Antennal chemoreceptors of the desert burrowing cockroach, Arenivaga sp.

The antennae of Arenivaga have six types of chemoreceptor sensilla. Some of these have unusual morphological features which may be adaptations for survival in a dry habitat. The sensory dendrites are well protected by cuticular structures, and in some receptors stimulatory molecules must pass through long channels or through pores filled with strands to reach the sensory cells. Large grooved pegs (possibly pheromone receptors) are numerous on antennae of adult males, and grooved sensilla are described here in detail for the first time. Thin-walled pegs, present in males and females, do not have pore tubules or hollow filaments as observed in many other insects. Rather, they contain structures designated here as pore strands, since they have a dense core rather than a light center as previously described for pore tubules and filaments. These strands do not appear to be evaginations of the dendritic membrane, but are probably formed in association with the cuticular structures of the sensilla.