Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Adults with 2 dorsal shields, each with serrate to crenulate margins with interspersed marginal setae and usually with 4 deep semi-circular depressions (fossae) on the posterior shield
• Peritrematal shields broad, bearing 1–3 pairs of setae
• Peritremes typically short in adults, often comma-shaped
• Euanal setae may be present

Diagnosis

Brown, yellow or pinkish, oval to subrectangular mites with separate podonotal and opisthosomal shields usually bearing r-R series and often with serrate margins; often somewhat hypertrichous; podonotal shield usually with 4 deep depressions near its posterior margin at the insertion of major dorso-ventral muscles, and bearing ventral seta JV5. Female sternal shield with 3 pairs of setae (st1–3) and 2 pairs of lyrifissures (stp1–2); st4 and stp3 usually on small metasternal platelets; epigynial shield axe-shape, with 1 pair of setae; inguinal glands on small platelets between base of epigynial shield and coxae IV or in soft cuticle; anal opening with 2 valves (often with a pair of euanal setae) in large ventrianal shield, free from truncate peritrematal shield or fused to peritrematal-metapodal shields. Peritremes usually short in adults (less than anterior margin of coxa II), but longer in deutonymphs, on broad shields bearing 1–3 pairs of setae. Tarsus I with claws. Palp genu with 6 setae; palp apotele with 2 tines. Tectum denticulate to spinose; subcapitular gutter often with pencil-like rows of ridges; corniculi horn-like; hypostomal setae in triangular array; hypostomal groove broad, with denticles. Chelicerae chelate-dentate; pilus dentilis setiform. Male genital opening on intercoxal shield, valve with a pair of setae; neither chelicerae nor legs obviously modified for sperm transfer.

Similar taxa

Heatherellidae have elaborate setae on the margins of the their shields, but also have large, spout-like gland openings and subdivided opisthonotal shielding. Some ascids (Ascinae) may seem superficially similar to zerconids, but lack deep pits and serrate margins on the dorsal shield, as well as having a reduced chaetotaxy, seta JV5 fully ventral, and a dermanyssine reproductive system. Adult female Coprozercon (Coprozerconidae) lack a opisthonotal shield.

References

• Blaszak 1974Blaszak 1974:
  Blazak C. 1974. Zerconidae (Acari, Mesostigmata) Polski. Monografie Fauny Polski. 3: 315 pp.
• Blaszak et al. 1995Blaszak et al. 1995:
  Blazak C, Cokendolpher JC, Polyak VJ. 1995. Paleozercon cavernicolous, n. gen., n. sp., fossil mite from a cave in the southwestern USA (Acari, Gamasida: Zerconidae), with a key to Nearctic genera of Zerconidae. International Journal of Acarology 21: 253–259.
• 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.
• Halaskova 1969Halaskova 1969:
  Halaskova V. 1969. Zerconidae of Czechoslovakia (Acari: Mesostigmata). Acta Universitatis Carolinae, Biologica 3–4: 175–352.
• 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 and Lindquist 1998Moraza and Lindquist 1998:
  Moraza ML, Lindquist EE. 1998. Coprozerconidae, a new family of zerconoid mites from North America. Acarologia 39 (4): 292–313.
• Walter 1988bWalter 1988b:
  Walter DE. 1988b. Nematophagy by soil arthropods from the shortgrass steppe, Chihuahuan desert, and Rocky Mountains of the central United States. Agriculture, Ecosystems & Environment 24: 307–316.