Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Phytoseiidae with opisthonotal setaeseta:
  (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
  except R1, J5, Z4–5 suppressed
• All dorsal setaeseta:
  (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
  except J5 paddle-shaped
• r3 on dorsaldorsal:
  relating to the upper or back side; opposed to ventral.
  shield, R1 in soft cuticle
• JV5 paddle-shaped; setaseta:
  (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
  s6 absent but z6 present, z3 present.
• Z4–5 with insertions distant
• Genugenu:
  (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
  II with 6 setaeseta:
  (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
  ; genugenu:
  (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
  III with 6 setaeseta:
  (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
  ; no marcosetae on legs.

Similar taxa

Dorsaldorsal:
relating to the upper or back side; opposed to ventral.
chaetomes composed of spatulate setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
occur sporadically in other groups, but only Chantia paradoxa has such a highly reduced chaetomechaetome:
a complement of setae; the setal array present on a stage or body part.
with only 4 pairs of opisthonotal setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
.

Key to genera of Phytoseiinae

1. Setaseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   z3 absent, s6 present.............................. Platyseiella Muma
   - Setaseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   z3 present, s6 present or absent............................... 2

2. Setaseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   z6 absent, s6 present; dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield setaeseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   barbed, usually acicular, fine to thickened.............................. Phytoseius Ribaga
   - Setaseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   z6 present, s6 absent; dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield setaeseta:
   (pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
   spatulate/paddle-shaped.............................. Chantia Pritchard & BakerPritchard & Baker:
   A system of setal designations of spider mites in  Pritchard & Baker 1955 (A revision of the spider mite family Tetranychidae.  Mem. Pac. Coast Entomol. Soc. 2: 1-472.).  Dorsocentrals: D1 = c1; D2 = d1; D3 = e1; D4 = f1; D5 = h1; Dorsolaterals: L1 = c2; L2 = d2; L3 = e2; L4 = f2; Sublaterals: 1st sublaterals = c3; 2nd sublaterals = d3; 3rd sublaterals = e3; Humerals: H = c3;  also Inner sacrals (or DC4) = f1; Outer sacrals (or L4) = f2; Clunals (or DC5) = h1 or f3; Postanals (or posterior para-anals) = h2; Anterior para-anals = h3; Anals = ps1-3; 1st genitals (or anteromedial genitals) = g1; 2nd genitals (or posterolateral genitals)= g2;  Pregenitals = ag in the Grandjean system.
   

Ecology and distribution

Only one specimen is known from a collection in central Africa.

References

• Chant and McMurtry 1994Chant and McMurtry 1994:
  Chant DA, McMurtry JA. 1994. A review of the subfamilies Phytoseiinae and Typhlodrominae (Acari: Phytoseiidae). International Journal of Acarology 20: 223–310.