Fine structure of antennal sensilla of the female sphinx moth, Manduca sexta (Lepidoptera : Sphingidae). II. Auriculate, coeloconic, and styliform complex sensilla

The antennal flagellum of the female sphinx moth, Manduca sexta, bears eigh t types of sensilla: two trichoid, two basiconic, one auriculate, two coelo conic, and one styliform complex. We previously described the fine structur e of the trichoid and basiconic sensilla (Shields and Hildebrand 1999). In this paper, we describe one type of auriculate, two types of coeloconic, an d one type of styliform complex sensilla. The auriculate (ear- or spoon-sha ped) sensillum is a small peg that averages 4 mu m in length,is innervated by two bipolar sensory cells, and has structural features characteristic of an insect olfactory sensillum. Each of the two types of coeloconic sensill a is a small peg that averages 2 mu m in length and is recessed in a cuticu lar pit. One type of coeloconic sensillum is innervated by five bipolar sen sory cells and has structural features characteristic of an insect olfactor y sensillum or olfactory-thermosensillum, while the other is innervated by three bipolar sensory cells and has structural features characteristic of a n insect thermo-hygrosensillum. The styliform complex sensillum is a large peg that averages 38-40 mu m in length and is formed by several contiguous sensilla, the number of which depends on the location of the peg on the fla gellum. Each unit of the styliform complex sensillum is innervated by three bipolar sensory cells and has structural features characteristic of a ther mo-hygrosensillum. We also ascertained the number and distribution of each of the eight types of sensilla on a single flagellomere (annulus) about mid way dong the flagellum of a female antenna. A total of 2216 sensilla were f ound on the dorsal, ventral, and leading surfaces of that annulus.