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DERMACEN TOR

INTRODUCTION

Dermacentor, a medically important genus in many parts of the world, is represented by only three species in tropical Africa. Small populations of two of these, D. c. circumguttatus and D. rhinocerinus, occur in Equatoria and Bahr El Ghazal Provinces of the Sudan. In Africa they are always rather rare and largely con fined to the rhinoceros and elephant. As such, they are of little more than academic interest. The identity of these species may be determined easily from the following keys and illustrations.

The third African species, D. hippopotamensis (Denny, 1843) (Ixodes bimaculatum Denny, 1843, and Amblyomma hippopotami Koch, 1844), was originally described from Hippopotamus amphibius of South Africa. Schulze (1919) erected the genus Cosmiomma for this species on the basis of its Hyalomma like characters although it lacks accessory shields and subanal shields. Zumpt (1951) sank Cosmiomma under Dermacentor but Theiler states (correspondence) that Schulze's definition justifies its retention as a genus. Other authors have placed it in Hyalomma. Still another study by a qualified student on the original material appears necessary be fore an acceptable systematic niche can be found for D. (C.) hippopotamensis.

D. (C.) hippopotamensis has been reported from South Africa and between "Zanzibar (i.e. East Africa) and the Great Lakes (Tan ganyika). For over a century, the only positively known specimens have been the types described by Denny and by Koch, which have been seen again by later students. In the collections of the East Afri can Veterinary Organization there is a single male taken from vegetation at Manyani, Teita District, Kenya, 5 November 1951, D. L. W. Sheldrick legit. This specimen, according to J. B. Walker (correspondence), is almost exactly like the type material illustrated by Dönitz (1910B). One or two specimens are in the collection of the Veterinary Department at Kabete, Kenya.

D. (C.) hippopotamensis is a large, brightly colored Amblyomma like tick. The male scutum is described as pale straw-yellow with symmetrical black markings and a few small punctations; ventrally

the legs are a deep liver-red. The female scutum is lightly punctate, largely pale in color with two submedian longitudinal black stripes and a pair of vertical black stripes near the posterior margin. The dorsal surface of the female posterior of the scutum is dull crimson with two large nearly circular, slightly elevated orange spots near the lateral margin. The apex and lateral mar gin of the palpi are dull crimson. The last tarsal segment and ventral surfaces of the legs are colored as in the male. This all but extinct beast should not be difficult to recognize.

Another species, D. niveus Neumann, 1897, parasitizes wild boars in Tunisia, Algeria, and Spanish Morocco (Senevet, ColasBelcour, and Gil Collado 1933), and various other animals in Eu rope and Asia.

It is difficult to determine what "D. reticulatus Neumann, listed by Stella (1938A,1939A,1940) from Ethiopia and by Niro (1935) from Somaliland, actually is. D. reticulatus, which does not appear to be a synonym of D. marginatus Sulz., 1776, as stated by Schulze (1933C), inhabits Europe and Asia. If its range does extend into the Ethiopian mountains, it would represent a unique ixodid distributional pattern, but conceivable on the basis of geographic distribution of other invertebrates.

Although it has not been our policy to discuss non-Sudanese species, the above remarks and a few additional taxonomic notes are inserted inasmuch as no review of the genus Dermacentor in Africa is available. Extra Sudan species have not been demons trated to be of medical importance and will not be included in subsequent volumes of this undertaking.

In various papers on Dermacentor, Schulze has divided the genus into several genera that show interrelationships within a closely circumscribed group and can, by contemporary concepts, be considered at most only as subgenera. These are of only slight interest in Africa, especially as the moot subject of subgenera will be further revised in future studies. D. circumguttatus was placed in the subgenus Puncticentor, which was subsequently synonymized (Zumpt 1951) under the subgenus Amblyocentor, in which D. rhinocerinus had been placed. The usefulness of the latter cate gory is questionable in the absence of study of the entire genus. These same remarks are possibly pertinent to the subgenus Cosmiomma, originally proposed as a full genus embracing only D. hippopotamensis.

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Figures 120 and 121, ♂, dorsal and ventral views Figures 122 and 123, q, dorsal and ventral views

DERMACENTOR C. CIRCUMGUTTATUS

Uganda Specimens

Loaned by British Museum (Natural History)

PLATE XXXVIII

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British Museum (Natural History) specimens, collected by Captain C. H. Stigand in the early 1900's, are the only ones extant from the Sudan (Hoogstraal 1954B,C). This is the most

northern and eastern record for the occurrence of the rare West African elephant dermacentor. It is unlikely to be found else where in the Sudan other than on the west bank of Equatoria Province and possibly in Bahr El Ghazal Province.

DISTRIBUTION

D. c. circumguttatus, a Central and West African elephant parasite, extends into East Africa only so far as the western parts of Uganda and the Sudan. In Mozambique, a separate subspecies is tentatively recognized on the basis of somewhat larger size and more irregular spotting.

WEST AFRICA: LIBERIA LIBERIA (Bequaert 1930A). SIERRA LEONE (Simp son 1913). IVORY COAST (Rousselot 1951,1953B).

CENTRAL AFRICA: CAMEROONS (Neumann 1901. Ziemann 1905. Rageau 1951,1953A,B). FRENCH EQUATORIAL AFRICA (Neumann 1897. Tonelli Rondelli 1930A. Rousselot 1951,1953B. Rageau 1953B). BELGIAN CONGO (Neumann 1897. Nuttall and Warburton 1916. Schwetz 1927A,B,C. Schouteden 1929. Bequaert 1930A,B,1931. TonelliRondelli 1930A. Rodhain 1936. Fain 1949. Schoenaers 1951A. Theiler and Robinson 1954).

NOTE: According to Theiler (correspondence), the record for Ruanda Urundi by Santos Dias (1954D) is incorrect.

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