Pedipalpal form

a) pincer-like, chelate

Scorpions and pseudoscorpions have independently derived chelate pedipalps that resemble the chelae of crabs. These are used to grasp and manipulate prey, and in many pseudoscorpions pedipalps are also used to deliver a venom to the prey.

Misinterpretations allowed: Amphipods often have chelate thoracic appendages that could be confused with chelate pedipalps. (You can choose to disable "Allow misinterpretations" in the Preferences (gear icon) options.)

b) spiny raptorial

Many arachnids use their pedipalps to capture prey. In most whipscorpions (Amblybygida, Thelyponida, Schizomida) the pedipalps are massive, spine-covered structures that are used to capture and mash prey during external digestion. Some mites and opilionids have similarly modified pedipalps.

c) with palp thumbclaw complex

Some acariform mites have secondarily pincer-like palps formed by a hypertrophied distal palptibial seta (the claw) and an often swollen palptarsus (the thumb). The arrangement is called a thumb-claw process and is useful in separating groups of Prostigmata.

d) long and leg-like

A leg-like pedipalp was probably the primitive condition in arachnids and is retained or newly derived in a number of taxa. For example, many mygalomorph spiders often have long, leg-like palps; solfugids have leg-like palps ending in an adhesive pad; many mites and opilionids have rather long palps.

Misinterpretations allowed: Pedipalps are found only in arachnids, but some insects have very long palps that are rather leg-like. This is especially true in the primitive jumping bristletails. Also, palps are typically long in crustaceans. (You can choose to disable "Allow misinterpretations" in the Preferences (gear icon) options.)

e) pedipalps reduced (1-4 segments)

The pedipalps of mites have a maximum of 5 free segments (trochanter, femur, genu, tibia, tarsus). In all mites the palp coxae are fused to form the subcapitulum. In most mites the palp tarsal claws (apotele) have been lost or reduced to a subdistal, 2-4 toothed structure.

f) elbowed (geniculate)

Ricinuleids and some mites (e.g., snout mites, Bdelloidea) have distinctly elbowed palps, with a large basal segment and distal segment(s) that diverge at a sharp angle.

g) absent, minute, or withdrawn

Pedipalps are prominent in most arachinids, but are reduced or absent in some mites (e.g., hypopal astigmatans).

Is it a mite?—Key feature pages