NEW GENERA AND SPECIES OF PARASITIC MITES OF 

 THE SUPERFAMILY PARASITOIDEA 



By H. E. EwiNG 



Bureau of Entomology, United States Department of Agriculture 



Parasitic mites of the superfamily Parasitoidea have long been 

 recognized as of economic importance. In fact, one species, the 

 common chicken mite, Deivnanyssus gallinae, was studied and de- 

 scribed by Redi in the seventeenth century. That these mites may 

 be agents in the transmission of disease was demonstrated some years 

 ago in the case of the common rat mite, Echmolaelaps ecMdninus 

 (Berlese), which was shown to transmit a disease-producing proto- 

 zoan among white rats. Recently another species, the tropical rat 

 mite, Lipoiiyssus hacotl (Hirst), has been implicated in the transmis- 

 sion of a disease of man, endemic typhus. 



A study of the 15 species described as new in this paper has thrown 

 much new light on generic characters in the group; in fact, it has 

 resulted in the description herein of five new genera and a rede- 

 scription of six old ones. The separation of certain members of 

 the familjT^ Dermanyssidae from those of Parasitidae has always 

 been difficult. It is here suggested that as far as the mouth parts 

 are concerned the dividing point between the two families be based 

 upon the presence on the chelicerae of either true teeth or cheliceral 

 setae. If either one of these characters is present, the genus should 

 be placed in the Parasitidae; if both are absent, it should be placed 

 in the Dermanyssidae. 



Family PARASITIDAE 

 Subfamily Laelapinae 



ACANTHOCHELA, new genus 



Body thickly beset with short and rather stout setae. Fixed arm 

 of chelicera with several recurved, fanglike setae. Ventral plates 

 of female as follows: Sternal plate about as broad as long and 

 provided with many setae and two pairs of pores in the form of 

 slits; genito ventral plate of moderate size, not reaching to the anal 

 plate, and 3-lobed posteriorly; anal plate longer than broad, broadly 



No. 2971.— Proceedings U.S. National Museum. Vol. 82. Art. 30 



177444—33 1 1 



