Mebs, D., M. Yotsu-Yamashita & S.W. Toennes

Tetrodotoxin content of Rough-skinned Newts, Taricha granulosa (Salamandridae), from their northern distribution range, British Columbia, Canada, and Southeast-Alaska, USA. pp. 82-88.

Abstract. Rough-skinned Newts, Taricha granulosa, occur along the west coast of North America, reaching their most northern range limits in British Columbia (BC), Canada, and Southeast-Alaska (AK), USA. They contain one of the most potent neurotoxins, tetrodotoxin (TTX), which varies considerably in concentration between individuals and populations. Analysis of specimens from a coastal area of Prince Rupert (BC) were found to contain low TTX-levels and traces only of its analogue 6-epiTTX; the toxin was not detected in juveniles from the eastern ranges, Terrace (BC). Likewise, low values were detected in specimens from Revillagigedo Island (AK), whereas newts from a pond near Juneau (AK) exhibited about ten-times higher TTX-concentrations. While T. granulosa colonised the archipelago of Southeast-Alaska after the great ice age 10,000 years ago, newts have been introduced in certain areas, such as to Juneau from opposite Shelter Island in the 1960s. The high variation in toxicity raises the question of the toxin’s biogenetic origin, whether it is endogenously synthesised or sequestered from unknown external sources. Further studies on toxin levels in distant populations may provide some hints which local conditions may favour the occurrence of TTX in T. granulosa.

Key words. Amphibia, Urodela, Taricha granulosa, tetrodotoxin, British Columbia, Canada, Alaska, USA.