Proceedings of the United States National Museum

PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM issued \miVsJX, Q^W^ hy (he SMITHSONIAN INSTITUTION U. S. NATIONAL MUSEUM Vol. 106 Washington : 1956 No. 3377 MAMMALS OF THE ANGLO-EGYPTIAN SUDAN By Henry W. Setzer Introduction The discovery of factors of medical importance in mammals of the southern Anglo -Egyptian Sudan prompted this study of their taxon- omy, distribution, and zoogeography. The mammalian hosts obtained on a preliminary investigation in 1948 and subsequent studies in 1949-1950 form the basis of the present report. The material was obtamed by personnel of U. S. Naval Medical Research Unit Number Three, and it currently bears Chicago Natural History Museum catalog numbers. This collection is to be divided equally between the Chicago Museum and the United States National Aluseum. Thus, unless otherwise indicated, specimens from localities bearing no museum abbreviation in the "specimens examined" sections of the accounts of species are in the above collection. Specimens from localities such as Bor, Gondokoro, Khartoum, Lake No, and Mongalla, which bear no museum designation, are in the U. S. National Museum from previous African explorations. Locali- 1 This paper is based upon studies of the material collected by U. S. Naval Medical Research Unit Number Three. The author is a collaborator with this research group. 447 448 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe ties indicated by italics were either not to be found on any maps available, or would overlap locality dots on the distribution maps. Abbreviations designating other collections examined are: AMNH, American Museum of Natural History ; BM, British Museum (Natural History); and MC'Z. Museum of Comparative Zoology at Harvard College l^idess otherwise stated, all measurements are in millimeters and the capitalized color terms are from Ridgway, "Color Standards and Color Nomenclature," 1912. It will be noted that in some accounts total length is used and in others length of head and body. This has been dictated by the type of measurement recorded by the collector on the original label. No effort has been made to translate the total length into length of head and body and tail length, since it is probable that the two measurements would not be comparable. I would like to express my sincere thanks to the many individuals who have aided in the preparation of this report; especially to the members of the Mammal Room of the British Museum and to Dr. H. W. Parker, its head keeper who so kindly allowed me to incorporate specimen records and to describe new forms in the mammal collection; to Miss Barbara Lawrence of the Museum of Comparative Zoology at Harvard for the privilege of describmg new material in that collection; to Colin Campbell Sanborn and the officials of the Chicago Natural History Museum for making their Sudan collection available for study and for the privilege of describing new kinds; to the Office of Research, Medical Department, United Slates Navy, and to Naval Medical Research Unit Number Three, who made possible the collecting of the material and furnished transportation to England so that I might be able to study the material housed at the British Museum (Natural History) ; to the director of the United States National Museum and to mj^ associates in the division of mammals who have aided in many ways, to Mrs. Aime Awl, staff artist of the department of zoology who so kindlj" prepared the maps, and to Mrs. Helen Gaylord who has typed the manuscript through its many drafts. The Anglo-Egyptian Sudan lies roughly between 3° and 22° north latitude and between 23° and 37° east longitude. Its geographic boundaries encompass approximately 967,500 square miles of territory having quite diverse topography. Almost the entne northern half of the country is extreme desert, while the southern half is predominantly savanna interspersed with isolated mountain masses such as the Jebel Marra, the Nuba Mountains, Mount Baginzi, and the Imatong, Didinga, and Dongotona Mountains in the southeast. The most conspicuous topographic feature of the Sudan is the Nile River with its tributaries—the Atbara, the Blue Nile, the Sobat, and the White Nile, each with a complex drainage sj'stem. In general, the MAMMALS OF ANGLO-EGYPTIAN SUDAN—SETZER 449 mammals of the Sudan are not limited in their distribution by the Nile. This is particularly so in the White Nile drainage where vast areas of sudd occur. The formation of sudd dams across channels allows for free interchange of mammal populations from bank to bank in certain areas in the south. The extent to which the Nile serves as a barrier in its more northern reaches is not clearly demonstrable since collections from either bank are not known north of Khartoum. From the scanty evidence available, it does seem that the Nile serves as a barrier