| Abstract: | The fine structure of the digitiform sensilla on the distal segment of the maxillar palps of Tenebrio and Dermestes is described. Each sensillum is associated with a single sensory cell and three enveloping cells, which enclose two receptor lymph cavities. The inner receptor lymph cavity of both species shows a different structural feature. Branches of the outer dendritic segments, which contain numerous microtubules, run to the tip of the hairshaft. A dendritic sheath extends to the apex of the peg. The hairshaft possesses a second canal, which is free of dendrites. The poreless hairshaft is inserted in a cuticular canal; the longer distal part of the shaft is positioned in a narrow superficial groove. The digitiform sensilla do not show the typical structures of mechanosensitive sensilla. The absence of pores in the setal wall does not point to a function as olfactory or gustatory hairs. The presumed function of the sensilla is discussed in relation to thermo-, hygro- and CO2-receptors. |
