The moth Utetheisa galapagensis (Lepidoptera, Arctiidae) is an endemic of the Galápagos Islands. Unlike other species of Utetheisa, which are gaudily aposematic, it is uniformly grayish in appearance. Our initial presumption that U. galapagensis lacks the plant-derived systemic pyrrolizidine alkaloids that account for the aposematism of its congeners was erroneous. U. galapagensis feeds on species of Tournefortia (Boraginaceae), one of which, T. rufo-sericeae, was found to contain pyrrolizidine alkaloids (5% of dry weight). U. galapagensis of both sexes contain these compounds. The drabness of U. galapagensis may be attributable to the fact that the moth is nocturnal, unlike its aposematic congeners. Two additional species of Utetheisa from the Galápagos (U. devriesi, and U. perryi) are also non-aposematic. Whether the three Galápagos Utetheisa are primitively drab, or whether their cryptic condition is secondarily derived from an aposematic ancestry, remains unsettled.
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