remains quiescent for 28 days between terminating feeding and com mencing oviposition. Eggs hatch after 36 days; larvae and nymphs each feed for eight days. Twenty-four days after feeding, nymphs molt to adults. (See also Tselishcheva 1953).

The ecology and distribution of H. turanicum (= H. glabrum) in southern Africa are described by Theiler (1956). It is present only in the Karroo areas of the eastern Cape, western and south western Cape, the Cape midlands, and the Brokenveld of southern Orange Free State, but absent elsewhere in the Union and in Basu toland, Namaqualand, Bushmanland, Bechuanaland, and Southwest Africa. Although this tick exists in areas with as little as 0.5 inches of annual rainfall, it is more common where five to ten inches of rain falls annually. It is absent in areas with over fifteen inches of annual rainfall, in winter rainfall areas, and, with a single exception, where rain is distributed throughout the year. South African cold and heat do not appear to restrict the range of H. turanicum inasmuch as it is found in areas with up to 150 days of frost per year. This is the only Hyalomma in localities where snow occurs in South Africa. Karroo type vegeta tion areas including those mixed with Mesembrianthemum, sourveld grass, and, to a lesser extent, sweetveld grass support H. turaniIt is absent in all forests, parklands, grasslands, and other desert thorn, succulent, and grass areas. Adults are active during the summer and in some localities during the entire year.

cum.

Pervomaisky (1949) unsuccessfully attempted the rearing of a full F1 generation from parthenogenetic females of H. turanicum.

Neitz (1954) was unable to achieve transmission of the virus of sweating sickness of cattle in South Africa by means of H. turanicum (H. rufipes glabrum). As already noted, Delpy (1952) indicated that this tick is not of considerable importance in transmission of bovine theileriasis, Theileria annulata, in Iran.

The vertical rings of the leg segments of both sexes of H. turanicum are usually not so contrasty as they are in H. rufipes but the middle segments of the two pairs of hind legs show a dorsal enamelling not found in H. rufipes; this is especially distinct in dry specimens. The circumspiracular area of neither

sex is pilose and the scutal punctations are not so dense as in
H. rufipes, except in the scapular area. There is some variation
In density of scutal punctations and both sexes may resemble ex-
ceptionally heavily punctate individuals of H. marginatum; leg
characters, however, readily distinguish them. The scutum is
usually more leathery and not so black as in H. rufipes. The
female genital aperture, although unusually variable, is much
like that of H. marginatum (page 478) and considerably different
from that of H. rufipes. The various outlines of the genital
apron in available material are illustrated in Figure 207 A to

H.

These notes are made from material reared and presented by Dr. G. Theiler and from a small number of field collected specimens from Iran. A more extensive comparative study of larger amounts of reared and field collected specimens is indicated.

Theiler's laboratory rearings show the specific entity of this species. Consideration of H. turanicum as more closely related to H. marginatum than to H. rufipes appears justified.

Figures 208 and 209, o, dorsal and ventral views Figures 210 and 211, o, dorsal and ventral views

A, Q, genital area.

PLATE LX

- 533

HY ALOMMA ?SPECIES

(Figures 208 to 211)

The exact status of this form is uncertain. Since first mentioned from French Somaliland (Hoogstraal 1953D), a small amount of additional material, all from camels in the Somali biotope, from British Somaliland and Gebel Elba of southeastern Egypt, has been seen. An attempt will be made to obtain living material for rearing studies in order to define the morphological characters and taxonomic position of this form, both sexes of which resemble extreme variations among other species. The consistency with which males and females of this form are found together throughout coastal eastern Africa north of the equator arouses suspicion that this is a distinct genetic entity.

The male subanal shields lie directly posterior of the cen tral axis of the adanal shields; the scutum has characters in common both with heavily punctate H. marginatum and H. impeltatum. The female scutum is also similar to that of both of these species but the genital apron is like that of H. dromedarii although more depressed posteriorly. The outline of this apron in the specimen illustrated (Figure 211) represents the maximum width of this structure observed among available material; in other specimens it is more narrowly and elongately triangular, as in H. drome darii. The apron is not flanked by two lobes as in H. impeltatum, and its profile differs greatly from that of H. impeltatum.

IXODES

INTRODUCTION

Ixodes ticks are highly specialized in their habits. They frequently parasitize small or seldom examined hosts and are so small themselves that they are easily overlooked. Of some twentyfive species in Africa, six occur in the Sudan. Only sixteen specimens of the whole genus have been collected in the Sudan, all but three of these by the writer. This paucity of material is in striking contrast to Kenya, Cameroons, and Nigeria, where careful collecting is fairly productive for several species.

Phylogenetically, Ixodes ticks occupy a solitary position as a unique, highly specialized branch from proixodoidea stock. Sev eral exceptional morphological characters may be seen easily by comparison of Ixodes illustrations with those of other genera. The absence of eyes in this genus is believed by some to be a primitive character and the sexual dimorphism of the mouthparts is unparalleled in other ixodid ticks.

Intraspecific variation in the African Ixodes fauna is still poorly understood because only small amounts of material from many localities are available and probably also because these variations do not conform to those typically expected in ticks. Dr. D. R. Arthur of King's College, University of London, is presently undertaking an exhaustive study of this subject.

Biologically, ticks of this genus offer a wide field for research; their habits differ from all others. To elucidate this, Nuttall (1911A) erected the following biological criteria for

Ixodes ticks:

I. Species in which both male and female occur on the host.

(a) Species in which the sexes are found in copula
on the host (usually on wandering hosts).

(b) Species in which the sexes are found near each
other on the host (on either wandering or fixed
habitat hosts).