Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Adult females with a truncate dorsal shield extending somewhat onto the opisthonotal region
• A median double-oval (lazy-8) posterior pygidial sclerite
• Chelicerae enlarged and with a bifurcate pilus dentilis

Diagnosis

Brown and white, with truncate dorsal shield exposing much of opisthosoma of female; opisthonotal region with pairs of small mesonotal scutella and a minute, lazy-8 shaped pygidial sclerite.  Sternal shield large, with 3 pairs of setae (st1–3), 3 pairs of lyrifissures (stp1–3), and fused endopodal elements I-II; st4 in soft cuticle; genital shield axe-shape, nude, flanked by 2 pairs of setae in soft cuticle; inguinal glands on small platelets behind coxae IV; anal opening with 2 valves in small anal shield. Peritremes relatively short, reaching anterior margin of coxa II, peritrematal shield poorly developed and fused to dorsal shield anteriorly. Tarsus I with or without claws. Palp genu with 6 setae; palp apotele with 3 tines. Tectum mucronate and coarsely denticulate; hypostomal setae in triangular array; subcapitular gutter broad, with denticles; corniculi horn-like. Chelicerae chelate-dentate to chelate serrate; pilus dentilis short, broad and bifurcate. Male with holodorsal shield; genital opening on intercoxal shield, valve with a pair of setae; chelicerae not obviously modified for sperm transfer, but legs II and IV with spurs.

Similar taxa

Species of Proarctacarus have a very short podonotal shield and a series of small mesonotal platelets. Laelapidae (Hypoaspis, Gaeolaelaps), Parasitidae, Veigaiidae all are somewhat similar in form to Arctacarus, but none have the posteriorly truncate dorsal shield, lazy-8 pygidium, and bifurcate pilus dentilis, nor males with a mid-coxal genital opening.

Known species

• Arctacarus rostratus Evans 1955 [Type]
• Arctacarus beringianus Bregetova 1977
• Arctacarus dzungaricus Bregetova 1977

References

• Bregatova 1977Bregatova 1977:
  Bregetova NG. 1977. Fam. Arctacaridae Evans, 1955. pp. 145–148. In: Gilyarov MS and Bregetova NG, eds. A key to soil-inhabiting mites: Mesostigmata. Nauka, Leningrad.
• Evans 1955aEvans 1955a:
  Evans EO. 1955a. A collection of mesostigmatid mites from Alaska. Bulletin of the British Museum (Natural History) Zoology 2: 285–307.
• Makarova 2003Makarova 2003:
  Makarova OL. 2003. New genus and three new species of mites of the family Arctacaridae (Parasitiformes, Mesostigmata) from North America. Zoologicheskii Zhurnal 82: 919–936.