A. variegatum has been foiind from sea level to 85OO feet 

 elevation. In the Yemen (Arabia), this species is conraon on 

 cattle in well vegetated valleys and hillsides between 25OO and 

 5000 feet elevation, but absent in deserts at lower elevations 

 and rare in more barren higher elevations (Hoogstraal, ms.). 

 Franchini's (1930) record of A. variegatum from Hodeida, on 

 Yemen's coastal plain, is due^either to erroneous locality labels 

 or represents specimens from highland cattle arriving for slaugh- 

 ter. This species is common at Asmara, Eritrea, 7500 feet eleva- 

 tion (HH collecting), but Schoenaers (1951B) states that it does 

 not occur over 2000 meters (65OO feet) elevation in Ruanda-Urundi . 



In East and Central Africa, Wilson (1953) has nicely defined 

 the presence of two very distinct ecological relationships between 

 ticks and cattle. One of these, the P.. a ppendiculatus -A. variegatum 

 association, occiirs in areas with rainfall well above 25 inches per 

 annum (and is of considerable importance in relation to East Coast 

 fever and heartvmter transmitted to cattle by the respective ticks). 

 The second, the R. pravus (= R. neavi)_A. gemma association, occurs 

 where rainfall very seldom exceeds twenty or 25 inches per annum 

 (and is of negligible veterinary importance). For a summary of 

 Wilson's second association, see R. pravus (page 68I). 



The distribution of the R. appendiculatus -A. variegatum asso- 

 ciation corresponds to what veterinaxians previously referred to 

 as '"dirty areas"' (i.e. East Coast fever endemic areas). As stated 

 above, rainfall here is at least 25 inches annually, usually well 

 above this figure, and falls below this level only once in every 

 twenty or 25 years. This association includes the highlands of 

 Kenya and Tanganyika, a 25 to thirty mile belt bordering Lake 

 Victoria in Kenya, Uganda, and Tanganyika, and continues down the 

 Rift Valley in the country adjacent to Lake Tanganyika and Lake 

 Nyasa, and (a short distance) into Mozambique. It also includes 

 the hujoid seacoast plains, which are only a few miles wide in 

 Kenya but much wider in Tanganyika. Within drier areas (i.e. 

 those of the first association) are isolated islands in the "rain 

 shadow"' of hills and mountains where higher precipitation results 

 in more dense vegetation than that of the surrounding plains. In 

 these islands, the R. appendiculatus -A. variegatum association 

 persists. The soil~and vegetation on v;hich this association oc- 

 curs vary tremendously with slope of terrain, altitude, underlying 

 rock formation, and temperature. The single comiron factor in their 



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