Femoral and tibial glands in the ant genus Strumigenys (Hymenoptera, Formicidae)

The distal part of the femur and tibia of the the six legs of workers, queens and males of five of the sis Strumigenys species examined is characterized by a dorsally occurring epithelial gland. In S. rogeri, we could find this gland only on the medleg femur and on the hindleg femur and tibia of queens, whereas it appears absent in workers. The glandular area is externally visible as an apparently smooth oval patch with numerous minute pores with a diameter around 100 nm. Both the femoral and tibial glands are formed by a considerable thickening of the tegumental epidermis in a region where the overlaying cuticle is reduced to approximately half the thickness it has elsewhere. The glandular epithelium is formed by secretory cells with basally located rounded nuclei and with an irregular microvillar differentiation of the apical cell membrane. Their cytoplasm contains numerous secretory vesicles of variable size and electron density, and scattered free ribosomes. The function of these hitherto unknown leg glands so far remains unknown.