Xanthine excretion in a desert scorpion,Paruroctonus mesaensis

Summary The nature of the nitrogen excretory products of a desert scorpion (Paruroctonus mesaensis) was investigated. Two dimensional thin-layer chromatography revealed one major component, comigrating with xanthine, and a minor component which occurred sporadically and comigrated with hypoxanthine. The identity of xanthine as the major nitrogenous waste was confirmed with additional chromatographic systems, by ultraviolet spectrophotometry, and by enzymatic analysis. P. measensis excretes over 90% of its waste nitrogen in the form of xanthine, and is the first animal shown to be primarily xanthotelic. Most other arachnids excrete primarily guanine. No guanine or uric acid was detected inP. mesaensis urine, although some uric acid, probably of dietary origin, was found in fecal material. Some possible mechanisms for, and consequences of, xanthine excretion are discussed.