76 



Acarology 



infestation by raillietids. R. amis passes the larval stage within the egg 

 and nymphs or eggs containing nymphs are liberated by the females. 



Rejerences: 



Hirst, S. 1922. Mites injurious to domestic animals. Brit. Mus. (Nat. Hist.) 



Econ. Ser. 13:1-107. 

 Radford, C. D. 1938. Notes on some new species of parasitic mites. Para- 



sitol. 30:427-440. 



Halarachnidae Oudemans, 1906 



Figure 58 



Diagnosis: Halarachnids are endoparasites in the respiratory passages 

 of mammals. They appear to represent an extreme modification of the 

 laelaptid mites. Their body shape varies from oval {Pneumonyssus) 

 to wormlike {Orthohalarachne attenuata) . The dorsal plate is reduced 



Figure 58 Pneumonyssus simicola Banks, 1901. Ventral view of male (right), 

 female (left), and dorsal view of female (center). (After Vitzthum 1931) 



and undivided, the tritosternum is absent, and the sternal plate is re- 

 duced. Only three pairs of sternal setae are present. The genital plate 

 of female is rudimentary, while the male genital opening is in the 

 anterior margin of the sternal plate. The anal opening is posterior on 

 an anal plate that bears three or four setae. Stigmata with small peri- 

 tremes lateral to the region of coxae iv are present. The tectum is 

 simple and triangular, while the hypostome is triangular and pilose. 

 Chelicerae with the movable digit more strongly developed than the 

 fixed digit are present. The palps have four segments. Forked hair 



