CHAPTER IV 



The Suborder Ixodides Leach, 1815 



THE Ixodides or ticks are all parasitic. Ticks as well as being simi- 

 lar in habits also have many morphological features in common, 

 such as a piercing hypostome with recurved teeth, chelicerae with lat- 

 eral teeth on the movable digits, a pitlike sensory organ on tarsus i 

 (Haller's organ), large size, and lateral stigmata without sinuous peri- 

 tremes. Although ticks are similar to mesostigmatid mites there is no 

 group of species intermediate between the two. It therefore seems 

 desirable to consider the ticks as a separate suborder. 



Vitzthum 1941 divides the Ixodides into three subgroups each of 

 which is represented by a single family. Rather than introduce group 

 names, these will be ignored. 



No special discussion of the morphology of ticks will be needed for 

 the understanding of the key to families. 



Key to the Ixodides 



1. Scutum present in all stages 2 

 Scutum absent in all stages Argasidae 



2. Palpal tarsus terminal in position; scutum similar in texture to 

 unmodified integument in females Nuttalliellidae 



Palpal tarsus imbedded in ventral apex of tibia; scutum of differ- 

 ent texture than unmodified integument Ixodidae 



Argasidae G. Canes trini, 1890 



Figure 103 



Diagnosis (from Cooley and Kohls 1944) : The argasids are non- 

 scutate Ixodides with slight sexual dimorphism. Both adults and 



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