Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Ascinae with completely divided dorsal shielddivided dorsal shield:
  in Mesostigmata, adult mites have two usually subequal dorsal shields.
  without transverse lines extending across surface
• Paranal setaeparanal setae:
  (also adanal setae) the pair of seta inserted laterad the anal opening in the Mesostigmata; usually designated pa or PAR; the anterior (= h3) and posterior (= h2) para-anals in the Pritchard & Baker System.
  inserted closer to posteriorposterior:
  the back part of the body or towards that region in comparison, e.g., 'posterior to'.
  margin of anus than to anterior margin
• Genugenu:
  (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
  IV with 9 setae (pl1 present); tibiatibia:
  (pl. tibiae) the leg segment between the genu and the tarsus.
  IV with 10 setae (pl2 present).
• Sternal porepore:
  a pore-like opening or structure in the cuticle.  In Mesostigmata, lyrifissures and true pore openings are often difficult to separate and both tend to be called 'pores', e.g., the sternal pores stp1-3.
  3 on sternal shieldsternal shield:
  a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
  
• Setae r3 and Z5 setiform, smooth to barbed
• Gnathotectumgnathotectum:
  (= 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.
  more or less smoothly trifurcatetrifurcate:
  split into three distally.
  
• Movable digit of chelicerae usually with 4–6 teeth, not serrateserrate:
  with closely set teeth that resemble the cutting edge of a saw.
  

Similar taxa

Similar taxa in key: Antennoseius Berlese, Ectoantennoseius Walter, Asca von Heyden, Protogamasellus Karg, Diseius Lindquist and Evans.

Key to adult females of Rhodacarus-like mites
(Rhodacaridae, Ologamasidae, Digamasellidae, Ascidae)

1. Arthrodial process simplesimple:
   unadorned; simple setae are needle-like and without hairs or pectins.
   .............................. 4
   - Arthrodial process produced as a brush.............................. 2

2. Basitarsusbasitarsus:
   a basal subdivision of the tarsus.
   IV with 4 setae (pl4 present).............................. Pararhodacarus
   - Basitarsusbasitarsus:
   a basal subdivision of the tarsus.
   IV with 3 setae (pl4 absent).............................. 3

3. 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 single median process or dentate.............................. Afrogamasellus
   - 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 median stalk y-shaped, usually with lateral tines.............................. Afrodacarellus

4. Scleronoduli present.............................. 5
   - Scleronoduliscleronoduli:
   3-4 light refractile structures, sometimes comma-shaped, in the podonotal region of many Rhodacaroidea and the genus Protogamasellus (Ascidae) in the Mesostigmata.  
   absent.............................. 10

5. Tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   I with 4 ventral setaeventral setae:
   in the Lindquist-Evans system used in the Mesostigmata, the ventral region has up to three longitudinal rows (Jv, Zv, Lv) with 1-5 transverse row designations.
   ; 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.............................. 6
   - Tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   I with 3 ventral setaeventral setae:
   in the Lindquist-Evans system used in the Mesostigmata, the ventral region has up to three longitudinal rows (Jv, Zv, Lv) with 1-5 transverse row designations.
   ; 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.
   2-tined.............................. 9

6. 3 scleronoduli (median unpaired);  j1–2, z1, and s1 on anterior margin of podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   .............................. 7
   - 4 scleronoduli (median pair +/- fused);  j1 (but not j2), z1 and s1 on anterior margin of shield.............................. 8

7. Pretarsustarsal apotele:
   (also pretarsus) the most distal segments of legs and palps bearing the claws and empodium
   I absent; without presternal plateletspresternal platelets:
   small sclerotized plates anterior to the sternal shield and laterad or posteriad the base of the tritosternum in some Mesostigmata.
   .............................. Rhodacarus (+Mediorhodacarus)
   - Pretarsustarsal apotele:
   (also pretarsus) the most distal segments of legs and palps bearing the claws and empodium
   I present; with 2 pairs of presternal plateletspresternal platelets:
   small sclerotized plates anterior to the sternal shield and laterad or posteriad the base of the tritosternum in some Mesostigmata.
   .............................. Rhodacaropsis

8. Podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   entire.............................. Rhodacarellus
   - Podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   divided between setae j3–j4; 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.
   denticulate-trifurcate.............................. Minirhodacarellus

9. Tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   I with 5 (rarely 4) dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   setae; 2 pairs of scleronoduliscleronoduli:
   3-4 light refractile structures, sometimes comma-shaped, in the podonotal region of many Rhodacaroidea and the genus Protogamasellus (Ascidae) in the Mesostigmata.  
   ; sternal shieldsternal shield:
   a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
   with 4 pairs of setae; anal opening normal.............................. Dendrolaelaps (Digamasellidae)
   - Tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   I with 6 dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   setae; 3 scleronoduliscleronoduli:
   3-4 light refractile structures, sometimes comma-shaped, in the podonotal region of many Rhodacaroidea and the genus Protogamasellus (Ascidae) in the Mesostigmata.  
   ; sternal shieldsternal shield:
   a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
   with 3 pairs of setae (st4 in soft cuticle); anal opening enlarged.............................. Protogamasellus mica Group (Ascidae)

10. Sternal seta st4 on sternal shieldsternal shield:
    a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
    .............................. 11
    - Sternal  seta st4 in soft cuticle.............................. 15

11. Anal opening large; tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    I with 5 dorsaldorsal:
    relating to the upper or back side; opposed to ventral.
    setae.............................. Digamasellus (Digamasellidae)
    - Anal opening normal; tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    I with 6 dorsaldorsal:
    relating to the upper or back side; opposed to ventral.
    setae.............................. 12

12. Sternal shieldsternal shield:
    a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
    strongly sclerotized throughout; tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    I with 4 ventral setaeventral setae:
    in the Lindquist-Evans system used in the Mesostigmata, the ventral region has up to three longitudinal rows (Jv, Zv, Lv) with 1-5 transverse row designations.
    .............................. Geogamasus (Ologamasidae)
    - Anterior region of sternal shieldsternal shield:
    a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
    poorly sclerotized, setae st1 in soft or granulate cuticle; tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    I with 3 ventral setaeventral setae:
    in the Lindquist-Evans system used in the Mesostigmata, the ventral region has up to three longitudinal rows (Jv, Zv, Lv) with 1-5 transverse row designations.
    .............................. 13

13. 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.
    2-tined; coxacoxa:
    the basal segment of the leg, articulating with (Parasitiformes) or fused to (Acariformes) the body wall.
    I without dorsaldorsal:
    relating to the upper or back side; opposed to ventral.
    spine .............................. 15
    - Palpapotele 3-tined: coxacoxa:
    the basal segment of the leg, articulating with (Parasitiformes) or fused to (Acariformes) the body wall.
    I with dorsaldorsal:
    relating to the upper or back side; opposed to ventral.
    spine.............................. 14

14. Presternal area granulate.............................. Protogamasellopsis
    - Presternal area with paired stacks of 4 presternal plateletspresternal platelets:
    small sclerotized plates anterior to the sternal shield and laterad or posteriad the base of the tritosternum in some Mesostigmata.
    .............................. Rhodacarella

15. Posteriorposterior:
    the back part of the body or towards that region in comparison, e.g., 'posterior to'.
    margin of podonotalpodonotal:
    relating to the dorsal podosoma, the region of the idiosoma over the legs.
    (at j6) and anterior margin of opisthonotalopisthonotal:
    dorsal opisthosoma.
    (at J1) shields with transverse lines; genugenu:
    (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
    IV with 8 setae, tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    IV with 9 setae.............................. Protogamasellus hibernicus Group (Ascidae)
    - Podonotalpodonotal:
    relating to the dorsal podosoma, the region of the idiosoma over the legs.
    and opisthonotalopisthonotal:
    dorsal opisthosoma.
    shields without transverse lines; genugenu:
    (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
    IV with 9 setae, tibiatibia:
    (pl. tibiae) the leg segment between the genu and the tarsus.
    IV with 10 setae.............................. Gamasellodes (Ascidae)

Key to genera in the subfamily Ascinae

1. With holodorsal shieldholodorsal shield:
   a shield that covers all of the dorsum.  In Mesostigmata, the holodorsal shield is often interpreted as resulting from the fusion of podonotal and opisthonotal shields and a suture between these regions is often visible (see recurved and procurved).
   that captures the R-series.............................. 2
   - Dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield divided into two subequal shields; R-series setae in softcuticle.............................. 3

2. Seta z1 present laterad seta j1 on anterior median region of dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield; femurfemur:
   (pl. femora) major leg segment between trochanter and genu; often subdivided into a basifemur and a telofemur.
   III with 7 setae; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   I with 13 setae; tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   II with 10 setae.............................. Orthadenella (Blattisociidae)
   - Seta z1 absent; femurfemur:
   (pl. femora) major leg segment between trochanter and genu; often subdivided into a basifemur and a telofemur.
   III with 6 setae; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   I with 12 setae; tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   II with 9 setae.............................. Neojordensia

