Glossary

abaxial: away from the axis of the body (midline), e.g., the outer or lateral face of a chelicera (also antiaxial)

abdomen: loosely used term usually referring to the opisthosoma or hysterosoma in mites

abjugal plane: (furrow) a mostly theoretical division between the podosoma and gnathosoma

acanthoides:  eupathidia

acarodomatium: (pl. acarodomatia) plant morphogenetic structures that serve as refugia for mites; hideaways at the juncture of two veins on the ventral surface of the leaves of certain plants that are often inhabited by predatory or fungivorous mites; also domatia

accessory seta: in the Eriophyoidea, opisthosomal seta h1

acetabulum: a concave cavity in the body wall where a leg or other structure is inserted; in brachypyline oribatids they may be cavities where the trochanter articulates with the coxae (which are fused to the body wall) and may contain tracheal stigmata; the genital opening and papillae of acariform mites are contained within an acetabulum; also, the concave portion of a ball and socket joint

aciniform: resembling a cluster of grapes

acrotarsus: (=apicotarsus) distal subdivision of the tarsus, usually of tarsus I (NB—not to be confused with the ambulacral stalk or pretarsus)

Actinedida: an alternative name for Prostigmata

actiniform: with radiating rays that resemble a sea anemone; actiniform cheliceral appendage of some Uropodoidea

actinopilin: optically active component of the core of birefringent setae in acariform mites that is resistant to maceration in lactic acid. The actinopilin core is surrounded by an isotropic layer that forms the outer surface. Actinopilin may occur in true setae (typical mechanoreceptors and trichobothria) and the eupathidia and famuli which have a protoplasmic core. Solenidia do not have actinopilin. (Also actinochitin)

Actinotrichida: an alternative name for Acariformes; referring to the presence of setae containing actinopilin, which exhibit birefringence under polarized light (see Anactinotrichida)

acuminate: coming to a point

adanal plate: (or adanal region) sclerites or sclerotized fields laterad the anal region; usually used in oribatid mite taxonomy and bearing adanal setae

adanal setae: setae on the adanal plate or region in acariform mites; paranal setae in Mesostigmata

adaxial: towards the axis of the body (midline), e.g., the inner face of a chelicera (also paraxial)

adgenital sclerite: (adgenital plate; inguinal pore plate) in gamasine Mesostigmata, a pair of small sclerites in the region of the posterior corners of the genital shield and parapodals IV that bears the inguinal glands gv2

adjacent: in reference to structures next to one another, contiguous; as opposed to separated

adoral: referring to setae distal on the subcapitulum of acariform mites (designations ao1, ao2)

aedeagus: a male intromittent organ, especially when sclerotized (e.g., in Tetranycoidea, Raphignathoidea); a penis is a flexible, membranous intromittent organ, although 'penis' is often used for aedeagi (e.g., in Astigmata)

aestivation: a period of dormancy or inactivity, similar to hibernation, but occurring during hot and dry conditions, typically in summer. This behavior helps certain mites and other organisms to survive harsh environmental conditions.

aff.: (also affin.) affinis (L. related to, adjacent to), used for uncertain species designations (e.g., Cosmolaelaps aff. vacua (Michael)), meaning 'similar to', and implying that the specimen referred to may represent a new species (see nr., sp. nr., and cf.)

aggenital plate: (also adgenital plate (or region)) sclerites or sclerotized fields on either side of the genital opening

alternating calyptostasy: the alternation of calyptostatic and elattostatic developmental stages as seen in Parasitengona, Pterygosomatidae, and some other Prostigmata

alveolus: a setal socket (also a single depression in alveolate ornamentation)

ambulacrum: the claws and empodium of the apotele or pretarsus (technically including the ambulacral stalk [confusingly sometimes also called 'pretarsus'] and apotele [empodium and claws])

Anactinotrichida: an alternative name for Parasitiformes, referring to the absence of setae containing actinopilin, which do not exhibit birefringence under polarized light (see Actinotrichida)

anal lobe: in the Eriophyoidea, the most posterior region of the body (segment PS) containing the anal opening and usually acting as an adhesive disk to anchor the body during feeding

anal pedicel: a stalk produced from a cement-like secretion from the anal opening of deutonymphal sejines and uropodines which is used to attach to a phoretic host

anal seta: any seta on an anal valve or ascribed to the anal region; pseudanal setae ps1–3 in spider mites; true anal setae may be present in acariform mites that add segment AN

anal shield: in Mesostigmata, a ventral shield bearing the anal opening and circumanal setae (po, pa), but without any ventral setae or pores (lyrifissures) [see ventrianal shield]

anal sucker plate: the complex attachment organ on the posterior venter of astigmatan hypopi

anal suckers: a pair of modified setae near the anal opening of male Astigmatina that act as suckers for holding onto females during precopula and mating

anal valve: a shield protecting the anal opening

Anals: the pseudanal setae ps1–3 in the Pritchard & Baker System

anamorphosis: the addition of body segments (and their structures) during ontogeny; in Acariformes, additions occur behind the anal opening (pseudanal segment in the larva): anal (AN) in the protonymph, adanal (AD) in the deutonymph, peranal (PA) in the tritonymph

anarthric: an unjointed subcapitulum without a labiogenal suture or scissure

anemorhria: dispersal by air, as in spider mites and eriophyoid mites

annulate: with a ring-like ornamentation, especially the series of  annulations characteristic of the integument of some eriophyoid and endeostigmatic mites

annulus: (pl. annuli) a ring-like structure or ornamentation

anogenital region: the ventral region encompassing the genital, aggenital, anal and adanal sclerites in oribatid mites

antenniform: having the form of antennae, typically used for long slender legs I that often lack the apotele, or for palps that resemble antennae (e.g., Bdellidae)

anteriad: to the front (do not use with the preposition 'to' since this is part of the meaning of the word), e.g., 'setae ro are usually inserted anteriad setae le'

anterior: the front part of the body or towards that region in comparison, e.g., 'anterior to'

anterior dorsal seta: setae (see ad 1–3) on the anterior dorsal surface of a leg or palp segment in the Mesostigmata

anterior eye: the more anterior of a pair of lateral ocelli, usually having the more eye-like lens

anterior hypostomal setae: also hypostomtic setae; the most anterior (h1) of the three pairs of hypostomatic setae in the Mesostigmata; present in the larva

anterior para-anals: setae h3 in the Pritchard & Baker System

anterior shield seta: in the Eriophyoidea, the unpaired, median internal vertical seta vi ('single anterior shield seta') or the paired external vertical setae ve

anterolateral seta: either of the setae (al 1–2) on the anterior lateral surface of a leg or palp segment in the Mesostigmata

anterolaterals: (a) a pair of ventral setae between the subunguinal seta and the primiventrals on the tarsi of acariform mites (see whorl)

anteromedial seta: in Mesostigmata (e.g., Veigaiidae), palpgenual seta al1

anteroventral seta: a seta (av 1–3) on the anterior ventral surface of a leg or palp segment in the Mesostigmata

antiaxial: away from the axis of the body (midline), e.g., the outer or lateral face of a chelicera (also abaxial)

antiaxial lyrifissure: the lyrifissure on the outer face of the chelicera in Mesostigmata

apical: at the tip of a structure

apicotarsus: (=acrotarsus) distal subdivision of the tarsus, usually of tarsus I

apodeme: sclerotized invagination of the cuticle, often at the margin of a plate, that serves as attachment site for muscles

apoderm: a cuticle formed during development that lacks limbs and setae (see calyptostase)

apophysis: an internal projection from the body wall, often a site of muscle attachment

apotele: (Greek apotelein = to complete)—the terminus of an appendage; the most distal leg segment, often consisting of an empodium and a pair of claws. The apotele of a leg is usually treated as equivalent to the pretarsus or some part thereof (e.g., the claws and empodium), but the palptarsal apotele in Mesostigmata is a tined structure originating at the base of the palptarsus and thought to be a remnant of the claws. The chelicerae are also an appendage and terminate in the movable digit.

approximate: close together, near, adjacent

arborescent: branched like a tree, tree-like, dendritic

area porosae: usually round to oval aggregations of pore-like areas of the cuticle; usually referring to the octotaxic system of the Oribatida

area punctata: usually grape-like (aciniform) clusters of punctae on the sternal shields of some Mesostigmata

armored mite: any mite encased in armor, but especially members of the Oribatida and Uropodoidea

arolium: (pl. arolia) a membranous pouch-like structure; e.g., the cavity in which the empodia are situated in Neilstigmaeus (Prostigmata: Stigmaeidae)

arrhenotoky: 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.

arthrodial 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.

arthrodial corona: (arthrodial coronet) a crown-like array of fine processes from the arthrodial membrane at the juncture of the fixed and movable digits in Mesostigmata.

arthrodial membrane: the soft cuticle at any articulation, but often specifically used for the juncture of the movable and fixed digits in Mesostigmata.  The membrane may have a crown-like corona of fine processes or be extended into a brush-like structure.  

articulation: a region of differentiated cuticle joining two parts of an exoskeleton; a joint, scissure or furrow.

aspidosoma: the anterior dorsal region of the prosoma in acariform mites.

aspis: a sclerotized shield over the aspidosoma.

astegasime: having the chelicerae exposed dorsally: the rostral tectum is reduced or absent (see stegasime), as in many Prostigmata, Astigmata and some early derivative oribatids.

astigmatan: a member of the Astigmata; characteristic of or belonging to the Astigmata.

astigmatic: adjectival form of Astigmata.

astigmatid: incorrectly formed, but commonly used, adjectival form of Astigmata; an astigmatan.

