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Mouthparts are situated close to the anterior margin of the body. The hypostome formula is 2/2 to 2.5/2.5, the apex is notched and bears a corona of three or four rows of small denticles in four to six files.

The larval and nymphal illustrations and descriptions of A. vespertilionis by Neumann (1896) are quite good, though they shall have to be expanded for present day purposes. These have been employed subsequently by the same author, Nuttall et al (1908), Bedford (1934), and others.

ARGAS SP.

(Not illustrated)

A single damaged larva, mounted on a slide, sent by Mr. E. T. M. Reid of the Sudan Veterinary Service, represents an un known species of tick. Although many of the characters of this specimen are obliterated, enough are preserved to indicate dis tinct differences from A. vespertilionis, to which it is probably more or less closely allied, and from all other described species. This larva was collected from a Pachyotus bat at Latome, Equatoria Province, on 18 March 1951 by Mr. J. Owen.

ORNI THODOROS*

INTRODUCTION

Both important African species of Ornithodoros, 0. moubata and 0. savignyi, occur in certain areas of the Sudan, where they are known as haim (). From two to five other species indubitably exist in the Sudan but have not yet been found there. Approximately fifty species comprise the genus throughout the world. 0. moubata is the most important tick vector of relapsing fever in Africa and its bite is often painful. O. savignyi has been sus pected to be a relapsing fever vector, although incriminating evi dence in nature is negative or unconvincing.

Ornithodoros ticks are thick, leathery, and podlike. They may be more or less difficult to find but pain when they bite signifies their presence. In contrast to Argas ticks, which usually parasitize birds and bats, most Ornithodoros ticks parasitize mammals, including bats, and only exceptionally attack birds, reptiles and amphibians.

The two species under consideration represent a somewhat more advanced stage in evolution of parasitism than do Argas and other Ornithodoros species in that their larvae remain in the large, leathery egg until ready to make the larval nymphal molt. The safety of the tough egg capsule affords delicate larvae considerable protection from the elements. 0. moubata and 0. savignyi are un usual in this respect; larvae of most other Ornithodoros species are active and feed from animal hosts. Shortly after hatching larvae molt to nymphs that soon set out to find a host. Nymphs and adults feed rapidly, in a matter of a few minutes to an hour or two, and are seldom transported while feeding on the host. fore, usually found only in their resting places.

They are, there
Ornithodoros

*Some writers replace the os ending used here by us. The original name used by Koch (1844) was spelled with an os ending, and this is generally though not universally conceded to conform to the rules of nomenclature and of philology. This question has been reviewed by Najera (1951).

ticks are able to withstand long periods of starvation and are very resistant to aridity. The two species discussed in the following pages have been widely spread along man's trade routes.

Subgenera of Ornithodoros are scarcely better established than those of Argas. 0. moubata and 0. savignyi are closely related species with only one other kindred kind, O. eremicus Cooley and Kohls, 1941, of Utah, western North America. Some workers would include only these three species in the genus Ornithodoros and all others in several different genera. This position seems an unnatural approach and a useless complexity. For present purposes, 0. moubata and O. savignyi are treated as in the subgenus Ornithodoros, the only one presently known to be represented in the Sudan.

In addition to these two tampans, it is certain that several other species of Ornithodoros occur in the Sudan and await dis covery. Among these should be 0. foleyi, 0. delanoei subsp., and possibly some member of the 0. Tholozani group. When more inten sive search is undertaken in the Sudan it will probably be found that O. erraticus is localized but widely distributed here. 0. erraticus is broadly characterized by small size (maximum length 7.5 mm., usual length 3.0 to 5.0 mm.), oval shape, closely crowded hemispherical granulations interspersed by large discs, and absence of tarsal armature and of cheeks surrounding the mouthparts. Specimens will probably be found in small mammal burrows.

The following are the other known Ornithodoros species that occur in Africa, with selected references concerning them:

O. arenicolous Hoogstraal, 1953 (C); description of all stages; biology; from rodent, hedgehog, and Varanus lizard burrows in Egyptian deserts. Absence of spirochetes (Davis and Hoogstraal 1954).

0. capensis Neumann, 1901; described from penguin inhabited islands off Cape Province. Found on Cargados Carajos Island in Indian Ocean (Neumann 1907). Challenger Expedition specimens from St. Paul's Rocks (Nuttall et al 1908). Present on islands off Southwest Africa (Tromsdorff 1914). Biology of hosts and description of habitat, St. Croix Island off Cape Province (Hewitt 1920). Other South African records (Bedford 1934).

Records from western Australia (Taylor and Murray 1946). Present on marine birds, Guam (Kohls 1953). Specimen from leg of soldier on island in Lake Nyasa (Hoogstraal 1954C).

0. coniceps (Canestrini, 1890); described from Venice, Italy. Specimens, from near Aral Sea, in St. Petersburg Museum (Birula 1895); these quoted by Yakimov and Kohl-Yakimov (1911) and Yakimov (1917,1922). Present in France (Guitel 1918, Theodor 1932, Roman and Nalin 1948). As 0. talaje from Fezzan, Morocco; introduced with pigeons; severe se quelae in human victims (Martial and Senevet 1921). From bats and pigeons, life cycle, Tunis (Colas-Belcour 1929D). Description of all stages, Palestine (Theodor 1932). Biology, Palestine (Bodenheimer 1934). Present in Spain (Gil Collado 1947,1948A,B). Present in Morocco (Blanc and Maurice 1950). Present in Nablus area of Jordan; parasite of chickens and persons; infected with spirochetes (Badu dieri 1954,1955). Transmits fowl spirochetes ("Brumpt's Precis"). Life cycle (Davis and Mavros 1956C).

0. delanoei delanoei Roubaud and Colas-Belcour, 1931; described from porcupine burrow, Morocco. Biology (Roubaud and ColasBelcour 1936). Life cycle and larval feeding (Colas Belcour 1941). Non transmission of spirochetes (Colas Belcour and Vervent 1949). Present in Egypt (Hoogstraal 1953C). Ab sence of spirochetes (Davis and Hoogstraal 1954). Life cycle (Davis and Mavros 1956A). Biological observations and dis tribution in Egypt; descriptions of immature stages (Hoogstraal 1955E).

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0. delanoei acinus Whittick, 1938; described from cave in British Somaliland. Haemoglobin (Wigglesworth 1943). Biology (Robinson 1946). Coxal organs ("glands"") (Lees 1946B). Trans piration from cuticle (Lees 1948). Egg waxing organ (Lees and Beament 1948). Weight of tick and of its cuticle, fed and unfed (Lees 1952). Larval and nymphal measurements, and the increase in size following each molt and male meas. urements have been noted by Campana Rouget (1954).

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