392 Acarology 



Pteromorphs attached to both hysterosoma and propodosoma, 

 covering pseudostigmata and even pseudostigmatic organs and 

 good portion of propodosoma; with small pteromorphs not 

 directed ventrally; with two pairs of genital setae Oripodidae 



23. Pteromorphs extending well past anterior margin of hysterosoma 24 

 Pteromorphs not extending past anterior margin of hysterosoma 25 



24. Pteromorphs extending anteriorly but not ventrally from place of 

 insertion; lamellae may be large but not spectacularly so 



Tenuialidae 



Pteromorphs extending well anteriorly past anterior margin of 

 hysterosoma and strongly curving ventrally; lamellae cover pro- 

 podosoma Notaspididae 



25. Pteromorphs not large nor curvmg ventrally 26 

 Pteromorphs large and curving ventrally; lamellae cover pro- 

 podosoma Oribatellidae 



26. Lamellae not covering most of propodosoma; chelicerae normal, 

 without processes 27 



Lamellae covering most of propodosoma; fixed chela of chelicerae 

 with forward-directed hornlike process Microzetidae 



27. Pteromorphs in one plane only, not curving ventrally; with four 

 pairs of genital setae in adults Oribatulidae 



Pteromorphs curving ventrally; with six pairs of genital setae in 

 adults Ceratozetidae 



28. Pteromorphs not extending anterior or posterior to line of attach- 

 ment (hinge) to body 29 



Pteromorphs extending anteriorly and posteriorly to line of at- 

 tachment to body 30 



29. Genital plates with five pairs of setae (occasionally four accord- 

 ing to Vitzthum) ; chelicerae normal, strong; interlamellar setae 

 normal Haplozetidae 



Genital plates with six pairs of setae; chelicerae (except in Pro- 

 pelops) long, slender, with minute shears; interlamellar setae may 

 be normal, missing, or spatulate Pelopidae 



30. Lamellae not covering much of propodosoma 31 

 Lamellae covering most of propodosoma; genital plates with five 

 pairs of setae; anterior pair of circumanal setae next to anterior 

 end of anal opening Epactozetidae 



