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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 antelopes are also frequently parasitized. The African tortoise, rhinoceros, elephant, and buffalo harbor species mostly restricted to themselves. In general, the domestic animal parasitizing spe cies 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.

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2. Eyes small, hemispherical, situated in

a well defined depression (i.e. orbited).....

Eyes flat or very slightly convex, not in a depression..

3. Festoons with two colors. (Scutal ornamentation always as illustrated)..

Festoons only dark colored...

....3

..5

.A. LEPIDUM Figures 68 and 69

..4

4. Scutum with numerous coarse punctations, and with a red lateral spot. (Rare in Sudan)....

Scutum smooth, with few scattered coarse
punctations or none; usually without red
lateral spot. (Common in Sudan)...

5. Scutum smooth, with only very fine punctations. Eyes slightly convex. (Chiefly from buffalo)...

Scutum with scattered large punctations.
Eyes flat. (Chiefly from cold-blooded
vertebrates).

6. Smaller than A. marmoreum group, maxi-
mum size 5.5 mm. x 4.5 mm. Dark scutal
areas more widely separated by pale
areas than in A. marmoreum (see Figures)....

Size at least 6.0 mm. x 5.0 mm. Dark
scutal areas less widely separated from
each other by pale areas than in A.
nuttalli..

7. Scutum dark, ornamented areas small, punctations only small. (Medium size, drab tick, chiefly from elephants)...

Scutum extensively ornamented, some
large punctations present. (Very
large, colorful tick, chiefly from
rhinoceros)..

.A. POMPOSUM

Figures 80 and 81

..A. VARIEGATUM Figures 92 and 93

....A. COHAERENS Figures 64 and 65

...6

....A. NUTTALLI Figures 76 and 77

..A. MARMOREUM Figures 72 and 73

.A. THOLLONI Figures 88 and 89

.A. RHINOCEROTIS Figures 84 and 85

FEMALES

1. Eyes in a well-defined depression (i.e. orbited), hemispherical or strongly convex.

Eyes not in a depression, flat or
slightly convex.......

2. Scutal punctations very coarse, uneven,
some confluent; surface rugose poste-
riorly; ornamentation absent or con
sisting of only a small pale area in
posterior field; length often no
greater than width. Eyes may be
convex but not hemispherical. (Ex-
tremely rare in Sudan).

Scutal punctations not so coarse, sur-
face not rugose, pale areas more ex-
tensive (unless faded). Eyes hemis-
pherical. (Common)....

3. Scutum narrowly rounded posteriorly; large punctations chiefly in medio lateral area, more or less confluent.

Scutum more widely rounded posteriorly,
large punctations generally distributed
but nonconfluent..

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

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*In the Sudan, exceptional specimens of A. marmoreum may have a scutal width of at least 1.3 greater than length (Figure 74), but in these, large punctations are scattered over the entire scutal surface.

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Figures 64 and 65, o, dorsal and ventral views, Sudan specimen Figures 66 and 67, q, dorsal and ventral views, Uganda specimen

AMBLYOMMA COHAERENS

Note: The illustrated is malformed in the following areas: left scutal margin anteriorly and right scutal margin laterally deformed, festoons on right side absent, only three legs on left side. Diagnostic criteria are not affected by these malformations.

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