Ricinuleida (Ricinulei)

Common names: ricinuleids

Probability of encounter: low

Quarantine importance: no known importance, although of potential conservation concern as threatened cave or rainforest dwelling species.

Similarity to mites: hexapod larvae, gnathosoma, more or less mite-like build; however, ricinuleids have opisthosomas with three series of dorsal sclerites and clear ventral segmentation.

Morphology

Normal adult length: <10 mm
Body tagmata: gnathosoma, prosoma, idiosoma
Eyes: lens absent (pigment spot may be present)
Antennae: absent
Mouthparts: 2-segmented chelicerae; long, elbowed palps
Legs: 4 pairs (3 pairs in larvae); tarsi I & II with sensory pits
Distinguishing features: cucullus (shelf over mouthparts), elbowed palps, postabdomen

Comments: Ricinuleids and mites (Acari) are the only arthropods with a capitulum, i.e. with the cheliceral and pedipalpal segments separated from the remainder of the prosoma by a circumcapitular groove.

Diversity: 1 family (Ricinoididae), 3 geographically +/- discrete genera (Brazil to Honduras: Cryptocellus; Panama to Texas: Pseudocellus; Africa: Ricinoides), >55 spp.

References

 

Harvey, M.S.  2003.  Catalogue of the smaller arachnid orders of the World.  CSIRO Publishing, Collingwood, Victoria