J 48 Acarology 



and all tarsi have rayed claws. The genitalia are situated on the ante- 

 rior, ventral portion of the body just behind the legs and the genital 

 plate is a transverse rather than a longitudinal slit. Palpi are short and 

 simple. The chelicerae are short and stylet-like for piercing. The anal 

 opening is on the posterior of the body. These mites are either free- 

 living on plants or gall makers. Vitzthum divides this group into the 



Eriophyidae and Phyllocoptidae, 

 but Keifer's single-family arrange- 

 ment is followed here. 



Although the Eriophyidae have 

 been separated from the prostig- 

 matic mites and placed in a sepa- 

 rate group, the Tetrapodili, their 

 relationship to the normal eight- 

 legged mites can be demonstrated. 

 In certain of the normal groups 

 some genera begin to lose a pair 

 of legs, as in the Podapolipodidae 

 which are parasitic on insects. 

 This is not surprising since the 

 mode of life in this family would 

 tend towards a parasitic baglike 

 mite. In the Phytoptipalpidae, 

 which are plant feeders and are 

 closely related to the Tetranychi- 

 dae, one genus, Phytoptipalpus, 

 possesses only three pairs of legs. 

 In this same family, Tenuipalpus 

 eriophyoides Baker (nymph), al- 

 though possessing four pairs of legs, is very elongated and annulate, 

 greatly resembling an eriophyid mite. The transverse genital plates 

 also indicate the relationship of the Eriophyidae to the Phytoptipalpi- 

 dae, since these two families are the only ones which possess this type of 

 organ, other genital openings being longitudinal. The genitalia of the 

 Eriophyidae is located just behind the legs, far anteriorly, while that of 

 the Phytoptipalpidae is at the rear of the body. This difference is not as 

 significant as may be presumed since there probably has been a coalesc- 

 ing of body segments posteriorly in the phytoptipalpid type which gives 

 the appearance of having the genitalia on the extreme end rather than 

 in a more or less normal position. The rayed tarsal appendage of the 



Figure 106 Oxypleiirites ciesciilifoliac 

 Keifer. Egg, two nymphal, protogyne, 

 and deutogyne stages. (After Keifer 

 1942) 



