Structure and chemistry of the Dufour gland in Pristomyrmex ants (Hymenoptera, Formicidae)

All individuals of the three species of Pristomyrmex studied have a Dufour gland with a conspicuous hammer-shaped distal part, that is connected to a thin-walled proximal reservoir through a very narrow stalk. The secretory d istal part is formed by high columnar cells that are characterized by a hig hly folded apical wall. The lateral cell junctions apically correspond with the crenel tops, which gives individual cells a peculiar shape with a deep apical depression. The cytoplasm of the secretary cells contains a very we ll developed smooth endoplasmic reticulum and Golgi apparatus, numerous mit ochondria and lysosomes. Histochemical analysis indicates a positive reacti on for the presence of a lipid secretion in the hammer-like part. Gas chrom atographic analysis of glands of P. pungens workers reveals the secretion t o de formed of a mixture of simple volatile monoterpene hydrocarbons; alpha -pinene, beta-pinene, limonene and camphene. Similar, but species character istic mixtures of four monoterpenes were found in Pristomyrmex: brevispinos us and Pristomyrmex sp.1. Behavioural experiments did not allow a conclusiv e determination of the function of the gland.