HOSTS

The black rhinoceros, Diceros bicornis subspp., and the white, or square-lipped, rhinoceros, Ceratotherium simum subspp., are listed as hosts by all authors. The hosts of our Equatoria Province specimens listed above, if they were rhinoceros, represent both genera inasmuch as only the black rhinoceros occurs near Magwe east of the Nile and only the white rhinoceros occurs across from Nimile west of the Nile.

In Tanganyika each of several rhinoceros hosts of various ticks yielded small numbers of this species (J. B. Walker, unpublished).

King (1926) suspected, from the places in which he found specimens of this tick, that it may also attack the hippopotamus. Evans (1935) recorded domestic cattle and sheep as hosts in Tanga nyika. Lewis (1934) mentioned a domestic donkey in Kenya and De Meza (1918A) took specimens from domestic cattle in Nyasaland and from elephants in Tanganyika. Neumann (1907,1910B) listed an eland as host, and Mettam (1932) noted the jackal from Uganda.

BIOLOGY

Unstudied. Specimens are commonly reported from the hosts'

That the specific name rhinocerotis de Geer (1778), used by many authors for this species, actually applies to a distinct species in the genus Amblyomma was indicated by Dönitz (1910B).

Schulze (1932A) suggested that D. rhinocerinus be placed in the genus Amblyocentor on the basis of minor morphological pecu liarities. There is, however, little utility in fragmenting tick

genera on the basis of insignificant characters. Amblyocentor is therefore considered as a subgenus of Dermacentor.

A few male specimens have the anterior spots of the scutum partially or completely fused, thus resembling the female scutum. Neumann (1907,1910B) described the subspecies permaculatus on the basis of these differences. Subsequent investigators with the exception of Tonelli-Rondelli (1930A), have disregarded this name and considered these characters to be no more than individual variation (Bequaert 1930B).

A "provisional name", D. rhinocerotis arangis, was applied by Lewis (1934, p. 39) to specimens of variable color but after com parison with other specimens this name was withdrawn (footnote of same page).

Females have two large patches of reddish brown hairs and scattered lighter hairs near the posterior margin of the body dorsally. These, and the cuticle of this species, have been studied by Schulze (1944A) and Jakob (1924). Schulze (1941) noted features of the tarsus and haller's organ, and (1950A) of the dentition of this tick.

IDENTIFICATION

Key characters readily separate and identify the two Dermacen tor species discussed in this report.

HAEMAPHYSALIS

INTRODUCTION

Haemaphysalids are so small and inconspicuous, except when the females become greatly engorged, that they are seldom ade quately represented in collections. Collectors frequently overlook them when larger and more colorful ticks are present. Many species show a marked predilection for seldom examined hosts such as hyraxes, birds, and hedgehogs. Some haemaphysalids appear to be actually quite rare in nature.

In tropical and southern Africa, the genus Haemaphysalis is represented by the ubiquitous H. leachii subspp., chiefly a car. nivore parasite, and by approximately fifteen less common species. In the nearby Madagascan archipelago, among whose ten known endem ic tick species are nine haemaphysalids, most are distinctly related to the Oriental fauna. Asia has some fifty or more haemaphysalid species, which, in proportion to the total tick fauna, are to that continent what rhipicephalids are to Africa. A dozen forms are listed in the Russian fauna (Pomerantzev 1950). Of a total of eighteen ixodid species in the Philippines (Kohls 1950), not including the cosmopolitan kennel tick, one third are haema physalids. The Americas and Europe claim only about five species each.

Since Nuttall and Warburton's (1915) revision of this genus, the African haemaphysalid fauna has received but little attention from biologists, systematists, or collectors. Many records in cluded here represent considerable extensions of known range. Obviously, some few African species remain to be discovered and described. Differentiation of most African haemaphysalids is relatively easy, either by certain combinations of characters or by unique characters for individual species. Morphological characters and facies of most species are comparatively quite constant. An important exception is H. leachii subspp., among the African forms of which there is very considerable variation.

Haemaphysalids are usually three host parasites, although exceptions do occur. The life cycles of H. 1. leachii and of H. aciculifer have been fairly well studied In the laboratory, but

few reliable biological data are available for African species. Factors governing morphological and biological variations of H. leachii subspp. pose an especially intriguing problem.

Medically, the only African haemaphysalid of known importance is H. 1. leachii, a vector of boutonneuse fever (tick typhus) of man and of malignant jaundice of dogs. The same species may also be a reservoir of Q fever. The high potential of H. bequaerti as a medically important species has been recently suggested and others probably eventually will be incriminated in disease transmission of academic or practical interest.