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Chelonethida (Pseudoscorpionida)
Material Preparation

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TEMPORARY SLIDE PREPARATION IN PSEUDOSCORPION TAXONOMY

It is often not desirable to prepare permanent slide mounts of pseudoscorpions, either due to the fragility of the material, or because the custodian of the specimens refuse to allow such mounts. The following technique has been devised to allow for the manipulation of the dissected parts, hopefully minimizing the risk of losing the pieces, but allowing for detailed microscopic examination of the specimen.

1. Remove the relevant structures from the body of the specimen with a minuten pin or similar instrument. Standard pieces to be dissected are a chela, a pedipalp, a chelicera, and one leg I and one leg IV.
2. Transfer structures from 75% ethanol to a microscope slide upon which a drop or two of lactic acid has been placed. Smaller structures should be placed in 50% lactic acid, whereas larger, more robust structures can be safely immersed in 100% lactic acid. The coverslip must be supported by something to stop any crushing of the dissected pieces. I have used small pieces of nylon fishing line (which can be purchased in may different sizes to suit the diameter of the structure, but beware, as the nylon slowly dissolves in the lactic acid, and cannot be used for extended periods). Small fragments of cover slip or glass beads may be preferable.
3. The body can also be cleared in lactic acid. The clearing process can be quickened by making an incision in the pleural membrane-this is particularly important for larger specimens. The body can be observed in a well-slide, or by propping the coverslip as described above.
4. The structures slowly clear in the lactic acid, and can be safely left in the mount for many weeks.
5. One drawback to this technique is the clearing of the genitalia, as these preparations are never as good as traditional slide-mounted material. However, for large specimens such as chernetids, I have dissected the genitalic sternites and the associated genitalia (both male and female) from the specimen with a minuten pin and mounted them in lactic acid (or glycerol) for detailed examination.
6. A problem with this entire technique is that small parts are easily lost, especially if handled by non- specialists. I carefully transfer the dissected pieces into a "Glass Genitalia Vial" (12 mm X 4 mm, available from BioQuip Products, 17803 LaSalle Ave, Gardena, CA 90248, USA) and use a tight piece of cotton wool as a plug. The body is placed in a separate micro vial, and both vials are placed in a larger vial for storage in ethanol.

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PREPARATION OF PSEUDOSCORPIONS FOR MICROSCOPIC STUDY

Preserve and store in 75-80 % ethyl alcohol with about 1-2 % glycerine.
For dissection, transfer to deep depression slide or small syracuse dish containing 95 % alcohol. Under dissecting microscope and using tow pairs of fine (#5) watchmakers tweezers remove both palps, one leg I, one leg IV, and both chelicerae. Pierce the abdomen through the pleural membrane on the side from which the legs were removed.
Transfer body to another deep depression slide or small dish containing 10 % KOH. Cover and let stand several hours or overnight.
Remove alcohol from appendages by means of a fine pipet and add 100 % alcohol. Cover and let stand for about one hour. Then remove alcohol, add clove oil, cover and let stand.
When body is softened, press out with forceps or needle the contents of abdomen and cephalothorax through the opening made previously. Transfer body to another depression slide or dish containing distilled water with a small amount of wetting agent (e.g. Kodak Photoflo), and by alternately pressing and releasing the abdomen, pump out all the loose contents. When the body is clean, remove the water and add a solution of N/50 HCl in 30 % alcohol. Cover and let stand for about an hour. Then rinse briefly with 95 % alcohol and add 100 % alcohol. Cover and let stand for about an hour. Remove the alcohol and add clove oil. After the alcohol is washed out, the body may be placed in the depression slide or dish with the appendages.
The body and appendages should remain in clove oil (several changes) until completely cleared, which may take several days for large, heavy specimens.
For permanent mounting, the parts of the specimen are transferred to a microscope slide taking care to carry over a minimum amount of clove oil. The body and the two palps are placed at one side of the slide together with tow short lengths of glass rod of sufficient diameter to hold a cover glass above the specimen. A large drop of Canada Balsam (or other permanent mounting medium) is added and the parts are arranged in an orderly fashion -- the body is oriented with the ventral side up; one entire palp is oriented with the dorsal side up; the chela is removed from the other palp, the movable finger opened wide, and the organ oriented with the lateral side up. The two legs and both chelicerae are placed nearby on the same slide and covered with a smaller drop of mounting medium -- the legs are oriented with the anterior sides up; one chelicera is oriented with the dorsal or ventral side up; and the other chelicera is oriented with the lateral side up. The cover glass over these appendages should also be supported by bits of glass rod to insure against distortion or crushing of the parts as the medium dries and contracts.
With some specimens (particularly chernetids), the detailed morphology of the chelicerae is best studied before the cover glass is applied. Under these circumstances, the chelicerae may be moved about at will, so that the tips of the setae, the flagellum, the serrulae, and the galea can be examined carefully.
It is wise to use thin microscope slides (less than one millimeter in thickness), so that the specimen may be examined from both sides under high magnification.
Measurements should be made using an ocular micrometer, following the directions in Chamberlin (1931, p. 23-25).

I might state that each method here treated is a compound of other, previously used by other taxonomists, and that each specific method is not the best -- instead the combination of all of them.