Published online by Cambridge University Press: 06 April 2009
The external structure of the capitulum of all stages of Dermacentor parumapertus is described in detail. The capitulum is divisible into an extra-basis and basis regions. The former consists of a dorsally grooved hypostome or food channel overlapped by a labral membrane, along its whole length. The salivary channel lies above the labral membrane, being bordered laterally by the meso-ventral margins of the outer cheliceral sheaths. Within the basis a vertical wall separates the base of the palpal cavity from the rest of the basis. This wall is produced backwards to form a wing or ala on either side of the pharynx and to it are attached dilator and constrictor muscles. Opening of the fore-part of the pharynx, i.e. where it is in the form of a V-shaped depression overlapped by a wedge, is effected by ventral and ventro-lateral dilator muscles, and closure by the elasticity of the pharyngeal walls.
The pharynx, oesophagus and salivary glands are described.