A POSSIBLE NEW SENSILLUM ON THE ANTENNAE OF ITOPLECTIS CONQUISITOR (HYMENOPTERA: ICHNEUMONIDAE)

Abstract

A sensillum in the shape of a truncate cylindrical peg is present on the apex of the antenna in both sexes of Itoplectis conquisitor (Say). The sensilla occur in distinct fields of 19 to 38 pegs per antenna in males , and 26 to 35 pegs per antenna in females (x = 30.6). The pegs measure 1 to 15 μ, in height in males and 4 to 13 μ in females, and 2 to 6 μ in diameter in males and 2 to 5 μ in females. Pegs in the inside ranks at the very tip of the antenna are shorter than those in outside ranks which are more subterminal in position. This height variation results in the flat to slightly concave tips of the pegs being aligned on approximately the same plane. Innervation was confirmed by light microscope observations of sectioned material. The placement of the pegs at the antennal apex suggests that they perceive stimuli in the act of antennal tapping.