WEST AFRICA: NIGERIA (Pearse 1929). FRENCH WEST AFRICA (Neumann 1899,1901,1911. Rousselot 1951,1953B. Villiers 1955). GOLD COAST (Nuttall and Warburton 1911. Nuttall 1916. Stewart 1936).

CENTRAL AFRICA: FERNANDO PO (Schulze 1943A). CAMEROONS (Neumann 1899,1901,1911. Ziemann 1912A. Nuttall 1916. Jojot 1921. Rageau 1953. Schulze 1943A. Rageau 1951,1953. Dezest 1953. See HOSTS below). FRENCH EQUATORIAL AFRICA (Bequaert 1931 refers the type locality to French Equatorial Africa, not to Belgian Congo. Fiasson 1943B. Rousselot 1951,1953B). RIO MUNI (Nuttall 1916. Schulze 1943A). BELGIAN CONGO (See French Equa torial Africa above. Neumann 1899,1901,1911. Nuttall 1916. Nuttall and Warburton 1916. Schwetz 19270,1932. Schouteden 1927. Bequaert 1930A,B,1931. Schoenaers 1951A. Rousselot 1951,1953B. Theiler and Robinson 1954).

EAST AFRICA: SUDAN (King 1926. Hoogstraal 1954B).

ETHIOPIA (Nuttall 1916).

KENYA (Neave 1912. Nuttall 1916. Anderson 1924A. Lewis 1931A,B,C,1939A. See HOSTS below). UGANDA (Nuttall and Warbur ton 1911. Mettam 1932,1933. See HOSTS below). TANGANYIKA (Neumann 1899,1901,1907,1910B,1911. Morstatt 1913. Bequaert 1930. Reichenow 1941B. Schulze 1943A).

UNION

SOUTHERN AFRICA: SOUTHERN RHODESIA (Nuttall 1916). OF SOUTH AFRICA (Bedford 1929A,1932B. Cooley 1934. Cooley 1934. Some or all of this material refers actually to Ixodes pilosus: Arthur, correspondence.7

HOSTS

The range of hosts of adult Ixodes rasus includes a large variety of animals from mice and elephant shrews (small insectivores) to leopards, large antelopes, and domestic dogs. It is difficult to determine whether this tick displays predilection for any group of mammals. The picture for immature-stage host preferences is equally uncertain. Whether individual Whether individual "subspecies" have characteristic preferences differing from each other remains to be demonstrated.

Published reports of adults and immature stages found together on a single host are categorized below by associated stage and sex for what they may be worth in eventually answering questions of host preferences and biology of this species.

Stage or sex not specified: Domestic cattle from Uganda, leopard and domestic dog from Gold Coast (Nuttall and Warburton 1911). Domestic sheep from Kenya (Lewis 1931B).

Cricetomys emini (giant forest rat), Crocidura sp. (shrew), Crocidura manni, Hybomys univittatus (back-striped mouse), Leggada musculoides (pygmy mouse), Lemniscomys striatus (striped grass mouse), Rattus rattus (house rat), Taterillus gracilus angelus (gerbil), Thyronomys swinderianus (cane rat) (Pearse 1929, from Nigeria).

Buffalo, blue duiker, forest or red duiker, and domestic cattle (Mettam 1932, from Uganda). Black duiker (Villiers 1955, from Ivory Coast). Warthog (Ziemann 1912A, from Cameroons). Cane_rat (Schwetz 1927C, from Belgian Congo). Okapi (Schouteden 1927, from Belgian Congo). Impala (Bedford 1932B and Cooley 1934, from South Africa). Tree hyrax, Dendrohyrax (Schoenaers 1951A, from Belgian Congo).

Larvae alone: Common on small and large birds in Kenya (state ment should be checked for accuracy) (Lewis 1939A).

Nymphs alone: Bdeogale mongoose (Schulze 1943A, from Tanga nyika). Man (Nuttall 1916, from Ethiopia). "Antilope brune" (Bequaert 1931, from Belgian Congo).

Females with larvae: Okapi (Schwetz 1927, from Belgian

Congo).

Females with larvae and nymphs: Akeley's suni or dwarf antelope, Nesotragus moschatus akeleyi, (from Kenya; this female tick corresponds more closely to the description of Ixodes rasus cumulatimpunctatus than any other specimens that I have seen). Mole rat, Tachyoryctes sp. (HH legit at Njoro, Kenya).

Females with nymphs: Water chevrotain, giant elephant shrew, giant forest rat, wild pig, mongoose, and domestic dog (Schulze 19434, from Tanganyika and Cameroons). Hyrax (Procavia sp.) (Bedford 1929A, 1932B, from South Africa). "White mongoose" (specimens seen by HH, from Cameroons).

