A Taxonomic Revision of the African Snake Genus Dasypeltis (Reptilia: Serpentes)

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Language: English

From the introduction:

"The snakes of the genus Dasypeltis have long been the object of special attention, attention due primarily to their exclusive egg diet, and the related adaptations of skull and vertebral column. While engaged in a study of these adaptations, I was faced with the problem of determining whether certain observed morphological variability was of racial significance. Unfortunately, none of the sprevious revisions of the genus permitted satisfactory assignment of all specimens, primarily because analysis had been restricted to material from particular expeditions, institutions or regions.

Mr. Arthur Loveridge had previously (1942) publishied his desire to extend his provisional classification, based on East African specimens alone, by the examination of material from other parts of Africa. Because of our overlapping interest this study was initiated as a joint project. It had been assumed, somewhat naively, that it would only be necessary to extend the coverage and to include the variation of the single species recognized by Loveridge over its entire range. Examination of specimens from other United States museums and analysis of data brought back by Loveridge from the British Museum soon forced some drastic changes in these assumptions. The hypothesis that but a single polytypic species was involved broke down and it became apparent that only the examination of a much more extensive series of specimens might offer some hope of defining the forms. Since Loveridge was anxious to complete several problems of greater interest to himself prior to his pending retirement, he withdrew from the present study after turning over his accumulated notes. The attack on the problem was then planned to included the examination of the largest practical number of specimens over the whole range of the genus.

It was at this time that Dr. M. Poll offered and I gladly accepted the opportunity to examine the magnificent collection of specimens in the Musée Royal du Congo Belge. The 306 specimens from this Institution comprised more than one quarter and almost one third of the total number of examples finally amassed from some eighteen different museums. These proportions only begin to give an impression of the value of the collection and I am grateful indeed to the Musée Royal du Congo Belge of Tervuren, both for the generous and extended loan of so much valuable material and for their publication of this lengthy study.

Besides the immediate need for a satisfactory classification, there was another reason why this study had a special interest. This was that the genus Dasypeltis appeared to form a particularly favorable subject for a detailed analysis of patterns of variation. Not only is it distributed over the entire Continental Ethiopian region, including the southwestern tip of Arabia, but the number of available specimens with good data appeared sufficient for at least a preliminary attack on the problem.

The scope of the revision was thus established as an analysis of the patterns of variation within the genus: determination first of the valid species, and second, description of geographic and individual variation as far as practicable. In view of the fact that the number of specimens firom many regions still leaves something to be desired, the accent has consciously been placed on a description rather than a nomenclatorial recognition of infraspecific variation. The taxonomic conclusions have been kept as conservative as possible, and it has been considered preferable to err in the direction of recognizing too few rather than too many forms. Larger series of specimens, material from additional l-ocalities and considerable field observation will probably be required before many of the remaining problems can be solved.

The format of this paper has hence been designed to be as useful as possible to future students. Some special methods of presentation and a particularly comrplete tabuliation of the data have been incorpovrated to permit its use as a foundation for a more detailed and geographically restricted analysis by workers in isolated regions with perhaps less than adequate library and / or exchange facilities. Consequently, not only the conclusions and the steps of the analysis leading to these, but the original specimen records as well have been listed. Those for a given region may then be re-examined as desired after new material has been obtained. Bibliographic citations in synonymy have also been presented in a manner designed to obviate the need for a re-examination of much irrelevant literature, and to facilitate reference to especially pertinent items."

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