Astigmatina: An alternative name for the hyporder Astigmata. While sometimes referred to as a "cohort," a term traditionally denoting a taxonomic rank between a class and an order, Astigmata represents a lineage between the ranks of order and family.

atelebasic rutellum: large rutellum with the apex expanded, toothed, and with a paraxial lobe as in Desmonomata and some Brachypylina.

atrium: in phytoseioid Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae), a valve-like region of the sperm access system which the major duct to the calyx and gives rise to the minor duct.

auxilary stylets: (= inner infracapitular stylets) a pair of stylets of uncertain origin in the bundle of 7-9 stylets in the Eriophyoidea.

basad: towards the base of a structure.

basal: towards the base of a structure; on a limb, towards the insertion on the body.

basal article: the most basal of the maximum of three segments of the chelicera; usually absent or obscure in Acariformes.

base: the usually columnar basal part of the tritosternum; sometimes expanded and rectangular or otherwise modified; the most basal part of any structure.

basifemur: a basal subdivision of the femur of the leg or palp.

basilar piece: the median internal structure with which the claws articulate in the ambulacrum of Mesostigmata.

basilar sclerite: a sclerotized structure to which the cheliceral muscle attach and which articulates with the movable cheliceral digit in some Prostigmata (analogous to the sclerotized node in some Uropodina).

basis capitulum: (also basis gnathosomatica) the sclerotized ring around the base of the capitulum in mesostigmatans and ticks; derived from dorsal and ventral extensions of the palpcoxae.  The basis capitulum bears the corniculi, internal malae, and hypostomal and palpcoxal setae ventrally and the gnathotectum (epistome) dorsally.

basitarsus: a basal subdivision of the tarsus.

bayonet-like: resembling a long, sharp blade used for stabbing, as in some corniculi; sword-like.

bdellid: a snout mite in the family Bdellidae (Prostigmata) (from the Greek for leech) usually with elbowed palps and often bright red in color (rarely purple).

bicuspid: having two points or cusps, e.g., the gnathotectum of some Mesostigmata.

biflagellate: with two whip-like processes as in many mesostigmatan tritosterna.

bifurcate: split into two distally or with two projections. 

bipectinate: a seta or other process having comb-like teeth on two sides (see pectinate).

biserrate: with saw-like teeth on two sides (see serrate).

bivalved: with two longitudinal plates or valve-like coverings.

blister mite: a species of Eriophyoidea that produces blister-like galls on the leaves of plants, typically flattened, subcircular swellings of the leaf surface over a cavity in the leaf lamina (parenchyma).

body: the idiosoma of mites.

body divisions: apparent subdivisions of the idiosoma in Acariformes.

bothridial sensillum: (= trichobothrium) an often elaborately modified seta set in a cup-like base; forms include filiform, ciliate, pectinate or variously thickened or clubbed (bat-like to globose to capitate).

bothridial seta: prodorsal seta bo (also sci or s1) in Acariformes; the bothridial sensillum or trichome.

bothridium: the cup-like base of a bothridial sensillum.

box mites: oribatid mites that exhibit ptychoidy, the ability to withdraw their limbs and close-up like a box.

brachypyline: having separate genital and anal plates surrounded by a large ventral plate (composed of aggenital and adanal elements); usage usually restricted to traditional oribatid mites (see macropyline).

brachytracheae: thick, elongated and porose tube-like invaginations in the cuticle of some oribatid mites.

broad mite: (also tea mite)  Polyphagotarsonemus latus (Banks) a plant-parasitic tarsonemid mite.

bruststiele: see Claparède's organ, urstigma

bud mite: a species of Eriophyoidea that galls buds on plants, e.g., the Filbert Big Bud Mites Phytoptus avellanae Nalepa (PHYTOPTIDAE) and Cecidophyopsis vermiformis (Nalepa) (ERIOPHYIDAE).

bulliform cells: large, bubble-shaped epidermal cells found in groups on the upper surface of leaves, particularly in monocots. They are typically located near the mid-vein and are thought to be involved in the folding and unfolding of leaf tissue, helping to control light intensity and reduce water loss.

bursa copulatrix: a secondary sperm system opening terminally in some Prostigmata and Astigmatina.

californicus: the phytoseiid mite Neoseiulus (also Amblyseius) californicus (McGregor), a generalist predator used in a variety of cropping systems.  Also the California mite.

calyptostase: (adj. calyptostatic) one of the abnormal stases recognized by Grandjean where neither mouthparts nor legs are functional, e.g., most prelarvae; the protonymph and tritonymph in Parasitengona.  A calyptostase may have no sign of limbs or setae so that only a cuticle remains (apoderm).  In such cases (e.g., the prelarvae of most oribatids), the calyptostase is retained within the egg shell or the cuticle of the previous instar and is also an endostase.  In contrast the prelarvae of many Endeostigmata and some Prostigmata (e.g., Bdellidae) pop out of the egg and are considered ectostases (also see elattostase).

calyx: (= cervix) in phytoseioid Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae, Podocinidae), a collar-like structure of the sperm access system which surrounds the base of the vesicle.

camerostome: a recess under the rostral tectum that allows retraction of the chelicerae and palps of oribatid mites and that is sealed by the subcapitulum when retracted; a deep recess containing the gnathosoma in Uropodina.

capitate: with a terminal knob or head-like swelling; clavate; globose.

capitular capsule: (also gnathosomal capsule) the fused chelicerae and subcapitulum.

capitulum: (pl. capitula)  (= gnathosoma) the anteriormost part of a mite, composed of the cheliceral and pedipalpal segments and separated from the body (idiosoma) by a ring of soft cuticle.  Sometimes called the rostrum, infracapitulum, or hypostome.

capsule: as in gnathosomal capsule, the fused chelicerae and subcapitulum characteristic of Tarsonemina and some other Prostigmata (e.g., Cheyletoidea, Myobioidea) (also tegmen, rostral shield).

carapace: the shield covering the dorsal prosoma of arachnids; in some European literature, the mesostigmatan podonotal shield. 

carina: a longitudinal ridge.

caudal bend: the posteroventral curvature of the opisthosoma that results in the anal opening being ventral in most mites.  Opilioacarida have a terminal anus (the presumed primitive condition) and others have secondarily terminal or even dorsal anal openings.

caudally: in reference to the rear end.

caudalseta: in the Eriophyoidea, opisthosomal seta h2, often the longest seta on the mite and curled or whip-like.

cement layer: the outermost layer of the cerotegument; often produced in an ornamental pattern.

centrad: the orientation of a structure toward the center; in eriophyoid mites, often used to describe the direction of scapular setae (sc), which point toward the body’s central axis.

cephalothoracic shield: the prodorsal shield, especially in the Eriophyoidea.

cepheid: a member of the brachypyline oribatid family Cepheidae, the nymphs of which often carry elaborate scalps.

cerotegument: the outer layers of the epicuticle, including the wax and cement layers; often thin and inconspicuous, but sometimes very thick, ornamented, and obscuring the underlying cuticle; thick ceroteguments often can be peeled off to expose a very different-looking mite.

cervix: (= calyx) in phytoseioid Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae, Podocinidae), a collar-like structure of the sperm access system which surrounds the base of the vesicle.

