Gross morphology of the central nervous system of a phytoseiid mite

The general morphology of the central nervous system is analysed in intact females of the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae), using a nucleic acid label (YOYO-1) and confocal laser scanning microscopy. The somata of all cells that comprise the synganglion reside in the cortex. The cortex harbours an estimated total of 10,000 cells. The somata are densely packed in the cortex and cells residing in the inner cortex may only occupy about 1.8 μm. As in all Arachnida, the synganglion is divided in a sub- and a supra-oesophageal nervous mass. Both the cortex and the neuropil appear continuous between these two nervous masses. The sub-oesophageal nervous mass mainly consists of the four paired pedal ganglia that are each associated with a leg. The prominent olfactory lobes are ventrally associated with the first pedal ganglia. A small opisthosomal ganglion occupies the most caudal part of the sub-oesophageal ganglion. The rostral part of the supra-oesophageal nervous mass consists of the paired cheliceral and palpal ganglia. The supra-oesophageal ganglion is the largest ganglion in the supra-oesophageal nervous mass and unlike all other ganglia it is not associated with any of the major nerves. It is therefore more likely involved in secondary information processing.