A typical male, measioring some 3.0 mm. long, is pale yellow, 

 brown, or reddish brown; has a pearshaped body; slightly convex 

 scutum; deep lateral grooves and distinct festoons; a narrowly 

 elongate or oval but medially expajided, deep posteromedian 

 groove; shorter and broader but equally deep paramedian grooves; 

 very slightly convex eyes; sharply angiolar basis capituli; elon- 

 gate, angular, adanal shields that in the posterior half of 

 their length are usually distinctly widened and anteriorly are 

 elongately subtriangular; and fairly distinct accessory shields. 



Scutal pujictations always consist of four regular or irregular 

 rows of fairly large more or less discrete piinctations, among which 

 a variable number of small to large interstitial punctations are 

 indiscriminately scattered. 



If the specimen is engorged, the pearshape of the body is 

 frequently exaggerated by integumental bulging laterally and 

 posteriorly, from eye to eye, and the legs are successively larger 

 from the anterior to the posterior pair; the posterior pairs are 

 often massive and armed with a formidable tarsal hook ventrally. 



The single character that most frequently confuses identity 

 of this species is the density and size of interstitial ptmcta- 

 tions. The general conception of this species is one of a tick 

 with four more or less definite rows of larger punctations among 

 which rather few and smaller insignificant punctations are pro- 

 miscuously scattered. This form (Figure 289) is fovind throughout 

 northern Sudan and Egypt, bxit in southern Sudan occurs, to the 

 best of oTir knowledge, only on larger groxondfeeding birds, such 

 as biostards and storks . In typical southern Sudan specimens, 

 interstitial punctations are larger, deeper, and more numerous 

 (Figiire 293). If it were not for the four rows of largest 

 punctations, one would be tempted to refer to much of this 

 material as R. sulcatus (as, indeed, some students of African 

 and South American ticks are doing). In central Sudan, most 

 specimens are fairly heavily punctate. (Although we have large 

 files of notes on variation among specimens from throughout the 

 world, a further disciission of this matter shoiild await a thor- 

 oughly exhaustive study) . 



Spiracular plates in this species are surprisingly variable. 

 These differences appear to be often correlated with nutrition 



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