The most conspicuous feature of the spiracle of Ornithodoros moubata is the so-called cribriform plate. This is a massive crescent-shaped vesicle consisting of three layers; the underlying sclerotized endocuticle, a series of branching pillars or pedicels arising from this basal layer and a very thin outer membrane, supported on the distal ends of the pillars and enclosing the whole structure (Fig. 1 A). The cavity lying between the basal cuticle and the outer membrane and ramifying between the pillars is continuous with the atrium of the spiracle.
