Mesostigmata 77 



which has two tines is present on the palpal tarsus. All legs are pro- 

 vided with pretarsi, caruncles, and claws. 



Genera: 



1. Halarachne Allman, 1847 



Type. Halarachne halichoeri AWmsin, 1847 (= Rhinixodes l^ehring, 

 1884 and Rhinacarus Nehring, 1884) 



2. Pneumonyssus Banks, 1901 {— Pneumotuber Landois and Hoepke, 



1914) 

 Type. Pneumonyssus simicola Banks, 1901 



3. Orthohalarachne Newell, 1947 



Type. Halarachne attenuata Banks, 1910 



Discussion: Newell 1947 has given an excellent account of the mor- 

 phology and systematics of this family. His paper forms the basis for 

 most of the following discussion, although other authors have been 

 consulted. 



Halarachnids live in the air passages of mammals. Their life cycles 

 are unknown but a few pertinent facts concerning their biology have 

 been observed. Doetschman 1944 and others have found the six-legged 

 larvae associated with the adult males and females. No nymphs be- 

 longing to this family have been seen. It should, however, be kept in 

 mind that the life history has not yet been observed in its entirety and 

 the methods by which new hosts are invaded have not yet been deter- 

 mined. The genus Halarachne is found exclusively in the respiratory 

 passages of seals of the family Phocidae, the Orthohalarachne para- 

 sitize the other families of the Pinnipedia, and Pneumonyssus is found 

 in apes, dogs, and other mammals. 



Although infection with species of Pneumonyssus is fairly common 

 in some primates, no human infections have been discovered. Human 

 pulmonary acariasis is a common ailment in some areas such as parts 

 of India, and during World War II the syndrome produced by infec- 

 tion of human respiratory passages with mites was known as Tropical 

 Eosinophilia. The mites that were recovered were not halarachnids, 

 but common, free-living species. 



References: 



Carter, Henry F. and V. St. E. D'Abrera. 1946. Mites (Acarina) — a prob- 

 able factor in the aetiology of spasmodic bronchitis and asthma asso- 

 ciated with high eosinophilia. Trans. Roy. Soc. Trop. Med. & Hyg. 

 39:373-395. 