cf.: confer (Latin is conferre - refer or compare to) used for uncertain species designations (e.g., Cosmolaelaps cf. vacua (Michael)), roughly meaning 'see or compare to', and implying that the specimen referred to may represent a new species or may simply be an unusual form of the attributed species (see nr., sp. nr., and aff.).

chaetome: a complement of setae; the setal array present on a stage or body part.

chaetotaxy: the use of setal position and form in taxonomy; see Lindquist-Evans system, Grandjean system, Rostral-lamellar system, etc.

chambered: a structure with discrete compartments, e.g., the peritremes of some ologamasids (Mesostigmata) and prostigmatans.

chela: a pincer, as in a pseudoscorpion's distal pedipalpal segments.

chelate: pincer-like, as in a crab's claws, a scorpion's pedipalps or many chelicerae; in water mites (Hydrachnida), chelate palps have a dorsal palptibial process opposed to a ventral movable palptarsus (opposed to uncate).

chelate-dentate: pincer-like chelicerae with teeth.

chelate-serrate: pincer-like chelicerae with a row of saw-like teeth (also serrate). 

chelicera: a limb on the presumed first body segment in chelicerate arthropods, the primary mouthparts.  In mites the chelicerae are primitively chelate-dentate, but may be modified into almost unrecognizable forms.  In Acariformes, the chelicerae are usually 2-segmented, but in other mites and some basal acariforms they have three segments.  Rarely, in some Uropodoidea (Mesostigmata), a subdivision makes them appear 4-segmented.

cheliceral: of or pertaining to the chelicera.

cheliceral guides: (= outer infracapitular stylets) a pair of capitular processes that frame the cheliceral stylets in the Eriophyoidea.

cheliceral retainer: the flexible, spine-like structure produced by the palpcoxal base and enclosing the cheliceral stylets in Eriophyoidea.

cheliceral seta: any seta on the chelicera of a mite; the often scale-like or otherwise modified seta on the dorsal surface of the chelicera in Mesostigmata.

cheliceral sheath: (= stylet sheath, rostral gutter) the median anterior process of the capitulum bearing a gutter, U-shaped in cross section, that enclosed the 7-9 stylets in the Eriophyoidea.

chelicerate: a member of the arthropod lineage Chelicerata that includes the horseshoe crabs, scorpions, spiders, mites and their relatives.

cheyletid: a member of the family Cheyletidae (Prostigmata).  Most members of the subfamily Cheyletinae are predatory and sometimes important in biocontrol; members of the Cheyletiellinae (sometimes given its own family) are parasites of birds.

cheyletiosis: a mange caused by infestation by species of Cheyletiella (Prostigmata: Cheyletidae), host-specialists that live on the epidermis of small to medium sized mammals: C. yasguri Smiley is associated with dogs, C. blakei Smiley infests cats, and rabbits are host to C. parasitivorax (Mégnin).  Infestations of pets and lab animals can be without symptom, but in severe cases pruritis, hair loss, and crustose lesions can develop.  Species of Cheyletiella are highly active mites, and their skin-like color and rapid scampering has given them their common name, walking dandruff. 

chigger: the parasitic larval stage of a member of the Trombiculoidea (Prostigmata, Parasitengona) that feed on the skin of vertebrates causing dermatitis (see trombidiosis) and some of which transmit scrub typhus.  Nymphs and adults feed on small arthropods and their eggs and are often brightly colored, and densely hairy (velvet mites).

Chilean predatory mite: the phytoseiid mite Phytoseiulus persimilis Athias-Henriot, a commercially available and extremely efficient predator of spider mites.  Also called persimilis or the predatory mite.

circumanal setae: in Mesostigmata, the three setae (postanal and pair of peranal) setae surrounding the anal opening.

circumcapitular furrow: the flexible articulation joining the capitulum (gnathosoma) to the body (idiosoma).

circumgastric scissure: (furrow) the flexible articulation that joins the notogaster to the ventral plate in brachypyline oribatid mites.

Claparède's organ: an osmoregulatory organ located between legs I-II in the prelarvae and larvae of many acariform mites (= urstigma, also urpores, bruststiele). The serially homologous genital papillae are present in nymphs and adults whose larvae have Claparède's organ (Oudeman's Rule). Tydeid mites may retain the urstigmata beyond the larval stage.  

clavate: with a terminal knob or swelling; club-shaped; globose; capitate.

claw: like - having a distal hook; resembling a claw.

clunal setae: in Mesostigmata, setae J5, which are usually the most posterior pair of median opisthonotal setae.

clunals: the 5th dorsocentral setae (DC5 = h1 or f3) in the Prichard & Baker System.  Also see below.

coalesced: united, grown together, as for example, the genital and anal regions of some prostigmatans.

cocoon: a silken sack spun by some acariform mites in which molting takes place.

collar traechae: obsolescent term used for the peritremes in spider mites and their relatives.

colliculate: having a pattern resembling fish scales; usually used for a raised, rounded and reticulate-like ornamentation on shields, especially in Mesostigmata.

comb claws: usually bipectinate or biserrate claws or empodia, as for example in teneriffiid mites (Prostigmata).

comb seta: pectinate setae on the palps of cheyletid mites (Prostigmata)

companion seta: a seta closely associated with a solenidion, sometimes sharing the same insertion.

condylophore: (Greek kondylos = knuckle + phor = to carry) - in Acariformes, a pair of internal sclerotized structures involved in the articulation of the empodial (e.g., Astigmata) and lateral claws.

connate: body parts or structures that are fused or united; in eriophyoid mites, the anterior sternal apodemes may be connate, forming a fused structure that makes up the sternum

conoid discs: two pairs of structures on the sucker plate of astigmatan deutonymphs (hypopi).

corniculus: (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.

costula: a longitudinal ridge or set of ridges on the prodorsum of some oribatid mites, similar to lamellae but without a projecting edge or cusp.  

coxa: the basal segment of the leg, articulating with (Parasitiformes) or fused to (Acariformes) the body wall.

coxal fields: the venter of acariform mites where the coxae have fused to the body wall covering the sternal region.

coxisternal plate: a sclerotized plate in the coxisternal region.

coxisternal seta: a seta in or between the coxisternal plates and numbered from coxa I-IV e.g., 1a-c, 2a-c, 3a-c, 4a-c

coxisternum: floor of the podosoma that serves to support the legs, composed of the fused coxae (epimera I-IV).

cribrum: the spiculate area posterior to and often lateral to the anal opening on the shield bearing the anal opening and circumanal setae in Mesostigmata.

crista: a crest-like or tooth-like ridge, especially a pair of such on the notogaster of some oppioid oribatid mites.

crista metopica: the often narrow prodorsal sclerite bearing 1-2 pairs of trichobothria in parasitengone mites.

Cryptostigmata: An obsolete term for the Oribatida. The name refers to the concealed (cryptic) stigmatal openings of the trachea, which are situated in the acetabula (sockets) of legs I and III. (Greek kryptos = hidden.)

cunaxid: a predatory mite in the family Cunaxidae (Prostigmata); sometimes, but not always, a snout mite; some species are bright red and have large raptorial palps, others are pale to brownish in color and have short palps, but both types usually have a distinctive neck between the capitulum and idiosoma.

cuneate: ending in a wedge-shaped process.

cuneiform: wedged-shaped, as in ancient writing systems that used wedge-shaped characters.

cuticular lobes: the pattern of minute, raised processes that ornament the plicate ridges in the cuticles of many mites.

cyclamenmite: Phytonemus (aka Steneotarsonemus) pallidus (Banks) a plant-parasitic tarsonemid mite.

deficient: in relation to setae, reduced from a presumed holotrichous number.

dendritic: branching like a tree or bush, aborescent.  

denticles: small tooth-like processes, e.g., on the subcapitula of ticks and many mesostigmatans.

denticulate: bearing small, sharp processes, e.g., the hypostome of ticks.