3. Opisthonotal shieldopisthonotal shield:
   the posterior shield in mesostigmatans with divided dorsal shields.
   with 12 pairs of setae (J3, Z2, S1 absent); podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   lacking setae j2, z1, z3; adult leg setation strongly neotenous, genuagenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   I–II–III–IV with 11–8–7–7 setae, tibiaetibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   with 11–7–7–7 setae; female with anal shield.............................. Diseius
   - Opisthonotal shieldopisthonotal shield:
   the posterior shield in mesostigmatans with divided dorsal shields.
   with 15 or more pairs of setae (J3, Z2, S1 present); podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   with setae j2, z3, sometimes z1; adult leg setation not strongly neotenous, minimum number of setae on genuagenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   12–11–8–8, on tibiaetibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   13–10–8–9; female with anal or 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.
   .............................. 4

4. Hypostome with 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.
   bifid apically; anterior rostral setae thickened, spinelike; dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield setae z1 absent.............................. Anephiasca
   - Hypostome with 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.
   entire apically; anterior rostral setae of similar thickness to other hypostomal setae; dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shield setae z1 present or absent.............................. 5

5. Female with epigynialepigynal:
   (also epigynial) of or relating to the female genital opening or a shield protecting it.
   shield strongly rounded posteriorly and with small subtriangularsubtriangular:
   more or less triangular.  
   ventrianal or anal shield bearing 3–5 setae; male 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.
   united to peritrematalperitrematal:
   (peritrematic) of or referring to the peritreme; adjectival form of peritreme.
   shields; soft bodybody:
   the idiosoma of mites.
   cuticle often with microtuberculate striaestriae:
   the raised, narrowly aligned cuticular ridges, often like a fingerprint or plicate pattern; striations.
   .............................. 6
   - Female with epigynialepigynal:
   (also epigynial) of or relating to the female genital opening or a shield protecting it.
   shield truncate posteriorly and usually with 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.
   (rarely anal shield) bearing 3–9 setae (including circumanal setaecircumanal setae:
   in Mesostigmata, the three setae (postanal and pair of peranal) setae surrounding the anal opening.
   ); male 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.
   separate from peritrematalperitrematal:
   (peritrematic) of or referring to the peritreme; adjectival form of peritreme.
   shields; soft bodybody:
   the idiosoma of mites.
   cuticle striaestriae:
   the raised, narrowly aligned cuticular ridges, often like a fingerprint or plicate pattern; striations.
   without microtubercles.............................. 8

6. Palps elongated, at least half as long as leg I; palp trochantertrochanter:
   the leg segment between the coxa and the femur.
   longer than femurfemur:
   (pl. femora) major leg segment between trochanter and genu; often subdivided into a basifemur and a telofemur.
   ; palp tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   almost 3 times as long as tarsustarsus:
   (pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).
   .............................. Anystipalpus
   - Palps of normal length, about one-third as long as leg I; palp trochantertrochanter:
   the leg segment between the coxa and the femur.
   slightly shorter than femurfemur:
   (pl. femora) major leg segment between trochanter and genu; often subdivided into a basifemur and a telofemur.
   ; palp tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   twice as long as tarsustarsus:
   (pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).
   .............................. 7

7. Legs I with ambulacra and claws.............................. Antennoseius (Vitzthumia)
   - Legs I without ambulacra and claws.............................. Antennoseius (Antennoseius)

8. Opisthonotal shieldopisthonotal shield:
   the posterior shield in mesostigmatans with divided dorsal shields.
   with setae Z4 & S5 usually approximateapproximate:
   close together, near, adjacent
   and inserted together on pair of prominent posterolateral tubercles; podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   lacking setae z1,  j2 well behind level of j1; peritrematalperitrematal:
   (peritrematic) of or referring to the peritreme; adjectival form of peritreme.
   shields of adults broad, truncate posteriorly; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   I with 12 setae (av2 absent).............................. Asca
   - Opisthonotal shieldopisthonotal shield:
   the posterior shield in mesostigmatans with divided dorsal shields.
   with setae Z4, S5 well separated, not borne on pair of strong tubercles; podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   with setae z1 present; j2 tending to be displaced anteriorly, often in approximately transverse row with z1 and j1; peritrematalperitrematal:
   (peritrematic) of or referring to the peritreme; adjectival form of peritreme.
   shields of adults narrow or of moderate width, taperingtapering:
   drawn out or with margins converging.
   posteriorly; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   I with 13 setae (av2 present).............................. 9

