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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 amblyommas is the A. marmoreum group, in which the range of species variation 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 # 8. ### 5f 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 Wervent (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. # has been found naturally infected 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transmitters of veterinary diseases, cause damage to animal skins, or debilitate animals through the volume of blood withdrawn or by initiating wounds that develop into ugly secondary sores.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 antelopes 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 annually. KEY TO SUDAN SPECIES OF AMBLYOMMA MALES

l. Lateral grooves extending anteriorly at least to middle of scutum. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -2

Lateral grooves absent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -7

2. Eyes small, hemispherical, situated in a well defined depression (i.e. orbited)...................3

Eyes flat or very slightly convex, not in a depression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

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

Figures "68 and 69

Festoons only dark colored. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

4.

5.

7.

Scutum with numerous coarse punctations,

and with a red lateral spot. (Rare in

Sudan)...........................................A. POMPOSUM
Figures 80 and TBI

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

Figures 92 and 93

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

Figures E. and 65

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 7.5 mm. Dark scutal
areas more widely separated by pale
areas than in A. marmoreum (see Figures).........A. NUTTALLI

Figures 75 and 77

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.
muttalli........................................A. MARMOREUM

Figures 72-ETE

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

Figures 33 and 39

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

Figures ETERT35

1.

3.

4.

FEMALES

Eyes in a well-defined depression
(i.e. orbited), hemispherical or
strongly convex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Eyes not in a depression, flat or
slightly convex. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -4

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)...........................A. POMPOSUM

Figures 32 and T33

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. . . . . . . . . . . . . .A. LEPIDUM

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

Figures 5:-55

Scutum with central and lateral areas
largely pale colored; punctations either
large Or fine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Scutum with either central or lateral
areas largely dark colored; punctations

only fine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 5.

7.

Scutum with some large punctations
scattered over entire surface;
length usually equalling or greater

than width:#. Eyes flat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Scutum with few large punctations
only on anterior half; wider than
long, mostly pale (reddish brown).
Eyes slightly convex. (Very large
tick, chiefly from rhinoceros)...............A. RHINCCERCTIS

Figures

Scutum with extensive pale median

area that is broadly rounded poste

riorly. (Large tick, chiefly from

tortoise).......................................A. MARMOREUM Figures

Scutum with less extensive pale median
area that narrows to a point poste-
riorly. (Medium size tick, chiefly
from tortoise and leguan lizards)................A. NUTALLI
Figures 7

Scutum dark centrally, small pale spot
on posterior border, lateral fields
with small pale spots or entirely
dark. Eyes flat. Very narrow pale
rings on legs. (Chiefly from elephant)..........A. THOLLONI
Figures 9

Scutum pale centrally, lateral fields
with only small pale spots. Eyes
slightly convex. Broad pale rings
on legs. (Chiefly from buffalo)................A. COHAERENS

Figures

*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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