COLLECTING AND PRESERVATION 



A variety of methods may be used to collect specimens for qualitative 

 purposes. None requires elaborate apparatus or an involved technique; 

 freshwater asellids are easily-seen, macroscopic animals that are rela- 

 tively slow-moving, do not swim, and dwell amongst submerged vegetation 

 and bottom detritus. They are not conspicuous burrowers, although they 

 may often occur on the undersurfaces of submerged stones. 



The most straightforward method is the direct removal by the investiga- 

 tor of small amounts of submerged vegetation or bottom material either 

 by hand or using a fine-meshed (scrim) dipnet or pondnet followed by the 

 searching of this material for specimens. If asellids occur they may be 

 handled by gripping the middle of their body with a pair of blunt forceps 

 held at right-angles to the long axis of the body. Searching may be 

 facilitated by placing the vegetation or other material to be examined 

 into a white, shallow dish or tray containing water to a depth of about 

 one inch. A tray normally used by the author measures 8 x 10 x 3 inches. 

 If the material is slightly teased apart after being placed in the tray 

 and is then undisturbed for a minute or so, specimens often become con- 

 spicuous by their slow movements amongst the material or by their move- 

 ment from the material towards clear areas of water in the tray. Such 

 specimens may also be removed by forceps, but a better, less damaging 

 method is to suck them gently with some water into a glass tube (diameter 

 about 3/8 inch) in which suction is maintained by a rubber bulb attached 

 to one end. A little practice on the part of the operator is required 

 with this tube method of handling specimens for satisfactory performance. 

 Asellids may also often be collected by removal of submerged stones and 

 the examination of their lower surfaces. 



Specimens are best killed and preserved by directly placing them in 70- 

 80% ethyl alcohol. Transference to fresh alcohol after a few days is re- 

 commended. Care should be exercised to ensure that crowding of preserved 

 specimens does not occur, and that tubes are adequately labelled. The 

 maintenance of live specimens is not required for species identification. 



It should be stressed that reasonably large collections are necessary for 

 adequate systematic examination since species identification (for both 

 Asellus and Lirceus) is based on adult males only, and more than one 

 species may occur in the same collection. Liraeus and Asellus may also 

 occur together. It is suggested that 25 specimens be regarded as the min- 

 imal adequate number for one collection, although, of course, smaller 

 collections will often be useful also. 



