To date, ten terpenoid alkaloids have been isolated from eight genera of millipedes, all within the subterclass Colobognatha-spare Siphonophorida that produces monoterpenes . The chemical diversity of the lecontii. This strong relationship between defensive gland secretion chemistry and phylogeny indicates that the millipedes are themselves producing the secretions de novo and suggests that the chemical diversity within the terpenoid alkaloids may arise from the evolution of cyclase genes.