Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Most species have a recurved peritreme and well-developed arthrodial brushes
• Adult females typically have a sternal shieldsternal shield:
  a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
  bearing 3 pairs of setae, setae st4 on a small metasternal shield, and a well developed ventrianal shieldventrianal shield:
  in Mesostigmata, a ventral shield bearing the anal opening, circum anal setae, and one or more pairs of ventral setae or pores (lyrifissures) [see anal shield]; maybe rather narrow or very broad and covering most of the gaster.
  

Key to adult females of some common genera of Macrochelidae

1. With ventrianal shieldventrianal shield:
   in Mesostigmata, a ventral shield bearing the anal opening, circum anal setae, and one or more pairs of ventral setae or pores (lyrifissures) [see anal shield]; maybe rather narrow or very broad and covering most of the gaster.
   bearing 9–13 setae.............................. 2
   - With anal shield bearing 3 circumanal setaecircumanal setae:
   in Mesostigmata, the three setae (postanal and pair of peranal) setae surrounding the anal opening.
   .............................. Neopodocinum

2. Vertical setae (j1) sessile on anterior dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield.............................. 3
   - Vertical setae (j1) on prow-like projection.............................. Holostaspella

3. Ventrianal shieldventrianal shield:
   in Mesostigmata, a ventral shield bearing the anal opening, circum anal setae, and one or more pairs of ventral setae or pores (lyrifissures) [see anal shield]; maybe rather narrow or very broad and covering most of the gaster.
   with 3 pairs of setae (+3 circumanals).............................. 4
   - Ventrianal shieldventrianal shield:
   in Mesostigmata, a ventral shield bearing the anal opening, circum anal setae, and one or more pairs of ventral setae or pores (lyrifissures) [see anal shield]; maybe rather narrow or very broad and covering most of the gaster.
   with 5 pairs of setae (+3 circumanals).............................. Geholaspis

4. Sternal shieldsternal shield:
   a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
   with raised polygonal ornamentation & enclosing most of genital shieldgenital shield:
   a shield or shields covering the genital opening; in female mongynaspine Mesostigmata this shield is usually called the epigynal (epigynial) shield.  
   .............................. Glyptholaspis
   - Sternal shieldsternal shield:
   a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
   variously ornamented, but without strongly raised reticulatereticulate:
   foveate - having a net-like ornamentation composed of irregular, rounded cells. Also having a net-like structure; usually referring to ornamentation on shields composed of irregular, angular cells.
   ornamentation and not strongly enclosing genital shieldgenital shield:
   a shield or shields covering the genital opening; in female mongynaspine Mesostigmata this shield is usually called the epigynal (epigynial) shield.  
   .............................. Macrocheles

Diagnosis

Yellow to dark brown dermanyssine mesostigmatans with holodorsal shields. Peritremes generally well developed and reflexedreflexed:
recurved, curved back on, as in the peritremes of Macrochelidae (Mesostigmata).
near stigmastigma:
the opening to the tracheal system.
. Sternal shieldsternal shield:
a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
often extending to either side of genital shieldgenital shield:
a shield or shields covering the genital opening; in female mongynaspine Mesostigmata this shield is usually called the epigynal (epigynial) shield.  
and bearing 3 pairs of setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
(st1–3) and 2 pairs of lyrifissures; metasternal shields present, bearing st4 and stp3; genital shieldgenital shield:
a shield or shields covering the genital opening; in female mongynaspine Mesostigmata this shield is usually called the epigynal (epigynial) shield.  
usually mound-shaped to subrectangular, and bearing 1 pair of setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
; ventrianal shieldventrianal shield:
in Mesostigmata, a ventral shield bearing the anal opening, circum anal setae, and one or more pairs of ventral setae or pores (lyrifissures) [see anal shield]; maybe rather narrow or very broad and covering most of the gaster.
narrow to broad with several pairs of ventral setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
and 3 circumanal setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
. Tarsustarsus:
(pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).
I without claws; trochantertrochanter:
the leg segment between the coxa and the femur.
I with 5 setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
; tibiatibia:
(pl. tibiae) the leg segment between the genu and the tarsus.
I with 5/3 dorsal/ ventral setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
, genugenu:
(pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
I with 5/2; genugenu:
(pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
IV with 6–7 setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
, 4/1 dorsal/ ventralventral:
relating to the lower or under side; opposed to dorsal.
. Chelicerae chelate-dentatechelate-dentate:
pincer-like chelicerae with teeth.
; movable digit without excrescences, but with well developed arthrodial brusharthrodial brush:
a brush like extension of the arthrodial membrane at the articulation of the movable and fixed digits in some Mesostigmata. Not to be confused with cheliceral excrescences that are produced from openings in the movable digit.
. Palppalp:
(= pedipalp) the second pair of limbs in arachnids, used in feeding and originating on either side of the chelicerae.  In mites, the palps may be vestigial, with only a few segments, or have a maximum of  5 freely articulating segments (rarely the femur is subdivided) and a distal or subdistal apotele.
genu with 6 setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
, palp apotelepalptarsal apotele:
(= palp apotele, palptarsal claw) the most distal segment of the palp; absent in Acariformes, claw-like in Opilioacarida, and a subdistal, tined structure in the Mesostigmata.
3-tined; corniculicorniculus:
(pl. corniculi) (also, external malae) a usually horn-like process (sometimes toothed, bifurcate, trifurcate, spine-like, spatulate, or membranous) on the subcapitulum of parasitiform mites that usually supports the salivary styli.  A toothed corniculus could be confused with a rutellum, a possibly homologous structure in Acariformes and Opilioacarida. Phytoseiid image is spatulate corniculus.
horn-like. Tritosternumtritosternum:
the sternum of the 3rd body segment (between legs I); produced as a biflagellate structure in Mesostigmata, although sometimes the flagellae (laciniae) are partially or completely fused.  
biflagellate with columnar basebase:
the usually columnar basal part of the tritosternum; sometimes expanded and rectangular or otherwise modified; the most basal part of any structure.
. Tectumgnathotectum:
(= epistome, tectum) an often membranous dorsal projection of the anterior margin of the basis capitulum in Mesostigmata; often diagnostic at family-, genus- or species-levels; also often difficult to see without high magnification and good optics.
with long median tine and often with lateral flag-like processes. Female sperm induction pores near bases of coxae IV.  Males with genital opening at basebase:
the usually columnar basal part of the tritosternum; sometimes expanded and rectangular or otherwise modified; the most basal part of any structure.
of tritosternumtritosternum:
the sternum of the 3rd body segment (between legs I); produced as a biflagellate structure in Mesostigmata, although sometimes the flagellae (laciniae) are partially or completely fused.  
in sternogenital shield; spermatodactylspermatodactyl:
(also spermadactyl) the 'sperm finger' on the chelicerae of male dermanyssine Mesostigmata used to transfer sperm to the secondary sperm system in the female; spermatodactyls take various forms, from simple finger-like processes to very long, contorted structures.  
usually well developed.

