12 Acarology 



abdomen, and in some the abdomen appears to be segmented. Evi- 

 dence of primary segmentation is found in the primitive Notostigmata. 

 Some of the tarsonemids appear to have posterior segments but these 

 are probably secondary rather than primary. 



Vitzthum 1940 divides the body of acarinids according to the fol- 

 lowing chart (Figure 5) : 



Gnathosoma 



) Propodosoma — jj 

 Metapodosoma 



Opisthosoma 



Region of the 

 oral opening and 

 the mouth parts 



Gnathosoma 



Figure 5 Schizotetranychus schiz- 

 sopus (Zacher), 1913 showing the 

 arbitrary divisions of the body. 

 (After Vitzthum 1940) 



*Proterosoma 



Region of legs Propodosoma 

 I & n 



Region of legs Metapodosoma 



III & IV 



Posterior region Opisthosoma 



Podosoma 



^Prosoma 



Idiosoma 



) 



\YiysX' 

 J 



erosoma 



Andre and Lamy 1937 review the opinions on the primary metamer- 

 ism of the acarinids and following Henking 1882 and Oudemans 1909 

 state that there are thirteen metameres in most of the mites. The ven- 

 tral parts of three segments are fused to form the gnathosoma. The 

 first or pre-oral segment bears no appendages, the second bears the 

 chelicerae, and the third the pedipalps. The podosoma consist of the 

 dorsal parts of the first three segments and all of the next four seg- 



