Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Adult females with a truncate pododorsal shield, a series of mesonotal platelets, and 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 (deutonymph has separate opisthonotal shield); 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 Arctacarus have a more extensive dorsal shield that encroaches onto the opisthonotal region. 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.

References

• 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.