Similar taxa

Parholaspidids (lack recurvedrecurved:
a curved suture or line of dehiscence that arches posteriorly; opposed to procurved.
peritreme); some Ascidae and Pachylaelapidae: Zygoseius (lack arthrodial brusharthrodial brush:
a brush like extension of the arthrodial membrane at the articulation of the movable and fixed digits in some Mesostigmata. Not to be confused with cheliceral excrescences that are produced from openings in the movable digit.
).

References

• Adis and Krantz 1985Adis and Krantz 1985:
  Adis J, Krantz G. 1985. Notes on the natural history of Macrocheles (Acari: Gamasida: Macrochelidae) associated with 3-toed sloths Bradypus spp. (Edentata: Bradypodidae) in the central Amazon. Zoologische Anzeiger 214: 222–224.
• Evans and Browning 1956Evans and Browning 1956:
  Evans GO and Browning E. 1956. British mites of the subfamily Macrochelinae Trägårdh (Gamasina - Macrochelidae). Bulletin of the British Museum (Natural History) Zoology 4: 4-55 + Plates I-IV.
• Evans and Hyatt 1963Evans and Hyatt 1963:
  Evans GO and Hyatt KH. 1963. Mites of the genus Macrocheles Latr. (Mesostigmata) associated with coprid beetles in the collections of the British Museum (Natural History). Bulletin of the British Museum (Natural History), Zoology 9: 327-401.
• Halliday 1986aHalliday 1986a:
  Halliday RB. 1986a. Mites of the genus Glyptholaspis Filipponi and Pegazzano (Acarina: Macrochelidae) in Australia. Journal of the Australian Entomological Society 25: 71-74.
• Halliday 1986bHalliday 1986b:
  Halliday RB. 1986b. Mites of the Macrocheles glaber group in Australia (Acarina: Macrochelidae). Australian Journal of Zoology 34: 733-752.
• Halliday 1988Halliday 1988:
  Halliday RB. 1988. The genus Holostaspella Berlese (Acarina: Macrochelidae) in Australia. Journal of the Australian Entomological Society 27: 149-155.
• Halliday 1990aHalliday 1990a:
  Halliday RB. 1990a. Mites of the Macrocheles muscaedomesticae group in Australia (Acarina: Macrochelidae). Invertebrate Taxonomy 3: 407-430.
• Halliday 2000Halliday 2000:
  Halliday RB. 2000. The Australian species of Macrocheles (Acarina: Macrochelidae). Invertebrate Taxonomy 14: 273-326.
• Halliday and Holm 1985Halliday and Holm 1985:
  Halliday RB & Holm E. 1985. Experimental taxonomy of Australian mites in the Macrocheles glaber group (Acarina : Macrochelidae). Experimental and Applied Acarology 1: 277-286.
• Kinn and Witcosky 1977Kinn and Witcosky 1977:
  Kinn DN and Witcosky JJ. 1977. The life cycle and behaviour of Macrocheles boudreauxi Krantz. Zeitschrift für Angewandte Entomologie 84: 136-144.
• Krantz 1983Krantz 1983:
  Krantz GW. 1983. Mites as biological control agents of dung-breeding flies, with special reference to the Macrochelidae. pp. 91-98. In: Hoy MA, Cunningham GL, and Knutson L, eds. Biological control of pests by mites. University of California Agriculture Experiment Station, Special Publication 3304, Berkley.
• Krantz and Wernz 1979Krantz and Wernz 1979:
  Krantz GW and Wernz JG. 1979. Sperm transfer in Glyptholaspis americana. pp. 441-446. In: Rodriguez JG, ed. Recent advances in acarology, Vol. 2. Academic Press, New York.
• Walter 1988aWalter 1988a:
  Walter DE. 1988a. Macrocheles schaeferi (Acari: Mesostigmata: Macrochelidae), a new species in the subbadius group from grassland soils in the central United States. Annals of the Entomological Society of America 81: 386-394.
• Walter and Krantz 1986aWalter and Krantz 1986a:
  Walter DE and Krantz GW. 1986a. Description of the Macrocheles kraepelini species complex (Acari: Macrochelidae) with two new species. Canadian Journal of Zoology 64: 212-217.
• Walter and Krantz 1986bWalter and Krantz 1986b:
  Walter DE and Krantz GW. 1986b. A review of the glaber group (s. str.) species of the genus Macrocheles (Acari: Macrochelidae) and designation of species complexes. Acarologia 27: 277-294.