الفهرس 
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Abstract
Oribatid mites (Arachnida - Acarina) play an important role for maintaining the fertility of the soil. Many terrestrial species can live successfully in different microhabitats, specially in mosses, fallen leaves, humus and rotten wood , so they have no difficulties to find a corresponding environment for their living with all abiotic and biotic attributes that they need. Also, these animals provide the soil with organic matter rich with nitrogen. Some investigators proved that some species prefer certain type of fallen tree leaves, so one can cultivate these plants in order to reclimate the agricultural soils. Others advocated that oribatids burrow long branching channels in the superficial layers of the soil. Also, undoubtedly many of the free-living mites directly and indirectly affect soil formation, plant productivity and litter decomposition by their vertical translocation of organic matter and dispersal of decomposer microorganisms. However , it is difficult to define or to determine the systematic position of many species due to the controversy that are found in scientific literature of oribatid mites taxonomy. In Egypt, recent years have seen a remarkable re-awakening of interest about oribatid mites taxonomy and 130 species are described till now , however these animals need thorough study in view of recent parameters of taxonomy. To solve this problem, and because the present is the age of computer, the present study discusses the applicability of numerical taxonomy on Egyptian oribatid mites in the study of the relationships among them and to compare between the numerical taxonomic method and the orthodox method to clarify the confused classification of species under the same family. Numerical taxonomy may be defined as ”the numerical evaluation of the affinity or similarity between taxonomic units and the ordering of these units into taxa on the basis of their affinities”. So, the taxonomic relationships are to be evaluated purely on the basis of resemblance existing in the material at hand. It must be substantial that the role of the computer in numerical taxonomy is not to replace systematists but to leave them free time for the collection of new data for computer and the evaluation of the results of the computations. Manifestly, numerical taxonomy has still a long way to go and will have to appeal to a larger number of zoologists than at present. It would seem that mites is an eminently suitable group in which one can examine the usefulness of numerical techniques. A reasonable number of characters of taxonomic value are available and a high proportion of these can be dealt with on a quantitative and qualitative basis. The authors believe that numerical taxonomy on oribatid mites will present a classificatory nightmare to the traditional worker, Examination of the specimens for identification was achieved through the temporary preparation. Numerical taxonomy begins by choosing the important characters that should not be less than sixty and from many parts of the animal body. The characters fall into three categories : viz.; presence / absence characters; qualitative and quantitative characters. Each character is given a code number. Then, standardization of characters is conducted to pool the information from different characters at a comparable scale. Moreover, the similarity coefficient (distance coefficient) is used through rigorous statistical methods. Finally, clustering of species takes place according to similarity values in the form of dendrograms (tree-like structure) that explain the relationships between species.