Functional morphology of the fossula spongiosa in some reduviids (Insecta-Heteroptera-Reduviidae)

Abstract

Legs of Reduviidae show modifications and specialised structures adapted for their predatory habits and efficient prey capture. The variable forelegs of these insects apparently reflect the correlation between the structure of the legs and the types of prey. The tibial pads or fossula spongiosa are a common feature in the forelegs or fore- and midlegs of most of subfamilies of Reduviidae. The functional morphology of the tibial pads of the forelegs of three insects, Haematorrhophus nigroviolaceus (Reuter), Pirates affinis Serville and Triatoma rubrofasciata (De Geer) has been studied. The oily substance produced by the cushion-like secretory tissue and the minute tenet hairs on them increase the ability to sustain static tension and enhance the gripping efficiency of the legs. Scanning electron micrographs reveal distinct morphological variations among the tibial pads. In addition to the shape and size of the organs, the number, structure and density of the tenet hairs on them markedly vary. The ability of the foretibial pad to sustain static tension on smooth and rough surfaces has been found to differ among the insects studied and this is remarkable in predatory insects.