Fine structure of the coniform sensillar complex on the antennal flagellum of the stonefly nymph Paragnetina media (Plecoptera: Perlidae)

Abstract

Four to seven coniform sensillar complexes, each formed by 16–21 narrow spines, project perpendicularly from the distal end of middle and distal antennal flagellar segments of the stonefly nymph Paragnetina media. Each spine in the complex is innervated by two neurons with unbranched dendrites. The dendrites extend to a pear-shaped cavity in the tip of the spine. The tip of the spine is porous and contains channels filled with an amorphous material. Each pair of neurons is surrounded by three accessory cells. Based on structural similarities with the terminal multiporous sensilla of other insects, each spine in a sensillar complex represents a fundamental type of chemosensillum.