42 U.S. NATIONAL MUSEUM BULLETIN 275 



that in Ctenodactylus, the isolated population has not yet attained 

 full species status. 



Ctenodactylus gundi vali represents a population that originally 

 became isolated from a population of C. g. gundi and has since con- 

 tinued to evolve independently in the more inland areas of Libya. 

 As far as is known, the range of C. g. gundi in Libya is limited to 

 rocky escarpments of the Gebel Nefusa and that of C. g. vali to 

 larger wadis and occasional rocky outcroppings of the steppe region 

 of northeastern Tripolitania. Both subspecies are clearly allopatric, 

 and it is doubtful that the two forms would interbreed if they were 

 to make contact. Morphological differences between the two popula- 

 tions are more on the level of subspecific distinctness. For the present, 

 it seems best to regard Ctenodactylus gundi vali as an incipient species 

 closely approaching full species status. 



The dormice of Libya, by virtue of their apparent rarity and 

 disjunct distribution, present a distributional pattern differing 

 markedly from that of other Libyan rodents and demonstrate clearly 

 the effects of geographic isolation on evolutionary processes. 



The three subspecies of the Libyan dormouse, Eliomys quercinus, 

 are geographically, morphologically, and ecologically distinct and 

 illustrate the modern concept of the biologically defined polytypic 

 species. In the past, the subspecies E. q. tunetae and E. q. cyrenaicus 

 have at one time or another been regarded as full species by taxonom- 

 ists. Until very recently the genus Eliomys was considered to repre- 

 sent a polytypic genus composed of several distinct species distributed 

 in Europe {Eliomys quercinus), North Africa {Eliomys munbyanus 

 and Eliomys lerotinus), and the Middle East {Eliomys melanurus). 

 These various isolated, morphologically distinct "species," in addition 

 to a new subspecies, Eliomys quercinus denticulatus from the Fezzan, 

 are now regarded as subspecies of a single polytypic species, Eliomys 

 quercinus. 



The discontinuous distribution of these subspecies of E. quercinus 

 is suggestive of a pattern expected for full allopatric species. In most 

 cases, these allopatric subspecies show an amount of morphological 

 distinctness typical of sympatric species. Because species normally 

 consist of a series of continuous or discontinuous local populations 

 and each population is composed of individuals with a different 

 genetic constitution, a polytypic species would be expected to contain 

 individual populations differing in phenotypic expressions. The 

 morphological dissimilarity among the various "allopatric subspecies" 

 of E. quercinus is not suggestive of specific differences but expresses, 

 instead, a highly variable species gene pool. The ranges of Eliomys 

 quercinus tunetae and Eliomys quercinus cyrenaicus include the Gebel 

 Nefusa and the Cyrenaican Plateau respectively, while Eliomys 



