Nuttalliella namaqua (Ixodoidea: Nuttalliellidae): Spiracle structure and surface morphology
The structure and surface morphology of the femaleNuttalliella namaqua spiracle are described with the aid of light and scanning electron microscopes. The spiracle, located posterolaterad to coxa IV, consists of a convex fenestrated plate lacking the marginal peritrime of ixodids, and a small, concave macula with a crescentic ostium enclosed by a lip. Ramifying pedicels around interpedicellular spaces are easily observed through the wide surface fenestrae. Below the ostium, a subostial space leads to a wide atrial chamber from which tracheal trunks extend. A thick-walled valvelike projection guarding the connection between the subostial space and atrial chamber probably controls air passage aided by the valve and atrial muscle action. Nuttalliellid spiracles have structural properties of both Ixodidae and Argasidae. However, the fenestrated plates are unique and differ significantly from the plates of Ixodidae and Argasidae.