Key to species of the subfamily Gerbillinae

1 Upper incisors with longitudinal groove (Figure 34A)......................................................... 2

- Upper incisors without longitudinal groove (Figure 34B)....................................... Psammomys obesus

2 Tail with a distinctive tuft extending about 1/2 to 2/3 of the tail.................................. Sekeetamys calurus

- Tail without a distinctive tuft extending about 1/2 to 2/3 of the tail............................................... 3

3 Large form, with skull length exceeding 30 mm .............................................................. 9

- Small form, with skull length not exceeding 30 mm .......................................................... 4

4 Soles of fore and hind feet predominantly naked............................................................. 5

- Soles of fore and hind feet predominantly hairy.............................................................. 7

5 Smaller species, HB less than 68 mm, greatest length of skull does not exceed 22.5 mm ................. Gerbillus henleyi

- Larger species, HB greater than 73 mm, greatest length of skull exceeds 26 mm .................................... 6

6 Hair bases on the tail rump gray, smaller tympanic bulla, posterior margin of mastoid chamber never extends to the level of supraoccipital bone........................................................................... G. dasyurus

- Hair bases on the tail rump white, well developed tympanic bulla, posterior margin of mastoid chamber exceeds the level of the supraoccipital bone.............................................................................. G. nanus

7 Coloration of the back is bright orange sandy buff, well developed tympanic bulla, posterior margin of mastoid chamber extends beyond the level of the supraoccipital bone................................................. G. cheesmani

- Dorsal coloration is bright yellowish sandy buff, tympanic bulla not well developed, posterior margin of mastoid chamber never exceeds supraoccipital bone........................................................................ 8

8 Ears pigmented, posterior end of the nasal bone truncate, anterior palatal foramin long while posterior foramina relatively short........................................................................................... G. andersoni

- Ears not pigmented, posterior end of the nasal bone rounded, anterior palatal foramin short while the posterior foramina rela- tively long................................................................................... G. gerbillus

9 Claws black............................................................................. Meriones libycus

- Claws not black....................................................................................... 2

10 Ears not pigmented....................................................................... Meriones crassus

- Ears pigmented......................................................................... Meriones tristrami