Australian Arrenurus 
Genital plates narrow (about half the length of 
genital valve) (Figure 60)... 
. A. purpureus sp. nov. 
25. Posterior margin of genital plates directing 
laterally .....26 
Posterior margin of genital plates sloping 
posteriorly.27 
26. PIV stocky, posterior margin of genital plates 
with a straight posterior margin (Walter 
1929, figure 33, 34)... A. harpagopalpus Walter 
PIV not stocky and not tapering (Cook 1986, 
figure 1643), posterior margin of genital 
plates rounded (Cook 1986, figure 1638). 
. A. margatellus Cook 
261 
27. Body colour blue.28 
Body colour brownish yellow-orange.29 
28. Dorsal shield relatively small, ratio body 
length/length of dorsal shield 1.58-1.70. 
... ....A. caeruleus sp. nov. 
Dorsal shield relatively large, ratio body 
length/length of dorsal shield 1.39-1.48. 
. A. ihienemanni K.O. Viets 
29. Body length > 1000 pm, genital plates laterally 
angular (Figure 46). A. vanderpalae Smit 
Body length < 1000 pm, genital plates laterally 
rounded (Figure 34). A. gilvus sp. nov. 
Manuscript received 15 January 1996 ; accepted 3 July 1996. 