9. Podonotal shieldpodonotal shield:
   the anterior shield in mesostigmatans with divided dorsal shields.  
   with transverse line extending across surface at level of setae z6, opisthonotal shieldopisthonotal shield:
   the posterior shield in mesostigmatans with divided dorsal shields.
   with similar line at level of setae J1; paranal setaeparanal setae:
   (also adanal setae) the pair of seta inserted laterad the anal opening in the Mesostigmata; usually designated pa or PAR; the anterior (= h3) and posterior (= h2) para-anals in the Pritchard & Baker System.
   inserted close to anterior margin of anus; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   IV with 8 setae (pl1 absent); tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   IV with 9 setae (pl2 absent).............................. Protogamasellus
   - Dorsaldorsal:
   relating to the upper or back side; opposed to ventral.
   shields without transverse lines extending completely across surface; paranal setaeparanal setae:
   (also adanal setae) the pair of seta inserted laterad the anal opening in the Mesostigmata; usually designated pa or PAR; the anterior (= h3) and posterior (= h2) para-anals in the Pritchard & Baker System.
   inserted closer to posteriorposterior:
   the back part of the body or towards that region in comparison, e.g., 'posterior to'.
   margin of anus than to anterior margin; genugenu:
   (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.
   IV with 9 setae (pl1 present); tibiatibia:
   (pl. tibiae) the leg segment between the genu and the tarsus.
   IV with 10 setae (pl2 present).............................. 10

10. Sternal porepore:
    a pore-like opening or structure in the cuticle.  In Mesostigmata, lyrifissures and true pore openings are often difficult to separate and both tend to be called 'pores', e.g., the sternal pores stp1-3.
    3 in soft cuticle; setae r3 and Z5 club-shaped, densely plumose; gnathotectumgnathotectum:
    (= 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.
    denticulate; movable digit of chelicerae serrateserrate:
    with closely set teeth that resemble the cutting edge of a saw.
    .............................. Ectoantennoseius
    - Sternal porepore:
    a pore-like opening or structure in the cuticle.  In Mesostigmata, lyrifissures and true pore openings are often difficult to separate and both tend to be called 'pores', e.g., the sternal pores stp1-3.
    3 on sternal shieldsternal shield:
    a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.
    ; setae r3 and Z5 setiform, smooth to barbed; gnathotectumgnathotectum:
    (= 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.
    more or less smoothly trifurcatetrifurcate:
    split into three distally.
    ; movable digit of chelicerae usually with 4–6 teeth, not serrateserrate:
    with closely set teeth that resemble the cutting edge of a saw.
    .............................. Gamasellodes

Ecology and distribution

These mites are small soil-inhabiting predators that feed on small invertebrates (e.g., nematodes, mites, springtails); reproduction is by arrhenotokyarrhenotoky:
a form of parthenogenesis (asexual reproduction) in which unfertilized eggs develop into male offspring. This typically occurs when an unfertilized female foundress disperses to a new habitat. After laying unfertilized eggs, males develop and mate with the female to produce both male and female offspring.
or thelytokythelytoky:
all-female pathenogenesis.  
.

References

• Evans and Till 1979Evans and Till 1979:
  Evans EO and 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.
• Halliday et al. 1998Halliday et al. 1998:
  Halliday RB, Walter DE, and Lindquist EE. 1998. Revision of the Australian Ascidae (Acarina: Mesostigmata). Invertebrate Taxonomy 12: 1-54.
• Hurlbutt 1970Hurlbutt 1970:
  Hurlbutt HW. 1970. Gamasellodes bicolor (Berlese, 1918) (Acarina: Ascidae) and its relatives. Acarologia 12: 474-8.
• Karg 1993Karg 1993:
  Karg W. 1993. Acari (Acarina), Milben Parasitiformes (Anactinochaeta) Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59: 1-523.
• Walter 1987Walter 1987:
  Walter DE. 1987. Life history, trophic behavior and description of Gamasellodes vermivorax n. sp. (Mesostigmata: Ascidae) a predator of nematodes and arthropods in semiarid grasslands. Canadian Journal of Zoology 65: 1689-1695.
• Walter 2003aWalter 2003a:
  Walter DE. 2003a. The genus Gamasellodes (Acari: Mesostigmata: Ascidae): New Australian and North American species. Systematic and Applied Acarology Special Publications 15: 1-10.
• Gwaiazdowicz and Walter 2005Gwaiazdowicz and Walter 2005:
  Gwaiazdowicz DJ and Walter DE. 2005. Gamasellodes tatricus sp. nov. (Acari: Ascidae) from Poland. Systematic and Applied Acarology 10: 61-66.
• Walter and Ikonen 1989Walter and Ikonen 1989:
  Walter DE and Ikonen EK. 1989. Species, guilds and functional groups: Taxonomy and behavior in nematophagous arthropods. Journal of Nematology 21: 315-327.
• Walter and Lindquist 1995Walter and Lindquist 1995:
  Walter DE and Lindquist EE. 1995. The distribution of asexual ascid mites (Acari: Parasitiformes) does not support the biotic uncertainty hypothesis. Experimental and Applied Acarology 19: 423-442.