Dermanyssina: an alternative name for the hyporder Dermanyssiae, a lineage of Mesostigmata.

dermanyssoid: a member of the Dermanyssoidea (Mesostigmata).  Most dermanyssoids are parasitic on vertebrates, but some (e.g., species of Varroa, Tropilaelaps) are parasites of honeybees or other insects.  Members of the Hypoaspidinae (=Hypoaspididae) are primarily free-living predators including species useful in biocontrol in the genera Geolaelaps, Stratiolaelaps, and 'Hypoaspis'.

deutogyne: overwintering or aestivating form of eriophyoid mites; morphologically distinct from the normal or protogyne form.

deutonymph: (also deuteronymph) the second nymphal stage or instar.

deutosternal denticles: rows of small teeth-like projections (often irregular and sometimes reduced to a single tooth) running transversely across the deutosternal groove and sometimes onto the lateral faces of the subcapitulum.

deutosternal gutter: (also groove, hypognathal groove, subcapitular groove) the median longitudinal gutter running on the subcapitulum of parasitiform mites that receives the tritosternum.

deutosternum: the sternum of the second body segment (pedipalps); the basis capitulum in parasitiform mites.

diapause: a period of dormancy or metabolic slowdown in the life cycle of an organism, typically in response to unfavorable environmental conditions (e.g., extreme cold or heat). Diapause allows mites and other organisms to survive adverse conditions by temporarily halting development or reproduction.

diarthric: a subcapitulum with a more or less transverse articulation that reaches the lateral margin at the base of the palp.

dichoid: a body appearing to be divided between legs II-III by a flexible sejugal furrow (Acariformes).

dichoidy: having the body articulated between legs II-III by a flexible sejugal (protero-hystersomatic) furrow (Acariformes). (See also trichoidy, ptychoidy, holoidy).

digitus fixus: see fixed digit.

disjugal plane: (furrow) the plane separating the ancestral prosoma and opisthosoma, usually not clearly present in mites and often confounded with the sejugal furrow.

distad: towards the free end of an appendage; the part of a leg or palp segment farthest from the body.

distal: towards the free end of an appendage.

divided dorsal shield: in Mesostigmata, adult mites have two usually subequal dorsal shields.

domatia: see acarodomatia.

dorsal: relating to the upper or back side; opposed to ventral.

dorsal hexagon: a fancied hexagonal area staked out by setal pairs j5, z5 and j6 in the podonotal region of many mesostigmatans; useful for orienting to setae to determine designations (see Lindquist-Evans system);  setae j3-5 may also form a hexagonal array.

dorsal lyrifissure: the dorsal lyrifissure posteriad the cheliceral seta in Mesostigmata.

dorsal seta: any seta on the dorsum; in the Eriophyoidea the scapular seta sc.

dorsal seta II: in the Eriophyoidea, the scapular seta sc.

dorsalseta I: in the Eriophyoidea, the external vertical seta ve.

dorso-sejugal suture: (also dorsosejugal groove) a suture marking the fusion of the prodorsum and notogaster; the anterior portion of the circumgastric scissure.  NB - this term is often misapplied to a flexible juncture or furrow.

dorsocentrals: Dorsocentral (DC or D) opisthosomal setae of spider mites in Pritchard & Baker (1955.  A revision of the spider mite family Tetranychidae.  Mem. Pac. Coast Entomol. Soc. 2: 1-472.).  DC1 = c1; DC2 = d1; DC3 = e1; DC4 = f1; DC5 = h1 in the Grandjean system.

dorsolaterals: Dorsolateral (L) opisthosomal setae of spider mites in Pritchard & Baker (1955.  A revision of the spider mite family Tetranychidae.  Mem. Pac. Coast Entomol. Soc. 2: 1-472.).  L1 = c2; L2 = d2; L3 = e2; L4 = f2 in the Grandjean system.

dorsum: the upper or back side; opposed to venter.

duplex setae: a pair of setae or a seta and a solenidion sharing the same insertion.

earth mite: a member of the Penthaleidae (Prostigmata: Eupodoidea), including major plant pests in the redlegged earth mite (Halotydeus) and the blue pea-winter grain mite (Penthaleus) genera, or related families with red legs and black to  dark green bodies.  In reality, the entire cuticle is reddish, but the dark body contents obscure the body color.

edentate: with out teeth; usually referring to chelicerae.

elattostase: (adj. elattostatic) one of the abnormal stases recognized by Grandjean where the mouthparts are not functional but the legs are, e.g., prelarvae of some Anystina and Nanorchestidae; the deutonymph in Astigmata.

elbowed: bent as in the arm at the elbow; geniculate.

Eleutherengona: (also Eleutherengonida, Eleutherengonina, Eleutherengonides) an infraorderwithin the Prostigmata consisting of the two hyporders Raphignathina and Heterostigmata.  Eleutherengona includes many of the most important plant-parasitic mites, e.g., spider mites, broad mite, cyclamen mite.

emergent: rising above, projecting, as in the peritremes of some Prostigmata which range from small bumps to elongate processes.

empodium: (pl. empodia) an unpaired structure arising between the tarsal claws, ranging from pad-like to claw-like and often bearing structures such as tenent hairs, dense setulae, or taking the form of a featherclaw (Eriophyoidea)..

Endeostigmata: a paraphyletic assemblage of early derivative sarcoptiform mites that has often been misplaced in the Prostigmata.  Ten families are currently recognized, including the widespread and common Nanorchestidae, Bimichaeliidae, Alicorhagiidae, and Terpnacaridae.  Most endeostigmatans are fungivores, algivores or feed on minute, soft-bodied invertebrates such as nematodes.

endeostigmatan: a member of the Endeostigmata; characteristic of or belonging to the Endeostigmata.

endeostigmatic: adjectival form of Endeostigmata. 

endeostigmatid: incorrectly formed, but commonly used, adjectival form of Endeostigmata.

endogynal processes: (also endogynial, perigynum) processes (sclerites); sclerotized structures lying under the genital shield, especially in early derivative Mesostigmata such as Parasitidae, Zerconidae and Trigynaspida (see vaginal sclerites).  These structures may be simple or highly elaborated.

endogynum: the endogynal processes; internal sclerotized genitalic characters.

endopodal shield: (elements) narrow, strap-like, angular to subtriangular sclerites produced around the bases of the coxae in Mesostigmata; the anterior endopodal shields (I, II) are often fused to the sternal shield.

engorged: swollen from feeding as in a tick or chigger.

entire: a shield or sclerite with a continuous margin without incisions.

epiandrum: a large, concave intercoxal region containing the male genital opening in the Holothyrida.

epicoxal seta: a minute, usually peg-like seta on the dorsal face of the palpcoxa (ep) or coxae of legs I (ep1) in some acariform mites.

epigynal: (also epigynial) of or relating to the female genital opening or a shield protecting it.

epigynum: (also epigynium) the external genital opening in the female; also used for the ovipore in Dermanyssina (which have a secondary female genital system).

epimere: (pl. epimera) (also epimeron) in oribatid mites, a sclerotized coxal field; in Astigmata, anterior coxal apodeme.

epimerite: in Astigmata, the posterior coxal apodeme.

epimorphic: possessing the definitive number of segments on hatching.  Opposed to anamorphic.

epistome: in acarology this usually refers to the gnathotectum of the Mesostigmata.  

epsilon: (e) designation for the famulus on the tarsi of some acariform mites.

ereynetal organ: a solenidion in a pouch-like recess in the tibiae of certain ereynetid mites (Prostigmata: Ereynetidae).

erineum: (pl. erinea) the open, fleece-like galls produced by some eriophyoid mites (Prostigmata: Eriophyoidea)

erinose mite: prostigmatans in the Eriophyoidea that produce galls that resemble dense aggregations of hairs (resembling fleece).

eriophyid: (eriophyoid) of or relating to a member of the family Eriophyidae (superfamily Eriophyoidea) which contains minute, worm-like and quadripod mites that cause galls, erinea, and other damage to plants.

euanal setae: setae borne on the anal valve (Parasitiformes).

eugenital setae: setae originating within the genital vestibule (Acariformes).

eupathidion: (pl. eupathidia) an optically active but hollow seta with a pore at its tip and found on the palptarsus or leg I tarsus of many acariform mites; probably a chemoreceptor; designation = zeta (Ζ).  (Also acanthoides).

euryxenic: (-ous) using a broad range (e.g., of habitats or hosts); a host or habitat (etc.) generalist.

