Cooley dc Kohls: Argasidae of N. America, etc. 11 



Family, Argasidae Canestrini, 1890 



Non-scutate Ixodoidea with sexual dimorphism slight. Integument of adults 

 and nymphs leathery, wrinkled, granulated, mammillated or with tubercles. 

 Capitulum in adults and nymphs either subterminal or distant from the anterior 

 margin; in larvae subterminal or terminal. Capitulum, especially in depleted 

 adults and nymphs, in a more or less marked depression (camerostome) . Artic- 

 ulations of the palpi of all stages free (never fused) . Porose areas absent in both 

 sexes. Eyes when present placed on the supracoxal folds. Spiracles in adults and 

 nymphs usually placed anterior to coxae IV. Pulvilli usually rudimentary or 

 absent in adults and nymphs; sometimes well developed (functional) in larvae. 

 Nymphal stages plural and the number variable. 



Type genus, Argas Latreille, 1796. 



The number of genera that should be recognized in the Argasidae has long 

 been a matter of doubt. Nuttall et al. (1908) and Neumann (1911) recog- 

 nized Argas and Ormthodoros, although Nuttall stated that "we are by no 

 means sure that the family Argasidae contains more than one genus, Argas." 

 Banks (1912) erected the genus Otobius for a species formerly included in 

 Ormthodoros. This we recognize as valid. 



Pocock (1907) advocated the revival of Carios Latreille, 1796 for Argas 

 vespertdioms, an Old World species associated with bats, because this species 

 possesses a "conspicuous transverse, lightly curved groove just behind the anus." 

 As pointed out by Nuttall, this structure is not peculiar to vespertilionis. It is 

 present in other species also, though modified, and is the character usually 

 referred to as the transverse postanal groove. However, the species is aberrant. 

 The capitulum is situated far forward and would be visible from above were it 

 not for the prominent hood. The sutural line on the margins of the body, a 

 character used by Neumann (1911) to characterize the genus Argas, is absent. 

 Yet by the other characters it appears to be clearly an Argas, and until further 

 information is available, we consider it best to refer the species to this genus. 



Also in 1907 Pocock erected the genus Alectorobius for Ormthodoros talaje 

 on account of the presence of lateral wings (cheeks) on the camerostome. If 

 Alectorobius were to be reestablished, it would be desirable to find correlating 

 characters. While talaje and some other known species have cheeks, dorsal 

 humps on the tarsi, and micromammillae on the legs, certain species lack the 

 dorsal humps or the micromammillae, or both. 



The New World species of Argas and Ornithodoros can best be distin- 

 guished by the presence of the sutural line in the former, its absence in the 

 latter. Bedford (1932) made Ormthodoros Koch a synonym of Argas, stating 

 that he could not consider "having the margin of the body differing in structure 

 from the rest of the integument" as being of generic importance. He was influ- 

 enced in his decision by Ornithodoros perengueyi Bedford and Hewitt, 1925. 

 In this species, as well as in O. dunm Matheson, 1935 and O. stageri Cooley 

 and Kohls, 1941, the flattened margins persist even in well fed specimens but 

 the sutural line is absent. While these species serve to show that the genera 



