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laid from 100 to 427 eggs, averaging 219. Other individuals that had fed four times laid five egg batches totalling about 900 eggs over a thirteen month period (Patton and Cragg 1913). The embryonic development, described by Christophers (1906), is essentially like that of o. moubata.

Larvae, like those of 0. moubata, are nonmotile and do not feed. Although some undergo ecaysis in the egg, most larvae free themselves from the eggshell before molting to nymphs (@unliffe 1922). After splitting the eggshell, larvae molt to nymphs in five hours Davis 1947) to ten hours (Patton and Cragg 1913).

Four nymphal instars over a period of about 84 days and seven nymphal feedings were observed by Patton and Cragg (1913). Cun liffe (1922), on the other hand, noted that males appeared after four to six molts and females usually after the sixth' moltRea sons for differences in mumber of instars among argasids remain to be ascertained.

The very active nymphs commence feeding two or three days after molting and require fifteen to thirty minutes to reach repletionAdults normally feed for similar periods but the presence of both stages along remote camel trails would indicate that on occasion some tampans may remain longer on the host.

Females in Cunliffe's (1922) studies lived between 292 and 420 days at 30°C, and for an average of 775 days at 220C.

Spermatophores superficially similar to those of 0. moubata are utilized by this species (in Egypt), although Christophers (1906) and Nuttall and Merriman (1911) questioned their presence.

Other details of the life cycle have been reported by the above mentioned observers and by Rousselot (1953B). However, extensive and refined studies are still necessary.

Ecology

0. savignyi, among the tick species studied by Lees (1947), shows the greatest ability to limit water loss at high temperatures, The critical level for this species is 75°C. while for 0. moubata

it is 63°C. Even xerophilic hyalommas abruptly increase water loss at 45oC. (cf. page 154). This factor explains in part how the eyed tampan can exist in deserts where little other life is sustained. Cunliffe's (1922) studies, from which he concluded that the temperature and humidity requirements of both these tampans are much the same, should be repeated with special atoo tention to extreme levels.

Famous for the viciousness of its attack, this tampan is usually well known wherever it occurs. Natives quickly lead one to infested animal corrals, trees under which man and beasts rest, and well sides where the eyed tampan is superficially burrowed awaiting its prey. In Somaliland, Lipparoni (1951) reported, 0. savignyi is common under trees where soldiers tether their mules and o. moubata infests huts beside these trees. Although the adventitious presence of 0. savignyi in buildings must be expected, early records from human habitations appear to be based on misidentification. For instance, Drake_Brockman's various reports of 0. savignyi in British Somaliland buildings have been questioned by Anderson (1947). Anderson found 0. savignyi excom clusively outdoors in the same area, and 0. moubata, previously thought to be nonexistant in the area, exceedingly common in huts and coffee houses.

We have never observed 0. savignyi in sites directly exposed to the sun. Indeed, at the Khartoum quarantine one may see a long, seething line of thousands of hungry tampans helplessly confined to the shade of a row of acacia trees. A few yards away, separated only by the hot, nine o'clock sun, newly arrived cattle tied to a post fence tempt the tampans to cross the glaring strip. The next morning, in the coolness of seven o'clock, those tampans under the trees are all blood bloated and resting comfortably in the sand, others are dragging back from their hosts across the now nonexistant barrier, and the legs of the cattle are beaded with yet other podshaped ticks taking their fill of blood in a regular line just above the hoof.

Laboratory rats and mice, as noted by Heisch (1950A), assail this tampan. Rats feast on nymphs and adults. Mice commonly assault nymphs, but only particularly bold mice attack adults. These rodents, in turn, facilely escape bloodthirsty but lumber. ing adults, although small, active nymphs more easily attack them. Predators in nature do not appear to have been reported.

REMARKS

Christophers' (1906) extensive study on morphology and diges tion of 0. savignyi has been reviewed in the section on 0. moubata, which also contains a number of other data pertaining to both species.

The nymphal instars may be approximately determined according to Cunliffe's (1922) data, also presented by Campana Rouget (1954).

The haller's organ of 0. savignyi has been described and it lustrated (Schulze 1942).

Jakob (1924) used this tampan to illustrate certain theories separating the ixodids from the argasids on the basis of differences in external grooves, ridges, and prominences. He did not believe, as a result of these studies, that Argas developed from Ornithodoros, but rather that both genera had a common origin in the Uropodidae, a member of which, Discopoma africana Vitzhum, was illustrated.

DISEASE RELATIONS

MAN. The bite of 0. savignyi may have severely painful seque lae but this tampan has never been found infected with pathogenic organisms in nature, and transmission of pathogens has not been demonstrated until recently. Even the earlier assertions that the eyed tampan transmits human relapsing fever (Borrelia spp.) have been cast into considerable doubt by subsequent research.

DOMESTIC ANIMAIS. Camels and cattle suffer greatly and may even be killed by the volume of blood lost to numbers of eyed tampans in their pens,

EXPERIMENTAL. Leishmania donovani, which causes kala azar in human beings, does not develop in 0. savignyi. Trypanosoma cruzi undergoes development in this tick in the laboratory. T. evansi cannot be transmitted from the tick to animals except by inocula tion of a suspension of infected ticks.

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Experiments on transmission of heartwater (Rickettsia ruminan tium) of cattle by means of 0. savignyi-have been unsuccessful.

West Nile virus remains viable for at least three months in 0. savignyi, and transmission of the virus to mice by the bite of parenterally-infected ticks has been demonstrated. Similarly, specimens experimentally infected with Sindbis virus transmit the organism when biting.

Spirochetosis of chickens (Borrella anserina) is not trans mitted by this tampan,

IDENTIFICATION

See remarks under 0. moubata, pages 189 and 190.

FAMILY TXODIDAE

INTRODUCTION

All tick genera, save those in the family Argasidae and Nuttalliella, in the family Nuttalliellidae*, fall into the family Ixodidae and are referred to as whard ticksha or nixodidsia. The use of the term ixodid is not confined to the genus Ixodes. In Sudani Arabic, hard ticks are called "guradi (

. جاد

All ixodid genera that normally inhabit Africa also occur in the Sudan with the exception of Rhipicentor**. This genus is represented by R. gladiger (Neumann, 1908) bicornis Nuttall and Warburton, 1908) in neighboring Belgian Congo (Bequaert 1931) and further south in Africa. R. nuttalli Cooper and Robinson, 1908, occurs on various animals in South Africa and in Southwest Africa.

*The family Nuttalliellidae (Schulze 1935) contains only a single, exceedingly rare species, Nuttalliella namaqua Bedford, 1931(A), described from Little Namaqualand, Southwest Africa. This family appears to be a "missing link. A scutal outline is present but not structurally differentiated from the leathery, papillated inte gument. Though the mouthparts are anterior as in Ixodidae, the palpal segments are movable as in Argasidae, but an inner groove on the second segment is suggestive of the reduction in Ixodidae, in which the terminal segment is essentially merely a small ap pendage of the penultimate segment. The biology of this strange species is unknown.

**Rhipicephalus (Pterygodes) fulvus Neumann, 1913, a remarkable aberrant parasite of Northwest Africa, is frequently treated as a monotypic genus and sometimes as a subgenus of Rhipicephalus. See Neumann (1923) for description of male and Colas Belcour (1932) for description of female, nymph, larva, hosts, biology, and disease relations.

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