Evans leg chaetotactic system: in Mesostigmata, the nomenclature for the setation of legs segments derived by GO Evans.  In essence, the leg is visualized oriented dorso-ventrally and at a right angle to the body midline, such that four aspects are present: dorsal, ventral, anterior lateral, and posterior lateral.  Setae are designated in rows for their anterior (ad) or posterior dorsal (pd), ventral (av, pv) or lateral (al, pl) aspects and numbered from distal to basal.  For example, a segment with 2 rows of 3 dorsal setae would have three anterior dorsal (ad1-3) and three posterior dorsal (pd1-3) setae.  Evans devised a similar system for the palps.

excrescence: (1) a brush-like, dendritic or otherwise elaborated processes produced from openings in the movable digit in trigynaspid and some microgyniine Mesostigmata; (2) an encrusted covering or outgrowth-like structure. 

exopodal shield: usually narrow, strap-like sclerites, sometimes broader, produced around the lateral bases of the coxae in Mesostigmata; sometimes fused to the peritrematal shield.

external malae: the corniculi.

externalhypostomal(also hypostomatic) setae: (also external hypostomatic setae) usually the most lateral (h2) of the three pairs of hypostomatic setae in the Mesostigmata; present in the larva.

externalscapular seta: prodorsal seta sce (also se or s2) in Acariformes. 

externalvertical seta: prodorsal seta ve (also se or s2) in Acariformes.

exuviae: (pl. exuviae) the outer layer of skin not recycled during a molt; empty exuviae are a sign of previous mite development on a substrate; some oribatid mites retain the dorsal notogastral portion of exuviae as a pagoda-like pile of scalps.  (NB: the use of 'exuvia' as a singular makes no more sense than 'cloth' for 'clothes'.)

falcate: curved and more or less sickle-shaped.

fallacis: the phytoseiid mite Neoseiulus (also Amblyseius) fallacis (Garman), a generalist predator used in a variety of cropping systems.

false spider mite: a member of the family Tenuipalpidae (Prostigmata), e.g., species of Brevipalpus.  False spider mites share the stylophore and whip-like stylets of spider mites, but are usually protected by sclerotized plates and are often dorso-ventrally flattened, resulting in another common name: flat mites.

famulus: a hollow and optically active seta-like structure located near the base of the dorsum of tarsus I in acariform mites; designation = e (epsilon).

fastigals: (ft) the most basal pair of dorsal tarsal setae on the tarsi of acariform mites (see whorl).

fatal flatulence: possibly apocryphal ability of some Parasitengona to expel a paralyzing gas from their anal opening when hunting springtails. 

feather mite: a member of the Astigmata that lives on bird feathers.

featherclaw: the highly divided bipectinate empodial claw found in the Eriophyoidea.

femur: (pl. femora) major leg segment between trochanter and genu; often subdivided into a basifemur and a telofemur.

femurogenu: femurogenua (pl.) refers to the segment of a mite's leg formed by the fusion of the femur and the genu (two leg segments).

festoons: the ornamentation in some ticks that resembles a series of loops around the margin of the body.

filiform: thread-like; long and narrow.

fissure: a narrow slit of soft cuticle or line of juncture in a sclerotized shield or leg segment.

fixed digit: the distal extension of the middle article of the chelicera; usually bearing teeth and a distal hook and opposed to the movable digit in chelate-dentate forms, but often regressed; in Mesostigmata the fixed digit may bear the pilus dentilis.

flatmite: a dorso-ventrally flattened member of the family Tenuipalpidae (Prostigmata), e.g., species of Brevipalpus.  Flat mites share the stylophore and whip-like stylets of spider mites, but are usually protected by sclerotized plates; also called false spider mites.

foliose: leaf-like; usually describing flattened, oval to rectangular setae with or without other ornamentation.

fossa: (pl. fossae) a pit or recessed area in the integument (also see pedofossa).

fova pedales: (pl. = fovae pedales) a pedofossa, a pit in the cuticle into which the legs can be withdrawn in some Mesostigmata, especially Uropodidae.

foveate: ornamented with large circular depressions.

foveolate: ornamented with small circular depressions; approaching punctate.

fowlmite: a member of the Dermanyssoidea (Mesostigmata) parasitic on birds, especially the poultry red mite (Dermanyssus gallinae (de Geer)), the northern fowl mite (aka Starling mite - Ornithonyssus sylviarum (C&F)), or the tropical fowl mite (Ornithonyssus bursa (Berlese)).  

fragmented: broken up, composed of several discrete parts rather than of a single unit.

frontal seta: in the Eriophyoidea, the unpaired, median internal vertical seta vi.

fundamental: (as in fundamental chaetome) a seta or other structure present in the larval stage.

gabelzhan: in Mesostigmata, the offset and usually most distal tooth on the fixed digit (German: Gabel [fork tine] and zahn [tooth].

gall mite: a species of Eriophyoidea that produces galls on plants.

gaster: the idiosomal venter.

geniculate: with an elbow- or knee-like bend.

genital acetabulum: (pl. acetabula) an invagination containing the genitalia; also sometimes used for the genital papillae, especially in the Hydrachnida.

genital aperture: the genital opening or acetabulum.

genital disc: see genital papillae.

genital lamella: a small process that may cover the base of the tritosternum in male Parasitidae (Mesostigmata)

genital orifice: the male genital opening; in Mesostigmata the genital orifice is usually subcircular, located in the intercoxal region (often at the base of the tritosternum), and has 1-2 valves.

genital papillae:  1-3 pairs of extrusible finger-like to button-like projections, usually retracted into in the genital vestibule of acariform mites; sometimes formed as sessile disks around the genital opening; thought to be osmoregulatory structures; modified or multiplied and dispersed over the body in many freshwater mites.  Genital papillae are absent in the larva, but may be added ontogenetically: protonymphs have one pair, deutonymphs two pairs, and tritonymphs (and adults) three pairs.  The tritonymphal pair of papillae is often lost.  The serially homologous Claparède's organ is usually present in the larvae (and prelarvae) of mites exhibiting genital papillae in nymphs and adults (Oudeman's Rule).

genital seta: a seta on a genital shield or valve; seta st5 in the Mesostigmata; the genitals g1-g2 in spider mites; in the Eriophyoidea, coxisternal seta 3a.

genital shield: a shield or shields covering the genital opening; in female mongynaspine Mesostigmata this shield is usually called the epigynal (epigynial) shield.  

genital sucker: see genital papillae.

genital valves: sclerites covering the genital opening; usually referring to small sclerites (larger ones are usually called 'shields' or 'plates'.

genital vestibule: the  ventral chamber containing the genital papillae and genital opening and closed by a pair of genital valves.

genitals: 1st genitals or anteromedial genitals (= g1) and 2nd genitals or posterolateral genitals (= g2) in the Pritchard & Baker System.

genitiventral shield: (= opisthogenital shield) in Mesostigmata, an epigynal shield that extends back over the ventral region but is separate from the anal shield, e.g., in Pseudoparasitus spp. (Laelapidae), and leaves any metapodal elements free.

genu: (pl. genua) (= patella) the 4th leg segment, between the femur and tibia.

gestalt: the overall form or concept; the whole animal, habitus; usually used to describe how one knows the identity of a mite even if they can't specify the diagnostic characters (German = ge'-shtailt).

gland: usually referring to a glandular opening in the cuticle such as the lateral opisthonotal glands in the Sarcoptiformes or the idionotal glands in the Mesostigmata (see gdj etc. above), including hypertrophied openings that produce defensive secretions.

glandularium: (pl. glandularia) the gland complex in water mites (Hydracarina); on the surface these consist of the gland openings and associated trigger hairs, often carried on a small sclerite.

globose: spherical.

gnathosoma: (= capitulum) the anteriormost part of a mite or ricinuleid, composed of the cheliceral and pedipalpal segments and separated from the body (idiosoma) by a ring of soft cuticle.

gnathosomal capsule: a fusion of the gnathosomal elements (chelicerae and subcapitulum) into a single structure, as seen in protigmatans such as Heterostigmata, Myobiidae, and Cheyletoidea (also tegmen).

gnathotectum: (= 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.

Grandjean system: the primary system for designation of hysterosomal setae used in the Acariformes.  Hypothesized segments (anterior to posterior) are C, D, E, F, H, PS (pseudanal), AD (adanal), AN (anal) and PA (peranal) (see anamorphosis).  'G' is not used, to avoid confusion with the genital segment, which is treated separately.  Setae are designated from the midline to the sides from 1-x, e.g., c1, c2, c3, c4 (also cp).

habitus: a view of the entire animal.

hair: usually referring to a seta; considered an imprecise and misleading term for seta.

