Fig. 1.

A: SEM of three adult female antennal flagellar annuli. Flagellum is turned slightly ventral. Bordering each side of the leading surface (L) are the dorsal (asterisk) and ventral (double asterisks) surfaces. The type-A trichoid sensilla are found in greatest abundance in a band along the distal (d with arrow) and proximal (p with arrow) margins of the leading, dorsal, and ventral surfaces of each annulus. arrowhead, styliform sensillum complex. B: SEM of three adult male antennal flagellar annuli. Leading surface (L) view showing the long, male-specific trichoid sensilla arranged as phalanxes, one pair on the distal (d with arrow) and proximal (p with arrow) margins of the dorsal (asterisk) surface and a similar arrangement of sensilla on the ventral (double asterisks) surface of each annulus. The pairs of phalanxes bend toward each other, forming an arch (a with line). A band of shorter trichoid sensilla located on the proximal margin of the leading surface connect the phalanxes, forming the scoop (s with line). Arrowhead, styliform sensillum complex. C: SEM showing the leading surface of a female flagellar annulus. Type-A trichoid sensilla (arrows) are found in greatest abundance along the distal (arrows) and proximal (arrows with asterisks) margins of the leading (view shown), dorsal, and ventral surfaces of each annulus. Along these margins, these sensilla are found in a band that is 2-3 sensilla deep and are the main sensillum type present. These bands merge toward the trailing surface and form a U-shaped cul-de-sac (not shown), similar but less conspicuous than the pattern of distribution of male-specific trichoid sensilla. D: SEM of a higher magnification of the leading surface of female flagellar annulus showing numerous sensillum types. Arrows, type-A coeloconic sensilla; arrows with asterisks, type-B basiconic sensilla; arrowheads, type-A basiconic sensilla; arrowheads with asterisks, type-A trichoid sensilla. Scale bars = 100 μm in A-C, 10 μm in D.