idiosomal

Idiosomal is an adjective used primarily in acarology and arthropod anatomy to describe structures associated with the idiosoma, the principal posterior body region of mites and ticks. The gnathosoma (capitulum) bears the mouthparts and is considered distinct from the idiosoma.

Anatomically, the idiosoma houses most internal organs, including portions of the digestive, reproductive, and excretory systems, and is the region from which the legs emerge. In many species, the idiosoma is covered by a rigid dorsal shield and ventral plates that form the characteristic idiosomal integument.

In taxonomic descriptions, idiosomal is used to specify location or relation to this region, for example idiosomal plates, idiosomal chaetotaxy, or idiosomal glands. The term helps distinguish features from those of the gnathosoma.

These terms are used across acarology and in broader arthropod anatomy, though idiosomal features are most commonly discussed in mites and ticks. The word derives from Greek idios, meaning "own or distinct," and soma, meaning "body."