Trom b idi formes 1 73 



22. Movable chela straight, stiff, of varying lengths, no stylophore 

 (mandibular plate) 23 



Movable chela long, whiplike, curving within body; basal che- 

 liceral segments fused and form stylophores (mandibular plates); 

 without crista and with lenslike eyes; no genital suckers (Phytopti- 

 palpidae related to this family but do not possess thumb-claw 

 process on palpus) Tetranychidae 



23. Chelicerae long, slender, capable of being withdrawn deeply into 

 the body; dorsal sensory areas and sensory setae present 24 

 Chelicerae short and not capable of being extended to such ex- 

 tent; with M-like prominent peritreme on gnathosoma; no dorsal 

 sensory areas; with large pincer-like palpi for grasping Cheyletidae 



24. Without genital suckers; with sensillary area and/or crista 25 

 With genital suckers; no sensillary areas; palpi small, entire mouth 

 parts capable of being withdrawn into body cavity Calyptostomidae 



25. Mouth parts small, capable of being withdrawn into the body; 

 propodosoma usually drawn out into long nose Smaridiidae 

 Mouth parts large, not capable of being withdrawn into body; 

 propodosoma not drawn out into long nose or snout Erythraeidae 



26. Without strong body armor; with normal leg setae 27 



With several strongly sclerotized dorsal plates; legs i and ii, espe- 

 cially I, with several large spines on tubercles giving rake effect 



Caeculidae 



27. Palpal thumb not large; inconspicuous, at times hard to see 28 

 Palpal thumb large and conspicuous 29 



28. With three pairs of genital suckers; dorsal sensory setae in some 

 cases set in characteristic pits or pseudostigmata; tarsal claws 

 large, serrate Teneriffiidae 

 Without genital suckers; no specialized sensory setae on dorsum; 

 tarsal claws not serrate; usually modified to live beneath scales of 

 lizards; no suture between propodosoma and hysterosoma 



Pterygosomidae 

 Without genital suckers; two pairs of sensory setae on propodo- 

 soma; with tarsal suckers or claws; free-living; body divided by 

 suture Pseudocheylidae 



29. Palpal tarsus ventral 30 

 Palpal tarsus distal; large red mite, with radiating legs; free peri- 

 tremes Anystidae 



