CHEMISTRY AND MORPHOLOGY OF THE TERGAL GLAND OF FREELIVING ADULT ALEOCHARINAE (COLEOPTERA, STAPHYLINIDAE) AND ITS PHYLOGENETIC SIGNIFICANCE

Morphology and chemistry of the tergal gland, an abdominal defensive g land of the Staphylinidae subfamily Aleocharinae, is studied comparati vely in twenty-two species of ten Central European tribes. To determin e trends in the morphological evolution of the tergal gland the result s are compared with well-known evolutionary trends of gland systems of other insects. The possible chemical evolution of the gland secretion is proposed by considering the biosynthesis of the different secretio n compounds and by testing their biological efficiency on Calliphora l arvae (irritancy, mortality). The morphological evolution probably pro ceeded from a small reservoir with only a few glandular cells D1 (prim itive) to a large and bilobed reservoir with a great number of glandul ar cells D1 (advanced). In the chemistry of the quinone-containing gla nd secretion, long-chain fatty acids as solvents in primitive species were probably replaced by short-chain fatty acids (derived condition). Most advanced species also use hydrocarbons and aldehydes as solvents . With reference to these results, both a statistical (Jaccard-coeffic ient) and a cladistic analysis are performed to test previous ideas on the phylogeny of the Aleocharinae.