Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Opisthonotal region of dorsal shield with only 5 pairs of setae and J1–4 missing
• Female without metasternal plates and with anal shield
• Male without metasternal setae
• Median lobes of pulvillus of legs II–IV acute
• Genu II with 9 setae (pl2 absent)
• Paranal setae inserted slightly anterior to posterior margin of anal opening
• Legs II–IV with median lobe of pulvillus blunt
• Anterior rostral and internal palp trochanter setae extremely long, whip-like, tapering only near tip
• Phytoseiid-type sperm access system
• Fixed cheliceral digit with a deep receptacle that receives the tip of the movable digit
• Male lacking metasternal setae
• Post-stigmatic peritrematal extension absent

Similar taxa

Key to females of genera of Platyseiinae

1. Opisthonotal region of dorsal shield markedly hypotrichous, with only 5 pairs of setae (Z1, Z4, Z5, S4, J5); sternal setae st4 in soft cuticle; with anal shield; median lobes of pulvillus of legs II–IV blunt.............................. Cheiroseiulus
   - Opisthonotal region of dorsal shield with 12–15 pairs of setae; with metasternal plates bearing st4 and ventrianal shield; median lobes of pulvillus of legs II–IV acute.............................. 2

2. Opisthonotal region of dorsal shield with 2–4 pairs of setae in J-series; first pair of sternal setae (st1) distinctly shorter than third pair (st3); distance between fifth and sixth rows of deutosternal denticles nearly twice that between fourth and fifth rows; tibia II with 9 setae (pd1 absent).............................. Platyseius
   - Opisthonotal region of dorsal shield with 5 pairs of setae in J-series; 1st and 3rd pairs of sternal setae subequal in length; distance between 5th and 6th rows of deutosternal denticles similar to that between 4th and 5th rows; tibia II with 10 setae (pd1 present).............................. Cheiroseius

Ecology and distribution

Cheiroseiulus reniformis Evans and Baker was collected from a phytotel, a water-filled epiphyte.

References

• Evans and Baker 1991Evans and Baker 1991:
  Evans GO, Baker A. 1991. A new genus of the mite subfamily Platyseiinae from Jamaica (Parasitiformes: Ascidae). Journal of Zoology-(London) 224 (1): 121–126.  
• Evans and Hyatt 1960Evans and Hyatt 1960:
  Evans GO, Hyatt KH. 1960. A revision of the Platyseiinae (Mesostigmata: Aceosejidae) based on material in the collections of the British Museum (Natural History). Bulletin of the British Museum (Natural History) Zoology 6 (2): 27–101.
• Evans and Till 1979Evans and Till 1979:
  Evans EO, Till WM. 1979. Mesostigmatic mites of Britain and Ireland (Chelicerata: Acari-Parasitiformes): An introduction to their external morphology and classification. Transactions of the Zoological Society of London 35 (2): 145–270.
• Halliday et al. 1998Halliday et al. 1998:
  Halliday RB, Walter DE, Lindquist EE. 1998. Revision of the Australian Ascidae (Acarina: Mesostigmata). Invertebrate Taxonomy 12: 1–54.
• Karg 1993Karg 1993:
  Karg W. 1993. Acari (Acarina), Milben Parasitiformes (Anactinochaeta) Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59: 1–523.
• Kitching and Callaghan 1982Kitching and Callaghan 1982:
  Kitching RL, Callaghan C. 1982. The fauna of water-filled tree holes in box forest in south-east Queensland. Australian Entomological Magazine 8: 61–70.
• Krantz 1962Krantz 1962:
  Krantz GW. 1962. Acari. Free-living Mesostigmata. II. The family Aceosejidae. Parc National de la Garamba - Mission H. de Saeger 34: 3–29.
• Krantz 1986Krantz 1986:
  Krantz GW. 1986. A manual of acarology [2nd ed., emended 1986]. Oregon State University Book Stores, Corvallis.
• Krantz and Ainscough 1990Krantz and Ainscough 1990:
  Krantz GW, Ainscough B. 1990. Mesostigmata. pp. 583–665. In: Dindal DL, ed. Soil biology guide. John Wiley & Sons, Brisbane.
• Lindquist 2003Lindquist 2003:
  Lindquist EE. 2003. Observations on mites of the subfamily Platyseiinae, with descriptions of two new species of Platyseius from North America (Acari: Mesostigmata: Ascidae). pp. 155–182. In: Smith IM, ed. An acarological tribute to David R. Cook. Indira Publishing House, West Bloomfield.