Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Dome-shaped holodorsal shield with reticulate-tuberculate ornamentation, a pair of large gland openings, and bearing 15–34 pairs of setae
• Peritremes absent
• Tarsus I with elongate knobbed setae
• Sternal setae st1 off sternal shield, usually on small platelets (jugularia) or in soft cuticle
• Male genital opening mid-intercoxal

Key to genera

1. Tarsi II–IV with an intercalary sclerite between the basitarsus and telotarsus that bears setae ad3, pd3; palp apotele 3-tined; dorsal shield with 34 pairs of setae (19 podonotal, 15 opisthosomal).............................. 2
   -  Tarsi II–IV without a seta bearing intercalary sclerite between the basitarsus and telotarsus; palp apotele 2-tined; dorsal shield with only 15 pairs of setae (10 podonotal, 5 opisthonotal); Western North America .............................. Neoepicrius Moraza & Johnson

2. Genitoventral shield expanded behind coxae IV and capturing a gland and setae ZV1; palp tarsus with 15 setae; Holacrtic.............................. Epicrius C&F
   - Genital or genitoventral shield not expanded; palp tarsus with 14 setae.............................. 3

3. Dorsal shield with short pilosities; st4 on metasternal shield; tarsus I with 4 clubbed macrosetae; Eastern North America.............................. Adenoepicrius Moraza
   -  Most dorsal shield setae stout, strongly barbed with long pilosities; st4 in soft cuticle; tarsus I with 3 clubbed macrosetae; Palearctic.............................. Berlesiana Turk

Diagnosis

Yellow, tan or dark red brown mites, with a hypotrichous, domed holodorsal shield covered in polygonal reticulum of tubercles and bearing a pair of large dorsolateral gland openings. First pair of sternal setae on jugularia or in soft cuticle; st2–3 on common sclerite; st4 in soft cuticle or on platelets. Genital shield axe- to tongue-shape, with 1–2 pairs of setae. Inguinal glands on small platelets behind coxae IV. Anal opening with 2 valves in small anal shield with 3–5 setae. Peritremes absent or minute. Tarsus I without claws, usually with slender clubbed setae; tibia I sometimes with a minutely clubbed seta. Palp genu with 6 setae; palp apotele with 2 or 3 tines. Epistome denticulate; hypostomal setae in triangular array; hypostomal groove broad, with denticles; corniculi slender, horn-like. Chelicerae chelate-dentate; pilus dentilis setiform; cheliceral setaa elongate, laterad and parallel to digits. Male genital opening on intercoxal shield, valve with or without a pair of setae; neither chelicerae nor legs obviously modified for sperm transfer.

Similar taxa

Species of Epicriopsis (Ameroseiidae) have claws and empodium on legs I and well developed peritremes. The presence of peritremes also serves to distinguish species of Podocinidae, and along with divided dorsal shields, some Ologamasidae (Euepicrius), and some Ascidae (Antennoseius) that have convergent elongate legs I and polygonal idiosomal ornamentation.

References

• Evans 1955bEvans 1955b:
  Evans EO. 1955b. A revision of the family Epicriidae (Acarina: Mesostigmata). Bulletin of the British Museum (Natural History) Zoology 3: 171–200.
• Gilyarov and Bregatova 1977Gilyarov and Bregatova 1977:
  Gilyarov MS, Bregatova NG, eds. 1977. Handbook for the identification of soil-inhabiting mites, Mesostigmata. Zoological Institute of the Academy of Sciences, Petrograd.
• Johnston 1982bJohnston 1982b:
  Johnston DE. 1982b. Mesostigmata. pp. 112–116. In: Parker SP, ed. Synopsis and classification of living organisms, Vol. 2. McGraw-Hill, New York.
• Krantz 1978Krantz 1978:
  Krantz GW. 1978. A manual of acarology [2nd ed.]. 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.
• Moraza 2005Moraza 2005:
  Moraza ML. 2005. A new genus and species of Epicriidae (Acari: Mesostigmata) from eastern North America. The Canadian Entomologist 137: 539–550.
• Moraza and Johnston 2004Moraza and Johnston 2004:
  Moraza ML, Johnston D. 2004. Neoepicrius, gen. n. from Western North America (Acari: Mesostigmata: Epicriidae). Acarologia 44: 195–207.