Haller's organ: the array of sensory setae in a pit and depression on tarsus I of ticks; similar structures on holothyrans and some mesostigmatans.

hemispherical: roughly half a sphere; used to describe the habitus of some mites.

heterodactyly: having claws of different size or form.

heteromorphic: having different morphological forms; referring either to different forms within a particular life stage (e.g., normal and heteromorphic deutonymphs in some Mesostigmata; protogynes vs. deutogynes in Eriophyoidea; heteromorphic vs. homeomorphic males in the Astigmata) or to a developmental stage that differs radically from other stages (e.g., the heteromorphic deutonymph or hypopus in the Astigmata).

hexapod: with three pairs of legs (i.e. 6 legs), as in the larvae of mites or the larviform stages of others.

holodorsal 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).

hologastric shield: in Mesostigmata, a shield that covers the genital, ventral and anal regions; a ventrianal shield that incorporates the metapodal elements and is fused to the epigynal shield. 

holoid: lacking flexible cuticle between legs II-III.

holotrichous : adjectival form of holotrichy.

holotrichy : having the complete complement of setae thought to have been present in the ancestor of a group (Greek holos = entire + trich = hair);  opposed to neotrichy (new hairs) or hypertichy (too many hairs).

holoventral shield : in Mesostigmata, a shield that covers the entire venter of a male, including the intercoxal region (where it bears the genital aperture), the ventral region and the anal region.

honeybee tracheal mite : Acarapis woodi (Rennie) a tarsonemid mite that lives parasitically in the tracheae of honeybees and is associated with the development of Isle of Wight Disease.  Other species of Acarapis live externally on bees.

hook: (as in cheliceral hook) the distal hook-like tips of chelicerae in the Mesostigmata, as opposed to cheliceral teeth.

horn : any horn-like process, but in Mesostigmata often referring to a posterior process of the idiosoma.

humeral process: (projection) any fixed projection in the humeral region; sometimes confused with pteromorphs in oribatid mites; lateral raised areas of the idiosoma associated with the peritreme in some uropodids (Mesostigmata).

humeral seta : a seta in the humeral ('shoulder') region, often projecting at a more or less right angle to the body; usually seta r3 (rarely r4) in Mesostigmata and H or c3 (rarely c4 = cp) in Acariformes.

hyaline : transparent, membranous, e.g., a hyaline sheath.

hyperphoresy : a phoretic mite transported on another phoretic organism.

hypertrichous : having more than the number of setae normally found in a group (Greek hyper = above + trich = hair); a more neutral term than neotrichy, which implies that the additional hairs have been added during the evolution of the group.  (see also hypotrichous, holotrichous).

hypertrichy : the condition of being hypertrichous.  

hypognathal denticles: (deutosternal denticles) rows of small teeth-like projections (often irregular and sometimes reduced to a single tooth) running transversely across the deutosternal groove and sometimes onto the lateral faces of the subcapitulum.

hypognathal groove: (also hypognathal gutter, subcapitular groove, deutosternal groove or gutter) the median longitudinal gutter running on the subcapitulum of parasitiform mites that receives the tritosternum.

hypoplasia: a condition in which a tissue or organ is underdeveloped or incompletely developed. The term is often used to describe the condition of plants in response to mite feeding, where feeding damage results in stunted or malformed growth.

hypopode : see hypopus

hypopus: (pl. hypopi) (also hypopode) the heteromorphic deutonymph produced by many astigmatans, usually as a stage that is phoretic on insects and having a large ventral sucker plate.  Hypopi lack functional mouthparts and the capitulum is reduced to a small nub bearing a pair of processes, but some appear to feed by absorbing fluids through their cuticles.

hypostomal denticles: (teeth, retrorse teeth) the backwardly directed tooth-like projections on the elongate hypostome of ticks that are used to anchor the capitulum to skin while feeding.

hypostomal setae : (also hypostomatic setae) the three pairs of setae on the hypostome of mesostigmatans; the anterior (h1) and external hypostomal (h2) setae are present in the larva; the internal hypostomal seta (h3) is added in the protonymph.  These setae are arranged more or less longitudinally in most uropodines and tend to be in a triangular array in non-uropodine Mesostigmata.

hypostome : the anterior part of the subcapitulum (Gr hypos = under + stoma = mouth) in parasitiform mites that bears the corniculi and hypostomal setae; presumably the remnant of the palpcoxal endites.  In the Eriophyoidea, a synonym for the capitulum (infracapitulum, rostrum, gnathosoma).

hypotrichous : having fewer than the number of setae normally found in a group (Gr hypo = below + trich = hair), e.g., phytoseiid mites (Mesostigmata) have 20 or fewer pairs of dorsal setae.  (see also hypertrichous, holotrichous).

hysterosoma : idiosoma behind the sejugal furrow (plane) between legs II-III; opposed to the proterosoma.

hysterosomal: (hysterosomal) adjectival form of hysterosoma.  

hysterosomatic: (hysterosomatic) adjectival form of hysterosoma.

idionotal : on the dorsum of the body (idiosoma).

idionymic : structures or stages that differ in discontinuous surface characters.

idiosoma : (Greek idios = distinct + soma = body) the main body tagma of mites, containing the opisthosoma and part of the prosoma.  

idiosomal: (idiosomatic) adjectival form of idiosoma.

idiosomatic: (idiosomal) adjectival form of idiosoma.

imagochrysalis : the tritonymphal stage in the Parasitengona; a calyptostatic cuticle formed within the deutonymphal cuticle in which the adult stage develops.

incised : cut into, e.g., a dorsal shield composed of podonotal and opisthonotal  shields fused medially but free laterally.

infracapitulum : the capitulum or gnathosoma (sometimes used to indicate only the subcapitulum).

infundibulum : a depression in the cuticle associated with the opening of a gland; also a swelling of the tubulus under the solenostome in laelapid type sperm access systems.

inguinal pore plate : in gamasine Mesostigmata, a pair of small sclerites in the region of the posterior corners of the genital shield and parapodals IV that bears the inguinal glands gv2.

inner infracapitular stylets: (= auxilary stylets) a pair of stylets of uncertain origin in the bundle of 7-9 stylets in the Eriophyoidea.

inner sacrals : setae DC4 (= f1) in the Pritchard & Baker System

inquiline: an animal that lives habitually in the living space of another species; e.g., an insect that lays its eggs in a gall produced by another insect.

instar: (Latin = form) an immature mite or other arthropod between molts (or from apolysis to apolysis for some authors), or between egg hatching and the first molt.  Mites mostly have determinate growth and do not molt after reaching the adult stage; therefore, the adult is not considered an instar.

intercalary sclerite : in Mesostigmata, a small sclerite between the basitarsus and telotarsus on leg IV.  May bear setae av4 and pv4.

intercoxal : between the coxae.  In Parasitiformes, a sternal region lies between the bases of the legs and usually contains one or more sternal shields and at least the anterior portion of the genital shield.  An intercoxal shield in male Mesostigmata is often called the sternogenital or sternitogenital shield because it bears the genital opening.  In Acariformes, no sternal region is present and the coxae of the legs are fused to the venter and usually meet medially; genital openings are usually postcoxal, but may intrude between the fused coxal bases in Astigmatina.

internal malae : a pair of fleshy, fimbriated processes mediad the corniculi and acting as part of a filtration system in fluid-feeding mesostigmatans; these are expanded in some groups (e.g., in many Veigaiidae they look like handlebar moustaches).  

internal scapular seta : prodorsal seta sci (also si, sc1 or s1) in Acariformes.

internal vertical seta : prodorsal seta vi (also v1) in Acariformes

internal hypostomal setae : (also internal hypostomatic setae) usually the most median (h3) of the three pairs of hypostomatic setae in the Mesostigmata; added in the protonymph.

jugularia: (singular jugularium) in Mesostigmata, a pair of presternal shields bearing setae st1 and /or pores stp1.  If fused, this shield is often called a tetartosternum.

krobylophore : cuticular, duct-like structure in ticks.

labiogenal articulation : a flexible juncture on the venter of the subcapitulum that allows the paired anterior sections (genae) to articulate with the base (mentum); see anarthric, stenarthric, diarthric.

labium : the sternal plate of the third body segment (tritosternum); the term is not generally used in acarology (see mentum).

labrum : an unpaired membranous and denticulate process thought to be an extension of the dorsal pharyngeal wall that lies above and between the chelicerae.

lacinia : in Mesostigmata, one of the processes borne on the stalk of the tritosternum.  

laelapid type of sperm access system : in most dermanyssine Mesostigmata (except Phytoseioidea, see phytoseiid type), a secondary sperm receiving and processing system consisting of a pair of external solenostomes (the sperm induction pores) that open (usually in the posterior intercoxal region or on the basal segments of legs III-IV) into a small swollen area (the infundibulum) that is produced into a long duct (tubulus).  The tubuli may terminate indefinitely, in a nozzle-like structure, or join a median, sack-like sacculus via a pair of horn-like rami.  The tubulus enters the ramus via a valve.  The sacculus sits above the ovaries and empties via a short median sperm duct.

