Is it a mite?

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Nomenclature

Amblypygi (Amblypygida)

Common names

whip spiders, tail-less whip scorpions, amblypygids

Probability of encounter

low

Quarantine importance

No known importance. Whip spiders may look fierce, but are not venomous and do not appear to have the potential for outbreaks. Some species are used in the pet trade and some may have small, threatened populations.

Similarity to mites

Much larger than mites and with clear opisthosomal segmentationsegmentation:
in mites distinct external segments have been lost but remnants of segmentation may be represented by hysterosomal folds or transverse arrays of setae and other cuticular sense organs.  In theory, all chelicerates have a prosoma composed of 6 segments (cheliceral, pedipalpal, and four leg-bearing segments = body segments I-VI).  Ventrally the positions of the prosomal segments can be identified by the insertions of their appendages, but dorsally they are obscured.  The opisthosoma is thought to comprise an additional 12-13 segments (body segments VII-XVIII or XIX), but appears to be somewhat to much reduced in most mites, except possibly Opilioacarida.  In early derivative Acariformes (e.g., many Endeostigmata), hysterosomal folds are thought to represent segmentation and in the Grandjean system are designated (from the sejugal furrow to the anus): C, D, E, F, H, PS AD, AN, PA.  There is disagreement in the literature over the origin of 'segments' C and D.  Adherents of Grandjean consider them to be opisthosomatic (with C probably representing a fusion of the pregenital [body segment VII] and genital [VIII] segments).  Others believe that C and D are the dorsal regions of the last two prosomal segments that bear leggs III and IV (i.e., body segments V & VI).
. More likely to be confused with spiders.

Morphology

Normal adult length: >20 mm
Bodybody:
the idiosoma of mites.
tagmata: prosomaprosoma:
(= cephalothorax) the anterior body region in arachnids; usually not distinct in mites.
, opisthosomaopisthosoma:
(= abdomen) the posterior body division in arachnids; usually not distinct in mites because of the fusion of the opisthosoma with part of the prosoma to form the idiosoma.

Eyes: 3 + 2 + 3 arrangement of ocelliocellus:
(pl. ocelli) a simple eye.  Mites with eyes usually have one or two pairs of lateral ocelli, but some Opilioacarida have three pairs.  Additionally, some acariform mites have one or two median ocelli on the underside of the naso.

Antennae: absent
Mouthparts: 2-segmented fang-like chelicerae; robust, spiny-raptorialraptorial:
(Latin raptor = robber) modified for capturing prey; predatory.  The pedipalps (e.g., many Cunaxidae) or legs I may be raptorial in mites.
palps
Legs: 4 pairs; legs I antenniform
Distinguishing features: segmented opisthosomaopisthosoma:
(= abdomen) the posterior body division in arachnids; usually not distinct in mites because of the fusion of the opisthosoma with part of the prosoma to form the idiosoma.
, stabbing chelicerae, 'tail' absent, pedicel (waist), whip-likewhip-like:
long, slender and sinuous as in the posterior setae of some phytoseiid mites (Mesostigmata) or the stylets of spider mites and their relatives (Prostigmata: Tetranychoidea).
legs I with subdivided tarsitarsus:
(pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).

Diversity

5 families, 17 genera, >136 species

References

• Harvey 2003
• Weygoldt 2000Weygoldt 2000:
  Weygoldt P. 2000. Whip spiders: Their biology, morphology and systematics. Apollo Books, Stenstrup.