The Argasidac of North America, Central 

 America and Cuba 



Introduction 



The taxonomic study of the Argasidae has been beset with difficult 

 problems, some of which are stil! unsolved. The principal difficulty has been 

 and still is the lack of adequate generic characters. Some of the earlier species 

 were described from very few specimens and frequently with very little knowl- 

 edge of their biologies. By 1908, Neumann and Nuttall had notably improved 

 the situation by better generic definitions and the use of new specific characters. 

 Both retained as genera only Argas and Ornithodoros. In 1912 Banks added 

 the genus Otobtus, and in 1942 Antricola was added by the authors. 



In 1908 only some twenty species were known. Now in North America 

 alone there are at least twenty-five species and about thirty new species have 

 been described from other countries. The characters exhibited by these new 

 species have served to clarify certain of the taxonomic problems; they have 

 made others more confusing. Some specific distinctions have found corrobora- 

 tive support in the biologies. With the increasing number of new species, it 

 has become more and more difficult to separate Argas and Ornithodoros and 

 we have found it necessary to change the previous conceptions of these genera. 

 However, no genera have been synonymized. It is probable that subsequent 

 workers will find others necessary but it is earnestly hoped that none will be 

 erected until reliable generic criteria have been clearly established. The present 

 names serve the purpose and should be changed only for permanent reasons. 



In a previous paper 1 the senior author emphasized the importance of 

 variation within species. This occurs principally in the ornamentation, and 

 the morphology is reasonably constant. In the Argasidae it is perhaps too 

 early to evaluate fully the variation within species, but at least it is evident 

 that it is of little importance in the genus Ornithodoros. Ornamentation is 

 absent in the known species of the Argasidae except in Ornithodoros coriaceus. 



Where confusion has arisen in specific identities, it has been due largely 

 to overlooking characters in the mammillae and hypostome, some of which 

 are not very easily detected, and the very distinct ones found in the larval 

 stage which heretofore has not been thoroughly studied. 



Host specificity varies in the numerous species. So far as known several 



1 CoOLEY, R. A. The Genera Dermacenlor and Otocenlor (Ixodidae) in the United 

 States, with studies in variation. National Institute of Health Bulletin No. 171, Gov- 

 ernment Printing Office, 1938. 



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