124 Annals Entomological Society of America [Vol. X, 



cc. Abdomen without posterior lobes. 



d. Al:)domen with prominent marginal seta-bearing tubercles, sometimes 



only behind Nothrus Koch, 1835 



[Type: A^. spiniger Koch] 



dd. Abdomen without seta-bearing tubercles Gymnonothrus n. gen. 



[Type: Nothrus sylvestris Nicolet] 



Key to the Genera of Stihfamily Lohmannince. 



a. Abdomen subcylindrical; tarsal claws either monodactyle or bidactyle. 



b. Tarsal claws monodactyle Lohmanniai« Michael, 1898 



[Type: L. paradoxa (Haller)] 



bb. Tarsal claws bidactyle Eulohamannia" Berlese, 1910 



[Type: -E. ribagai Berlese] 

 aa. Abdomen oval, not cylindrical; tarsal claws tridactyle. 



b. Abdomen never divided by a transverse suture above; integument tubercu- 



late; claws homodactyle Tumidalvus" Ewing, 1908 



[Type: T. americana Ewing] 

 bb. Abdomen sometimes divided above by a transverse suture; integument 

 not tuberculate; claws sometimes heterodactyle, 



Trhypochthonius Berlese, 1904 

 [Type: T. tectorum, Berlese] 



Family Hypochthonid^. 



Key to the Genera of Subfamily Hypochthonina. 



a. Abdomen divided into two parts dorsally by a transverse suture. 

 b. Tarsal claws tridactyle; cephalothorax truncate in front, 



Parhypochthonius Berlese, 1904 

 [Type: P. aphidinus Berlese] 

 bb. Tarsal claws mondactyle. 



c. Abdomen spherical; dorsal surface tessellated, 



Sphaerochthonius Berlese, 1910 

 [Type: S. splendidus (Berlese)] 

 •cc. Abdomen not spherical; dorsal surface not tessellated. 



d. Abdomen clothed with leaf-like setce; shoulders each with a seta- 

 bearing tubercle Malacoangelia Berlese, 1913 



[Type: M. remigera Berlese] 

 dd. Abdomen clothed with setiform hairs; shoulders without seta-bearing 



tubercles Hypochthonius Koch, 1835 



[Type: H. rufulus Koch] 

 aa. Abdomen divided dorsally into three or more parts by transverse sutures. 

 b. Abdomen clothed with moderate simple setae. 



c. Integument of dorsum of abdomen reticulate; body short. 



Brachychthonius Berlese, 1910 

 [Type: B. brevis (Michael)] 

 cc. Integument of dorsum of abdomen smooth; body long, 



Arthrochthonius n. gen. 

 [Type: A. palliduliis (Koch)] 

 bb. Abdomen bearing some large (enormous) pectinate, foliaceous, or plumose 

 setae. 

 c. Body clothed with large, broad, leaf-like or fan-like setaj, 



Pterochthoniusi^ Berlese, 1913 

 [Type: P. angelus Berlese] 



16 = the old Michaelia, which name was shown to be preoccupied by Michael. 



"Erected as a subgenus bv Berlese. 



i^Berlese claims, "Acari Nuovi," Manipulus VI, 1910, that my genus Tumidal- 

 vus is a synonym of his Trhypochthonius, 1904. I hold it to be distinct for reasons 

 shown in the above ke3^ 



i^Erected bv Berlese as a subgenus. 



