RODENTS OF LIBYA 71 



from Libya are significantly larger, have less hair on the ears, are more 

 brightly colored dorsally (Buckthorn Brown as opposed to Snuff 

 Brown), have a greater suffusion of white ventrally, more orangish- 

 buff on the dorsal surfaces of the fore and hind feet, and have more 

 prominently bicolored tails. 



In M. m,ustersi the tail is markedly longer than the hind foot and 

 almost one fourth the length of the head and body, rather than only 

 slightly larger than the hind foot and one-fifth the length of the head 

 and body as in M. guentheri, and the sole of the hind foot is naked for a 

 greater distance posterior to the base of the toes. 



In the number of palmar and plantar pads and in the pattern and 

 number of the molar prisms and reentrant angles, the Libyan speci- 

 mens resemble M. guentheri and indicate relationship with the latter 

 species. 



Remarks. Hinton (1926) described M. mustersi as a species distinct 

 from Microtus philistinus Thomas of Palestine. According to Hinton, 

 M. mustersi is closely allied to M. philistinus, but differs in slightly 

 darker (less grayish) dorsal color, slightly narrower choanae, slightly 

 smaller auditory bullae, less reduction of the third molar posteriorly, 

 and less salient temporal ridges with a wider interval between them. 

 Hinton regarded these differences as somewhat tenuous but stated 

 that "craniologically" the specimens representing both Af. in ustersi and 

 M. philistinus, and upon which his comparisons are based, were all 

 subadult and that fully adult specimens probably would show more 

 marked differences. 



Ellerman and Morrison-Scott (1951) regarded M. mustersi and 

 M. philistinus as conspecific and relegated them both to subspecific 

 rank under M. guentheri. Toschi (1954) also considered M. mustersi 

 as a subspecies of M. guentheri. I agree with Ellerman and Toschi in 

 regarding M. mustersi as a member of the "M. guentheri" group but 

 feel that other morphological differences between the two are too 

 great to suggest conspecificity, and here M. mustersi is regarded as a 

 species distinct from M. guentheri. 



Hinton's description of Microtus mustersi from Cyrenaica in 1926 

 constituted the first record of occurrence of a microtine rodent for the 

 African continent, even though members of this group were widespread 

 throughout Europe and Asia. The type series of At. mustersi obtained 

 by Chaworth-Musters in 1926 from Barce, a specimen collected by 

 H. W. Setzer in 1955 from 10 kilometers southwest of rDl Faidia, and 

 the three specimens that I obtained from 5 kilometers west of Tocra 

 are all from Cyrenaica and constitute the only known representatives 

 of the subfamily Microtinae in Libya. 