to certain kinds of mammals in the more northern reaches but to a less appreciable degree in the south. Africa has been divided into major biotic districts based on the distribution of plants and birds by Chapin (1932). Some of these districts, in the Sudan, do not seem to correspond to mammal distribution at any taxonomic level. The mammals of the Sudanese Arid District and the Sudanese Savanna District appear to be alike. Only the genus Galago seems to have a distribution that fits the general outlines of the Sudanese Savanna District, but this genus occurs also in areas that are referred to the Abyssinian Highland District. The geographic area assigned to the Ubangi-Uelle Savanna District appears to be too large, since no elements of this district have been found east of the Nile. The Abyssinian Higliland District does not appear to be represented in the Sudan to any degree. The only element which possibly could be assigned to this district is Praomys albipes, whose main range is in the highland area of Ethiopia. The Somali Arid District was thought by Chapin to include the northeastern portion of the Sudan (bounded by Eritrea and the Red Sea) and the portion in the extreme southeast. The former area is probably correctly included in the Somali Arid District since the maned rat Lophiomys and the small dik-dik Rhynchofragus are found there. No mammals characteristic of the Somali Arid District have been found in the southeastern area, which may be included more properly in the East African Highland District. Otherwse, the bounds assigned by Chapin to the East African Highland District in the Sudan are satis- factor}' from the point of view of mammalian distribution, since the affinities of most of the mammals of this area are with those of Kenya Colony and East Africa. In certain areas mammals do not conform as well to the biotic districts of Chapin as do birds. The mammalian fauna of the Sudan is rather homogeneous and the major portion of the country may be assigned to what I would call the Sudanese Ai'id Savanna District. The remaining parts of the sudan have mammalian faunas which show some affinity to faunas of the Somali Arid District, the Ubangi- Uelle Savanna District, and the East African Highland District. The area l3^ing along the Ethiopian border is somewhat distinct bo- 450 PROCEEDINGS OF THE NATIONAL MUSEUM tanically but its mammals are poorly known. On the basis of the scant data that is available it seems unlike!}'' that this area can be referred to the Abyssinian Highland District. Certain areas of endemism are demonstrable. Perhaps the most striking is the Jebel Marra in Darfur Province where a large propor- tion of the resident mammals have differentiated at least subspecifi- cally. Other places such as Mount Baginzi, the Nuba Mountains, and the Imatong Moimtains also show a rather high degree of endemism. The mammalian fauna of the last-named region (with its Figure 1, —Principal collecting localities in the Anglo-Egyptian Sudan. (Scale: 1 incli = 250 miles.) MAMMALS OF AXGLO-EGYPTIAN SUDAX—SETZER 451 companion ranges, the Dongotonas and the Didingas) has a close affinity with the East African fauna but shows a high degree of in situ development. These mountain ranges of the southeastern Sudan need much further field work in order to evaluate properly their zoogeographic status and the degree of isolation of their faunas from those of East Africa and from each other. Of the three, only the Imatong Range is adequately represented by specimens. It is in- teresting that the mammals showing the greatest differentiation are those whose normal habitat is in a forest envh-onment. In these mountains, the forest has become isolated from adjacent forested areas by large regions of arid savanna. This isolation is apparently the result of the dessication of central Africa after the last Pleistocene Pluvial period. Worthington (1937, p. 316) with regard to the great lakes of Africa and theu- fish faunas, saj^s: It is yet premature to date the earlier changes involved—the time at which the main rivers of Africa became set in their courses, the formation of the rift valle3's, the depression of the Lake Victoria basin, and the reversal of many of the rivers of Uganda. But the later changes, including the dessication of Lake Edward and probably of Lake Victoria can now be dated within reasonably certain limits by correlation with climatic change during the Pleistocene in other parts of Africa and with the glacial and inter-glacial periods in the northern hemi- sphere. The exact correlation of the individual pluvial and interpluvial periods is not yet fixed, but in general terms the climatic changes which were taking place soon after the beginning of the Pleistocene were responsible both for the glacia- tions in the north and the pluvials on the equator.

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