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Figure 10, o, genital area
Figure 11, d, greatly engorged, lateral view (sketch)
Figure 12, , slightly engorged, lateral view

KEY MORPHOLOGICAL CHARACTERS, FAMILY ARGAS IDAE

Ornithodoros savignyi (Egyptian specimens)

PLATE VI

ARGAS

INTRODUCTION

Six Argas species occur in the Sudan. Four or possibly five other rare kinds have been recorded elsewhere in Africa. All the Sudan species may bite man, and, except possibly for the bat para sites, all may cause more or less painful sequelae. Insofar as our present knowledge goes, Argas ticks are rarely known to trans. mit human disease. Birds and bats are the chief hosts of most Argas species. The more widely spread species that parasitize domestic fowls are often serious pests and important vectors of avian diseases. The bat-infesting species also range rather widely and may possibly disseminate pathogenic organisms among their hosts.

Larval Argas ticks, in contrast to the two well known African argasids, Ornithodoros moubata and O. savignyi, are all active, suck blood, and often may be observed feeding on their hosts. Argas nymphs and adults, like those of Ornithodoros, are usually found only by careful searching in niches and concealed resting places in the immediate habitat of their favorite host.

Ticks of the genus Argas, unless recently engorged, are usual. ly flatter in profile than Ornithodoros, and can in most instances be easily distinguished from them by the presence of some morphological differentiation of the peripheral integument of the body.

Argas ticks are still surprisingly poorly known in most parts of the world and considerably larger collections, more data on their life history, and more exact collecting data are necessary before the biology and systematics of this genus can be finally settled.

The other species of Argas known to occur in Africa, some of which undoubtedly will be found in the Sudan, are the following: A. aequalis (Neumann, 1901) from Tanganyika. The host is unknown

and apparently only the original collection is known. Original. ly described in the genus Ornithodoros but subsequently referred to Argas (Neumann 1908B).

A. hermanni (Audouin, 1827) from Egypt. Neumann (1896) noted material

from Ethiopia and Hoogstraal (1952A) from bird nests in Egypt. We are still studying material referable to this species in view of its possibly unsatisfactory taxonomic criteria and species status.

striatus Bedford (1932A, 1934) from weaver bird nests, Cape Prov

ince, South Africa. This species is said to be closely related to A. aequalis, but both are in need of comparative biological

and morphological studies. A. transgariepinus (White, 1846) from South Africa. A. kochi (Neu

mann, 1901) from Basutoland possibly is a synonym. Berlese
(1913) reported specimens biting a child and walking on the
wall of a bank in Italy. Hoogstraal (1952A) described biology
in Egyptian bat caves. Hoogstraal (19540 ) noted presence in
Spain. A report on a study of the life cycle, biology, and
morphology of each stage will be presented in a forthcoming
paper.

Subgeneric classifications are not included for other groups in this work because their status is still moot. The issue has been forced in the genus Argas by the necessity for deciding whether to refer to some species generically as Carios, Ogadenus, or Argas. Studies on this subject are presently under way and will be reported more fully elsewhere.

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Figures 13 and 14, 2, Hypothetical Argas species

KEY MORPHOLOGICAL CHARACTERS, GENUS ARGAS

PLATE XII

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