Females alone: Domestic dog (Schulze 1943A, from Tanganyika; Rageau 1951, from Cameroons; Nuttall 1916, from Gold Coast). Domestic cattle (Nuttall and Warburton 1911, from Uganda*). Domestic goat (Nuttall 1916, from Belgian Congo).

Tree hyrax, Dendrohyrax arboreus (Bequaert 1931, from Belgian Congo). Hyrax (?Procavia) (Schwetz 19270, from Belgian Congo). Giant forest rat (Cricetomys) (Schulze 1943A, from Rio Muni; others seen by HH, from Uganda). Grass rat (Arvicanthis abyssinicus nubilans) and groove-toothed rat (Otomys tropicalis elgonis) (specimens from the latter host closely correspond to description of Ixodes rasus cumulatimpunctatus (HH legit at Njoro, Kenya). Duiker (Bequaert 1930A, from Tanganyika). Serval from Kenya, pangolin and bush pigs from Cameroons (Nuttall 1916). Leopard (Nuttall et al 1911, from Cameroons*). Large gray mongoose (Herpestes caffer and slender mongoose (Myonax cauui (Bedford 1932B, from South Africa).

Females and males: "Man and domestic dog" (Nuttall et al, from Gold Coast). Hyrax (Neumann 1899, from French Equatorial Africa- not Belgian Congo according to Bequaert 1931); bush pig (Schulze 1943A, from Tanganyika); leopard (Nuttall 1916, from Southern Rhodesia; others seen by HH, from Kenya). Pangolin (Specimens seen by HH, from Uganda).

*Stages or sex not reported in literature cited, but determined from Nuttall collection in British Museum (Natural History).

BIOLOGY

After having collected numerous specimens of Ixodes rasus from many small mammals in Kenya, from sea level to 8000 feet elevation, it was surprising to find this species so rare in the Sudan. From Pearse's (1929) report on Nigerian ectoparasites, I. rasus appears to be common on small mammals there. The reasons for these considerable differences in local populations remain to be explained.

Nuttall (1911) categorized I. rasus in the biological group within the genus Ixodes in which males and females are usually found together on a host that either wanders or does not travel far and in the subgroup in which the sexes are often found in copula on the host. Present evidence partially supports the inclusion of Ixodes rasus in the last subgroup and careful col lecting may subsequently prove that this species should be so considered.

Systematic search probably will show Ixodes rasus to be a common tick in many parts of tropical Africa. Examination of rodents in certain areas should prove fruitful. Seeking for every tick on a variety of animals will undoubtedly reveal a few, small inconspicuous, well-hidden Ixodes ticks along with more apparent, more numerous, larger, and more colorful ticks of other genera.

Questions concerning the biology of Ixodes rasus in its various forms (i.e. subspecies) offer a challenge in one of the most fascinating zoological areas of the world.

DISEASE RELATIONS

Unstudied.

REMARKS

Schulze (1941) noted certain features of the haller's organ of I. rasus (cf. also K. W. Neumann 1943). A comparison of this

organ with that of other Ixodes species is presented in table form by Arthur (1956B).

Remarks on morphology of this species are contained in papers by K. W. Neumann. These have not yet been seen and complete references are not available except for: (1942) Z. Morph. Okol. Tiere, 38(2):358, 362. (Morphology of subcoxa of subspecies cumulatim punctatus); and (1945) Zool. Jb. (Anat.), 69(2):286, fig. 8. Jakob (1924B) included this species in his review of the relationship of tick genera from the standpoint of comparative morphology.

Both sexes are readily distinguished by their completely closed, usually circular anal grooves, an easily observed character in all specimens except some greatly engorged females in which the anal area is depressed and the associated grooves are difficult to dis cern. Only one other African species, Ixodes ugandanus Neumann, 1906 (with which Ixodes ampullaceus Warburton, 1933, from Uganda is quite possibly synonymous), is known to have closed anal grooves; these are not circular but characteristically oval and unite in a slight posterior elongation. I. ugandanus has not yet been found in the Sudan.

Schulze (1943A) indicated that circular anal grooves are characteristic of this species but that some specimens in which these grooves are expanded to a broad oval outline are merely atypical individuals of the same species. According to Schulze, the anal grooves of I. rasus may even be narrowed posteriorly.

Schulze (19434) differentiated three subspecies of I. rasus and one "related species" as follows:

I. rasus rasus: Short, broad palpi and hypostome; retrograde auriculae (lateral spurs of ventral basis capituli); pro nounced single punctations on scutum. (From Cameroons).

I. rasus cumulatimpunctatus: Long, narrow palpi and hypostome; perpendicular auriculae; and small scutal punctations, some of which appear to be formed of a small group of smaller, contiguous punctations. (Tanganyika to Fernando Po).

I. rasus eidmanni: The same characters as given above for I. rasus rasus, but "more strongly chitinized and darker", and