lamella: (pl. lamellae) a longitudinal projection on the prodorsum of many oribatid mites that protects legs I when they are retracted; lamellae usually arise near the base of the bothridia and terminate with a projecting lamellar seta (often on a free cusp).  Lamellae may be connected by a translamella.

lamellar cusp : the projecting anterior portion of some lamellae.

lanceolate : shaped like the head of a lance; suboval and coming to a point at one end.

larva : the second instar in acariform mites having a complete ontogenetic sequence, but the first instar in mites lacking a prelarva; hexapod (unless adults have less than 6 legs, as in Eriophyoidea) and usually active; may be feeding or non-feeding.

laterad : to the side (do not use with the preposition 'to' since this is part of the meaning of the word) (Latin latus = side + ad = toward.  

lateral eyes : the 1-3 pairs of simple ocelli usually found on the lateral aspect of the prodorsum.

lateral opisthonotal glands: (also lateral opisthosomatic glands, lateral abdominal glands, or oil glands) in Sarcoptiformes, a pair of glands with large openings (solenostomes) on the opisthosoma that are often surrounded by a purple, red, brownish or yellow color if the cuticle is lightly sclerotized.

lateral seta : in the Eriophyoidea, opisthosomal seta c2.

lateral : referring to the side or away from the midline.

latigynal shields : (also latigynial shields) a pair of sclerites laterad the mesogynal shield in some female parasitiform mites that help protect the genital opening; usually bearing one or more pairs of setae and sometimes fused to other genital or ventral elements.  The single female genital shield in the Gamasina may represent a fusion of the latigynal and mesogynal shields.

lenticulus : an unpaired light receptive structure (often with a lens) at the median anterior margin of the notogaster of some oribatid mites.

levator tendon : the muscle that moves the movable digit of the chelicera; usually indistinct, in some Uropodidae (Mesostigmata) it has an ovoid sclerotized node that is used in identification.

Lindquist-Evans system: the system of setal signatures proposed by EE Lindquist & GO Evans (1965) and the dominant nomenclature used in the Mesostigmata in the more modern literature.  Dorsally, the setae are designated by minor (on the pronotum or podonotum) and major (on the opisthonotum) Arabic letters representing longitudinal rows (from the midline to the lateral margin, j-J, z-Z, s-S, r-R, and an additional UR or submarginal row posteriorly) and Arabic numbers designating transverse rows (of hypothesized segments) from 1-6 on the pronotum and 1-5 (or higher in the UR-series) on the opisthonotum.  (Origins: i=>j [Ger.] innen, inner]; z [Ger.] zwischen, between]; s [Ger.] seite, side]; r [Ger.] rand, margin; UR [Ger.] unterer rand, under margin.)  See also, modifications by Lindquist (1994) and Lindquist & Moraza.  Ventrally, idiosomal setae are treated as belonging to three regions: the sternal (intercoxal), the ventral, and the anal.  Three pairs of sternal setae are present in the larva (st1-3); the genital seta st5 is added in the protonymph; and the metasternal seta st4 is added in the deutonymph.  The 'metasternal' seta probably has more to do with the genital than the sternal region and is the only 'sternal' seta that sometimes is not expressed.  The ventral region has up to three longitudinal rows (JV, ZV, and rarely SV [Lv]) with 1-5 transverse row designations.  The anal region has a pair of paranal setae (pa) and an unpaired postanal seta (po).

linea: (pl. lineae) a line, a line-like ornamentation on a shield, usually caused by a ridge; used in species-level systematics of Macrocheles (Mesostigmata: Macrochelidae).

lyrifissure : a cuticular proprioreceptor (deformation sensing) structure; under light microscopy these structures may look like slits or compressed-T's in hardened cuticle, or a round pit (cupule) in soft cuticle.  In Mesostigmata, lyrifissures are often called 'pores' when they have not been differentiated from gland openings.

macronyssid : a member of the family of blood-feeding parasitic mites Macronyssidae, including the common bird and rodent parasites in the genus Ornithonyssus that often bite people.

macropyline : having separate adgenital and aggenital (adanal) plates and genital and anal shields such that most of the post-coxal venter is occupied by the two paired series of shields; usage usually reserved to traditional oribatid mites (see brachypyline).

macroseta : enlarged setae, usually longer and thicker that other setae, but sometimes merely thicker or differently formed than normal; important taxonomic characters on leg IV in the Phytoseiidae.  

major duct : in phytoseioid Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae),  a tubular duct of various lengths which runs from the solenostome to a valve-like region of the sperm access system called the atrium.

median : the midline of the body or towards the midline a comparison, e.g., 'the j-series is median to the z-series'.

mental tectum : a projection of the mentum on some oribatid mites with diarthric subcapitula.

mentum: (pl. menta) the basal section of the subcapitulum in oribatid mites with a labiogenal articulation; probably homologous with the labium of other arachnids.

mesogynal shield : (also mesogynial shield) an unpaired median sclerites in some female parasitiform mites that helps protect the genital opening; usually nude and sometimes fused to other genital or ventral elements.  The single female genital shield in the Gamasina may represent a fusion of the latigynal and mesogynal shields.

mesonotal scutellae: (also mesonatal plates, mesonoatal platelets) in Mesostigmata, usually paired sclerites between the podonotal and pygidial shield.  

mesonotal shield : a transverse sclerite covering the mesonotum; usually lying between a podonotal and a pygidial shield.

mesostigmatan : a member of the Mesostigmata; characteristic of or belonging to the Mesostigmata.

mesostigmatic : adjectival form of Mesostigmata.  

mesostigmatid : incorrectly formed, but commonly used, adjectival form of Mesostigmata; a mesostigmatan.

metapodal line : in uropodine Mesostigmata, a ridge running from the medial face of coxa IV postero-laterally through the metapodal region.

metapodal plates: (also metapodal platelets, metapodal sclerites) a complex of small sclerotized structures posterior to coxae IV that probably represent muscle insertions.  Metapodal plates may be circular, but more commonly are irregularly elongate, divided in two, and resemble a shakily drawn exclamation point.  May be absent or incorporated into a ventrianal or holoventral shield.

metapodal shields: (also metapodal plates, metapodal platelets, metapodal sclerites) in Mesostigmata, a pair (sometimes fused) of small sclerites posteriad coxae IV in the ventral region that probably reflect muscle attachments.

metasternal setae : in Mesostigmata, the intercoxal setae (designated st4 or MS) added in the deutonymph, often are borne on metasternal platelets, and sometimes on the sternal shield or in soft cuticle in the adult female; rarely absent.

metasternal shield: (also metasternal platelet) small, usually teardrop to subtriangular shields bearing the metasternal setae (st4); sometimes fused to the sternal shield or the endopodal shields.

microarthropod : a minute arthropod, typically used to refer to soil-inhabiting arthropods with bodies under some  arbitrary length (e.g., 1 cm, 5 mm).  

microtrichia: (pl. microtrichiae) small hair- or tooth-like processes, as for example in the postanal cribrum of Mesostigmata.

microtubercle : a minute tubercle or tooth-like process, e.g., on the annuli of Eriophyoidea.

middle article : the middle of the maximum of three segments of the chelicera; often the basal segment in Acariformes.

midline : a hypothetical line running down the middle of a bilateral animal.

minor duct : In mesostigmatans with the phytoseiid-type of sperm access system, a fine tube originating at the atrium and usually becoming indistinct distally.

monobasic: (=monotypic) a taxon based on a single representative, e.g., a genus with only one known species.

monogynaspine: (monogynaspid) representative of the mesostigmatan suborder Monogynaspida, characterized by having a single genital shield in the adult female that usually bears one pair of setae (st5) or may be nude.

monotypic: (=monobasic) a taxon based on a single representative or type, e.g., a genus with only one known species.

morphotype: a particular form or variant of an organism within a species, identified by distinct phenotypic characteristics such as body size, shape, or coloration. Examples include deutogyne and protogyne females in eriophyoid mites or homeomorphic and heteromorphic males in Astigmata.

moustache-like: having the appearance of a well developed handlebar moustache, as in the internal malae of most species of Veigaia (Mesostigmata).  

movable digit : the most distal article of the chelicera, the cheliceral apotele; usually bearing teeth and a distal hook and opposed to the fixed digit in chelate-dentate forms, but when the fixed digit is regressed, the movable digit may be saw-like, knife-like or needle-like to stylet-like.

