Water, Nitrogen and Ion Balance in the African Treefrog Chiromantis petersi Boulenger (Anura: Rhacophoridae), With Comments on the Structure of the Integument

<p> Physiological and anatomical investigations were carried out on <em> Chiromantis petersi </em> , an African rhacophorid treefrog, with the following results:</p><p> 1. The minimum rate of evaporative water loss (EWL) was 0.41&plusmn;0.25 mg/g.h.</p><p> 2. The maximum rate of water uptake in dehydrated frogs averaged 75% body weight/h in the first 10 min of rehydration.</p><p> 3. The low EWL correlates with the unique structure of the chromatophore units of the dorsum, the sides and the gular region.</p><p> 4. The high rates of water uptake correlate with the structure of the verrucae hydrophilica of the abdominal and femoral surfaces. These verrucae are not unique to this species.</p><p> 5. When denied water and force-fed mealworms for 30 days, plasma osmotic concentrations increased from 210 mosM to 384 mosM, with Na+, Cl&minus; and urea contributing most to the increase.</p><p> 6. The ratio of urinary K+&ratio;Na+ excretion is 3&ratio;1.</p><p> 7. Excretion totaled 155 mg N/kg&middot;day with 97% as uric acid, 2% as ammonia and 1% as urea.</p><p> 8. Since urea accumulated in the body at the rate of 58.5&plusmn;6.1 mg N/kg&middot;day, total nitrogen production was 213 mg N/kg&middot;day. Uric acid formed 70% thereof.</p><p> 9. <em> Chiromantis petersi </em> is capable of surviving without free water for prolonged periods and is as well adapted to its xeric environment as are many desert reptiles.</p>