AMBLYOMMA INTRODUCTION Of about a hundred Amblyomma species in the world, some twenty occur in Africa and eight in the Sudan. The specific identity of most common African species appears to be settled and only in exceptional instances are specimens likely to be confused. One of the chief remaining taxonomic problems among common African amblyom mas is the A. marmoreum group, in which the range of species varia tion needs to be determined for several somewhat differing forms. Observations from the present study indicate need for further research on the relationship between A. variegatum and A. pomposum and suggest that the latter may be no more than a subspecies of the former. Recently a few workers have designated certain African populations by subspecific ranks that challenge further investigation. Several West African species are known from so few specimens that their validity is questionable. This genus has been the subject of an extensive review by Robinson (1926) comprising volume four of Nuttall's Monograph on Ticks. The African species have been keyed by Rageau and Vervent (1953). The immature stages of most African amblyommas remain to be described with satisfactory criteria for distinguishing them. Economically, two African species have thus far been shown to harbor or transmit human disease organisms. A. hebraeum is considered an important boutonneuse fever ("tick typhus vector in South Africa and A. variegatum has been found naturally in fected with Q fever In French Equatorial Africa near the Sudan border. Several species are important transmitters of veterinary diseases, cause damage to animal skins, or debilitate animals through the volume of blood withdrawn or by initiating wounds that develop into ugly secondary sores. Biologically, many gaps exist in our knowledge of African Amblyomma distribution, host-preferences, especially of immature stages, and life history. Birds are important immature stage hosts but the full extent of their importance as hosts remains to be studied. Nymphal preferences may differ from those of adults, although in some species this may not be true. Host size appears to be of some importance, for most larvae parasitize small animals; nymphs attack larger animals; and adults feed on the largest available animals, except carnivores. Immature stages, however, more frequently parasitize carnivores. Cattle and, to some extent, other domestic animals are important adult hosts and wild ante lopes are also frequently parasitized. The African tortoise, rhinoceros, elephant, and buffalo harbor species mostly restricted to themselves. In general, the domestic animal parasitizing species are well represented in study collections; others are seldom collected. Amblyomma ticks are usually three-host parasites and, so far as known in Africa, there is usually only a single generation an nually. KEY TO SUDAN SPECIES OF AMBLYOMMA MAIES 1. Lateral grooves extending anteriorly at least to middle of scutum.. Lateral grooves absent...... 2. Eyes small, hemispherical, situated in Eyes flat or very slightly convex, not in a depression...... 3. Festoons with two colors. (Scutal ornamentation always as illustrated)... Festoons only dark colored... .2 .7 .3 ..5 ......A. LEPIDUM Figures 68 and 69 ..4 4. Scutum with numerous coarse punctations, Scutum smooth, with few scattered coarse 5. Scutum smooth, with only very fine punctations. Eyes slightly convex. (Chiefly from buffalo).... Scutum with scattered large punctations. 6. Smaller than A. marmoreum group, maximum size 5.5 mm. x 4.5 mm. Dark scutal areas more widely separated by pale ...A. POMPOSUM Figures 80 and 81 ...A. VARIEGATUM Figures 92 and 93 .A. COHAERENS Figures 64 and 65 ..6 areas than in A. marmoreum (see Figures).........A. NUTTALLI 3. Scutum narrowly rounded posteriorly; large punctations chiefly in medio lateral area, more or less confluent.... Scutum more widely rounded posteriorly, 4. Scutum with central and lateral areas largely pale colored; punctations either large or fine... Scutum with either central or lateral areas largely dark colored; punctations only fine.... 2 .......4 ....A. POMPOSUM Figures 82 and 83 3 .A. LEPIDUM Figures 70 and 71 ..A. VARIEGATUM Figures 94 and 95 ..5 .......7 |