distortion). Gradually in-