116 Classification of Ixodidae 



CLASSIFICATION OF THE IXODIDAE. 



There are nine genera: Ixodes, Haemaphysalis, Dermacentor, 

 Rhipicentor, Rhipicephalus, Margaropus, Boophilus, Hyalomrna and 

 Amblyomma (including the sub-genus Aponomma). They present 

 varying degrees of affinity, which may be indicated by arranging them 

 into groups according to the following scheme : 



Ixodidae 



i , 



Prostriata Metastriata 



i 



Brevirostrata Longirostrata 



~i i" 



Group 1 Group 2 Group 1 Group 2 



I I > J 



1. Ixodes 2. Haemaphysalis 3. Dermacentor 8. Hyalomma 9. Amblyomma 



4. Rhipicentor (Aponomma) 



5. Rhipicephalus 



6. Margaropus 



7. Boophilus 



Ixodes is clearly marked off from the other genera by a number of 

 characteristics, of which the most striking are the anal groove sur- 

 rounding the anus in front {Prostriata) and the absence of festoons. 

 The remaining genera fall naturally into two divisions: the one 

 characterized by a comparatively short, and the other by a comparatively 

 long capitulum. Occasionally, forms are encountered which are aberrant 

 in this respect. 



SECTION I. PROSTRIATA. 



With anal grooves surrounding the anus in front. 



Genus (1) Ixodes: inornate, without eyes and without festoons; 

 spiracles round or oval ; palps and basis capituli of variable form ; coxae 

 either unarmed, trenchant, spurred or bifid ; tarsi without spurs. Sexual 

 dimorphism pronounced, especially with regard to the capitulum ; in the 

 </ the venter is covered by non-salient plates : one pregenital, one median, 

 one anal, two adanal and two epimeral plates. Figs. 115-119. 



Type species : Ixodes ricinus (Linnaeus). 



