denticles of hypostome with a small apical "hook", proximity of sensory organs in the integument, and absence of a definite "peripheral zone" of the integument. (Rio Muni, or Spanish Guinea).

I. vanidicus:

Similar to I. rasus but with anal grooves horseshoe shaped or circular but not closed posteriorly. (Tanga nyika to Cameroons).

IDENTIFICATION

Males are characterized by circular anal grooves (see REMARKS above), narrow marginal fold beside the scutum, fairly many to numerous fine scutal punctations, and short palpi with segments 2 and 3 of about equal length. This reddish brown species is about 2.8 mm. long and 1.8 mm. wide and has a broadly rounded posterior margin. The tarsi are usually humped but in some specimens which otherwise conform to this description they are tapering.

Females also have closed anal grooves. Their scutal puncta tions are similar to those of males. The hypostome and palpi are long and narrow and the basis capituli ventrally has a large spur (auricula) arising from each lateral margin. The tarsi are either tapering or somewhat humped.

Note: As presently considered, any African Ixodes male or female with circular, closed anal grooves is I. rasus. Within the large amount of material seen in various collections there is considerable variation in most other characters, the significance of which await to be determined by Dr. Arthur.

Figures 226 and 227, o, dorsal and ventral views Figures 228 and 229, q, dorsal and ventral views

PLATE LXV

- 557

Lotti Forest is at 4500 feet elevation. This is the only record of this species from the Sudan. About a dozen monkeys of the same species examined in Lotti Forest and at other places at different altitudes in the same forest were free of ticks. An equal number of monkeys, Cercopithecus mitis stuhlmanni, from Lotti Forest were tickless, as were numerous specimens of other monkeys (Setzer 1956) examined elsewhere in the Sudan.

DISTRIBUTION

I. schillingsi, a parasite of East African Colobus monkeys, does not appear to range outside of wooded savannah and forested areas. It is the sole described African representative of a complex of species occurring in Asia, Madagascar, Australia, and Europe.

EAST AFRICA: SUDAN (Hoogstraal 1953E,1954B. Arthur, s.).

KENYA (Nuttall 1916. Lumsden 1955. Arthur, ms. See HOSTS below). TANGANYIKA (Neumann 1901,19070,1910B,1911. Nuttall and Warburton 1911. Morstatt 1913. Arthur, ms.). ZANZIBAR (Arthur, ms.).

SOUTHERN AFRICA: MOZAMBIQUE (Neumann 1919A, 1911. Nuttall

and Warburton 1911. Santos Dias 1953B).

HOSTS

Man is parasitized by I. s. schillingsi according to a single record for a female tick of this species from Njoro, Kenya (Lumsden

1955). Aside from this, Colobus monkeys, also known as guereza or leaf-eating monkeys, are the only known hosts. As stated below, all other records from different mammals, including man and monkeys other than Colobus refer to undescribed Ixodes species or subspecies.

Colobus polykomos caudatus (Neumann 1901,19070,1910B. Nuttall and Warburton 1911). C. polykomos dodingae (Sudan record above). Colobus sp. (Nuttall 1916).

Anderson (1924B) recorded Rattus rattus kijabius as a host in Kenya. Specimens of this tick species collected by Anderson in Kenya, now in British Museum (Natural History) collections, are labelled as from Colobus monkeys and others bear no host data (Arthur, ms.). The rodent host is believed to be an error.

Lewis (1931C) listed this tick from a duiker, bushbuck, and domestic cattle in Kenya. These four collections, two from bush bucks and one each from the other hosts have been examined at British Museum (Natural History) and found to refer to an entirely different species. They were then referred to Dr. Arthur, who considers them to be an undescribed subspecies of Ixodes pilosus (Arthur, ms.).

Rageau (1953B) reported specimens from man and from another kind of monkey, Cercopithecus (= Lasiopyga) cephus cephus. These represent an undescribed species related to Ixodes schillingsi (Arthur, ms.).

BIOLOGY

This species is a parasite of Colobus monkeys and uncommonly of man. It is said to prefer young hosts and attaches exclusively to the eye according to collecting notes furnished Neumann (1901). Females have been taken from around the eyes and ears and in the axillae of adult Colobus monkeys in Kenya and on the eyelid of a Colobus monkey in the Sudan.

The male has been found only in copula on the host (and once alone on a tree trunk) and its feeding habits are not known. Larvae, nymphs and both sexes of adults may occur on the same host (Arthur, ms.).

Extremely few ticks of any genus attack primates as hosts of predilection (Hoogstraal 1953E). Ixodes schillingsi appears to be one of these few.

Monkeys, lemurs, and other primates usually groom themselves and each other so meticulously that external parasites have little chance of surviving on them. Certain exceptions should, however, be noted. When wishing to examine baboons for ectoparasites, one should choose large, lone males who wander separate from the group. Individual baboon hobos have yielded as many as 350 ticks (Rhipicephalus simus simus) while others living in groups in the same areas have been free of ticks or have been infested by only one or two specimens. The striking rarity with which one observes easilyvisible groups of Colobus monkeys grooming each other immediately suggests that because this practice is so infrequently indulged, I. schillingsi has managed to survive on this genus of monkeys but not among others.

REMARKS

The close relation of Ixodes schillingsi to Ixodes lunatus Neumann, 1907, a Madagascan parasite of rodents that also infests insectivores (Hoogstraal 1953E), has been described by ColasBelcour and Grenier (1942) who consider that these two ticks might be regarded as related subspecies. The features of the haller's organ of I. schillingsi are listed in a table by Arthur (1956B).

IDENTIFICATION

Males are easily recognized among the African Ixodes fauna by the following characters: Anal grooves racket shaped (ante riorly slightly wider than "horseshoe shaped"), not closed. Legs normal length, but fourth pair comparatively long, coxae with first three pairs bearing a small internal spur posteriorly, coxa IV with a small external spur. Scutum with one lateral fold, convex, with many large, subequal punctations. Basis capituli with a sharp, pointed posteromedian spur ventrally. Measures about 2.3 mm. long and 1.4 mm. wide.