No abstract

The skin of Bufo alvarius, a desert toad of Arizona, contains a number of indolealkylamines and their metabolites belonging to the common series of 5-hydroxyindolealkylamines and to the unusual series of 5-methoxyindolealkylamines. The most abundant representative of 5-hydroxyindolealkylamines is, as in numerous other toads, bufotenine (up to 3 mg per g dry skin), the most abundant representative of 5-methoxyindolealkylamines, O-methylbufotenine. In parotoid and coxal glands as much as 5-15 per cent of the dry weight is made up by this compound. Natural O-methylbufotenine has been isolated in a pure form and its identity with synthetic O-methylbufotenine definitely established. The B. alvarius skin presents three sulphur-containing indolealkylamines: one is bufoviridine, the well known O-sulphate of bufotenine, the other two are completely new compounds with sulphuric acid probably attached to the > NH group of the indole nucleus. All the hitherto described metabolites arising from the oxidative deamination of 5-hydroxyand 5-methoxy-indolealkylamines may be found in the B. alvarius skin: 5-hydroxytryptophol, 5-hydroxyindoleacetic acid, 5-methoxytryptophol and 5-methoxyindoleacetic acid. The occurrence of the above compounds points to the necessary presence in B. alvarius skin of a number of enzymes: tryptophan 5-hydroxylase, catalysing the forma tion of 5-hydroxytryptophan, aromatic L-aminoacid decarboxylase producing the de carboxylation of 5-hydroxytryptophan to 5-hydroxytryptamine, N-methyl transferase and 5-hydroxyindole-O-methyl transferase giving origin to the N-methyl and O-methylindolealkylamines, and finally sulphoconjugases catalysing the linkage of sulphuric acid to the 5-hydroxy group and the > NH group of the indole nucleus. The exceptionally rich sample card of indolealkylamines in the skin of B. alvarius seems of interest not only from the point of view of comparative biochemistry, but also from that of comparative enzymology and biochemical taxonomy.

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The Late Tertiary basaltic rocks of the Patagonian Meseta of Somuncura, Rio Negro, Argentina, extend for about 15,000 square km north of 42° South Latitude, approximately 60 miles from the Atlantic coast. It is a flat stepparian landscape of some 1200-1400 m elevation in which many temporary clay-lagoons are scattered. Small rocky streams filter from the basaltic up lands towards the lower slopes of the Meseta, about 700-500 m. The fauna of such an isolated en vironment is very peculiar and a high rate of endemic forms can be emphasized. Two new species of telmatobiid frogs are reported: Telmatobiusreverberii from the clay-lagoons of the stepparian uplands, and Telmatobius somuncurensis from the lower rocky streams. Adults and tadpoles of Telmatobius reverberii are described; this form has morphological and ecological affinities with the smaller Telmatobius praebasalticus of the volcanic lagoons of Neuquen, near the Southern Argen tine Cordilleras. Certain characteristics of Telmatobius somuncurensis are discussed, such as the uncommon everted cloaca and the similarity between the upper and lower rounded structures of its iris and the upper "meniscus" of the iris of the east-Brazilian Cydorhamphus. Probable biogeo graphic relationships and a tentative evolutionary history of these ancient leptodactylid stocks are discussed. * * *