THERMOREGULATION IN 2 POPULATIONS OF THE MATABELELAND MOLE-RAT (CRYPTOMYS-HOTTENTOTUS-NIMRODI) AND REMARKS ON THE GENERAL THERMOREGULATORY TRENDS WITHIN THE GENUS CRYPTOMYS (RODENTIA, BATHYERGIDAE)

The social Matabeleland mole-rat Cryptomys hottentotus nimrodi occurs in both the high- and lowveld of Zimbabwe. The population in the highv eld has a mean (+/-S.D.) resting metabolic rate (RMR) when acclimated for three months in the laboratory of 0.83 +/- 0.04 cm(3) O-2 g(-1)h(- 1) (n = 12) within the thermoneutral zone (TNZ) of 31-32 degrees C. Th e body temperature (T-b) within the thermoneutral zone is low 34.4 +/- 0.08 (n = 12) and remains stable at ambient temperatures (T(a)s) from 25-32 degrees C. Above 32 degrees C, T-b increases albeit slightly to 36.6 +/- 1.46 degrees C (n = 12). The conductance is high 0.17 +/- 0. 02 cm(3) O-2 g(-1)h(-1) degrees C-1 (n = 24) at the lower limit of the rmoneutrality. The mean RMR in the TNZ. The population in the lowveld has a mean (+/-S.D.) resting metabolic rate (RMR) when acclimated for three months in the laboratory of 0.95 +/- 0.07 cm(3) O-2 g(-1)h(-1) ( n = 12) within the thermoneutral zone (TNZ) of 28-30 degrees C. The bo dy temperature within the thermoneutral zone is low 34.0 +/- 0.03 (n = 12) and remains stable at T(a)s from 25-30 degrees C. Above 23 degree s C, T-b increases, albeit slightly, to 37.8 +/- 1.14 degrees C (n = 1 2). The conductance is high 0.04 +/- 0.09 cm(3) O-2 g(-1)h(-1) degrees C-1 (n = 24) at the lower limit of thermoneutrality. The mean RMR at 18 degrees C (the lowest Ta tested) was 1.96 +/- 0.12 cm(3) O-2 g(-1)h (-1), which is 2.0 times that of the RMR in the TNZ. These thermoregul atory parameters are compared with published data on other species of Cryptomys from Southern and Central Africa.