Taxonomy
View of the underside of the gnathosoma, comprising the structures involved in feeding © P York
Size
The average adult body length of Cheyletus eruditus (not including the mouthparts) is approximately 500 micrometres (0.5mm) for the female (range: 440 - 630 micrometres).
The homeomorphic male is smaller, with a range of 280 - 320 micrometres.
The heteromorphic form is about 400 micrometres long.
Morphology
In life, Cheyletus eruditus is translucent white to pale yellow. The body is widest between legs II-III and tapers slightly posteriorly.
The gnathosoma - which comprises the structures involved in feeding - is large, conspicuous and positioned on the anterior edge of the body.
The legs are all slender.
There are 2 stigmata - openings of the respiratory system - located next to each other in the middle of the dorsal surface of the stylophore - the fused bases of the chelicerae.
A segmented peritreme runs from each stigma. All the legs end in an ambulacrum - the structure on which the mite walks.
Each ambulacrum comprises two hooked claws flanking an empodium that has long, fine, T-shaped spines (tenent hairs) along its ventral surface.
The anterior position of the peritremes and stigmata and the presence of an empodium place C. eruditus in the order Prostigmata (= Actinedida). The character states that identify it as a member of the family Cheyletidae are the presence of a claw on the palp tibia (forming a thumb-claw process with the tarsus) and a large gnathosoma that joins the body anteriorly (rather than in the more usual slightly anteroventral position).
The two comb-like setae and two smooth curved setae on the palp tarsus are diagnostic of the genus Cheyletus.
Toolbox
Glossary
Sclerotized sclerotization the process of hardening, and often darkening, of the cuticle
Parthenogenetic parthenogensis a form of asexual reproduction whereby females produce offspring without being fertilized by a male mate.
Ambulacrum the terminal structure of the legs on which mites walk.
Peritreme gutter-like or tubular structure associated with a stigma
Empodium the part of the ambulacrum located between the claws of the leg tarsi in most mites of the order Prostigmata
Protegmen the area in front of the peritremes in mites of the family Cheyletidae
Gnathosoma body section comprising the structures involved in feeding
Chelicerae pair of appendages used to chew, pierce or suck food
Propodosomal relating to the propodosoma, the part of the body over the first two leg pairs
Hysterosomal relating to the hysterosoma, the part of the body behind the junction of the second and third leg pairs
Palp tibial relating to the palp tibia, the last but one segment of the palp
Palp tarsus the terminal segment of the palp
Solenidion a hollow hair-like structure on the appendages of certain groups of mites - responds to chemical stimuli
Heteromorphic relating to a different morphological form of the same life stage. Alternatively, a stage that is very different in appearance to the other stages of its life cycle
Homeomorphic having a male that, apart from differences in the genitalia, resembles its respective female