mucro : a small spine or spur; in Mesostigmata, a spine-like process on the venter of the movable digit, e.g., in Proctolaelaps.

mucronate : coming to a point, with a distal mucro or spine.

naso : an unpaired, nose-like protrusion of the idiosomal in the rostral region that projects over the chelicerae in early derivative Acariformes and may bear a pair of setae (ro = vi) dorsally and some times a median eye(s) ventrally; possibly homologous to the rostral tectum.

neck: (neck-like) a narrow constricted region joining the capitulum to the idiosoma.

neospermy : in Mesostigmata, having the derived ribbon-like sperm characteristic of the Parasitidae and the Dermanyssina.

neotrichous: having setae not present in the ancestral condition, 'new setae'; often a highly subjective assessment.

northern fowlmite: (aka Starling mite)  Ornithonyssus sylviarum (C&F): Mesostigmata, Dermanyssoidea, Macronyssidae.

notch: a subrectagular to v-shape incision or similar form on the margin of a sclerite.

notogaster: the dorsal hysterosoma, or in a more specific sense, the shield covering the dorso-lateral aspects of the hysterosoma in many oribatid mites.

notogastral: referring to the notogaster. [ Back to Top]

Notostigmata: an obsolete term for the Opilioacarida (also Opilioacariformes) referring to their possession of dorsolateral stigmatal openings.

notum: the dorsal idiosoma.

nr.: near, for uncertain species designations (e.g., Cosmolaelaps nr vacua (Michael)), meaning 'similar to', and implying that the specimen referred to may represent a new species (see cf., sp. nr., and aff.).

nymphochrysalis: the protonymphal stage in the Parasitengona; a calyptostatic cuticle formed within the larval cuticle in which the deutonymphal stage develops.

nymphophan organs: see genital papillae.

ocellus: (pl. ocelli) a simple eye.  Mites with eyes usually have one or two pairs of lateral ocelli, but some Opilioacarida have three pairs.  Additionally, some acariform mites have one or two median ocelli on the underside of the naso.

octotaxic system: the set of four pairs of porose or sacculate dermal glands on the notogaster of poronotic brachypyline oribatid mites.

oil glands: usually referring to the lateral opisthonotal glands of sarcoptiform mites.  These often have large openings (solenostomes) surrounded by a purple, red, brownish or yellow color if the cuticle is lightly sclerotized.

omega: (Ω) designation for solenidion the tarsus of acariform mites (Φ (phi) on the tibia, and Σ (sigma) on the genu).

opilioacaran: a member of the parasitiform order Opilioacarida.

Opilioacariformes: an obsolescent supraordinal term used for the Opilioacarida.

opisthogastric shield: in Mesostigmata, a shield that covers all of the venter behind legs IV including the anal region; a ventrianal shield that incorporates the metapodal and usually the exopodal elements (e.g., in Parasitidae).

opisthogenitalshield: (= genitiventral shield) in Mesostigmata, an epigynal shield that extends back over the ventral region but is separate from the anal shield, e.g., in Pseudoparasitus spp. (Laelapidae), and leaves any metapodal elements free.

opisthonotal: dorsal opisthosoma.

opisthonotal glands: see oil glands

opisthonotal shield: the posterior shield in mesostigmatans with divided dorsal shields.

opisthosoma: (= abdomen) the posterior body division in arachnids; usually not distinct in mites because of the fusion of the opisthosoma with part of the prosoma to form the idiosoma.

opisthosomal: (opisthosomatic) adjectival form of opisthosoma.

opisthosomal glands: see oil glands.  

opisthosomatic: (opisthosomal) adjectival form of opisthosoma.

oral stylet: the unpaired stylet in the bundle of stylets in the Eriophyoidea; Lindquist (1996) believes the oral stylet represents the labrum.

Oribatei: an obsolete name for the paraphyletic concept of Oribatida.

oribatidmites: are a member of the sarcoptiform suborder Oribatida (=Cryptostigmata, Oribatei); some academics consider the use of 'oribatid' as a noun to be low class, but others consider that attitude pedantic.

ostioles: small openings in a gall that allow mites to exit and disperse from the senescent gall at the end of the vegetative season.

outer infracapitular stylets: (= cheliceral guides) a pair of capitular processes that frame the cheliceral stylets in the Eriophyoidea.

oviparity: laying eggs.

ovipositor: an extrusible organ for laying eggs.  Female oribatids have a well developed ovipositor that ends in three finger-like projections.  Ovipositors are less well developed or absent in other mites.

ovoviviparity: laying eggs in an advanced state of development such that hatching occurs soon after laying or within the mother's body (see also viviparity).

pad-like: in Prostigmata, used to refer to empodia that do not have a distal hook (claw-like); when tenent hairs are present a 'pad-like' empodium may look more like a pincushion; in other Acari, usually a simple, pad-like empodium.

palp: (= 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.

palpalae: the 3 serrate setae on the palp of harpirhynchid mites (Prostigmata: Cheyletoidea).

palpcoxal seta: the pair of palpcoxal setae (pc or pcx), the most basal setae on the subcapitulum of mesostigmatans and not to be confused with the more anterior hypostomal setae.

palpfemur: palpfemora (pl.) refers to the femur segment of the palps in arachnids, including mites. This contrasts with leg femora, which are typically just referred to as femora.

palposoma: the reduced gnathosoma found on the heteromorphic deutonymphs (hypopi) of Astigmata.

palptarsal 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.

palptibial claw: a claw-like seta on the palptibia of some Prostigmata that forms a chelate structure with the palp tarsus, the palp thumbclaw complex.

pantelebasic rutellum: large rutellum with the apex toothed and meeting medially as in many Brachypylina.

para-anal: paranal

parabolic ventral suture: the converging ventral suture characteristic of adults of species of Eulohmannia (Oribatida).

paradactyli: (also pretarsal opercula) a pair of lateral, usually distally toothed structures on the pretarsus of many Mesostigmata; seemingly best developed in species that live in moist environments.  

paralaciniae: a pair of small processes on the anterior margin of the subcapitulum.

paranal 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.

parapodal shield: in Mesostigmata, a narrow sclerite posteriad coxa IV.

parasitine: representative of the Parasitidae (Mesostigmata: Monogynaspida: Parasitiae)

paraverticalsetae: in the Mesostigmata, the anteriormost pair of setae in the z-series, setae z1; usually on the anterolateral edge of the pronotum and inserted across a lyrifissure from the vertical setae j1.

paraxial: against the axis of the body (also adaxial), e.g., the inner face of the chelicera.

patrocinium: paralabral style in some Mesostigmata (e.g., Macrochelidae).  

peacockmite: (also ornate spider mite) a member of the family Tuckerellidae (Prostigmata).

pectinate: a seta or other process having comb-like teeth on one side (see bipectinate).

pedipalp: (= palp) the second pair of limbs in arachnids.

pedofossa: (pl. pedofossae) (= fossae pedales, fovae pedales) recesses into which the legs can be withdrawn.

pedotectum: (pl. pedotecta) a scale-like tectum arising around the insertion of legs I or II in some armored oribatid mites that covers the insertion of the leg and sometimes forms a protected space into which the legs can be withdrawn; not to be confused with the pedofossae in the venter of some uropodid mites (Mesostigmata) into which legs may be withdrawn.  (Also tectopedium).  

penicillate: resembling a brush or a bundle of long, slender processes.

peridium: (pl. peridia) a cavity filled with cuticular processes behind coxae IV in Allothyridae (Holothyrida) and some Mesostigmata; resembles the wire-brush tool into which spark-plugs can be inserted for cleaning.  Similar structures are found in the lateral opisthosomal cuticle of some sironoid Cyphophthalmi.

peripodomeric fissure: (peripodomeric suture) an area of soft cuticle that marks the juncture of the basitarsus and telotarsus or the basifemur and telofemur on the legs of Mesostigmata.  An intercalary sclerite may be present dorsally (Epicriidae) or ventrally on tarsus IV and bear 2 setae. 

peritrematal: (peritrematic) of or referring to the peritreme; adjectival form of peritreme.

peritrematic: (peritrematal) of or referring to the peritreme; adjectival form of peritreme.

peritreme: a groove or gutter on the surface connecting to a stigmatal opening.  In Mesostigmata the peritremes are lateral and run above the coxae of the legs and usually run to near the anterior margin of the idiosoma, but they may be very short or vestigial.  In Prostigmata peritremes are usually found on the anterior margin of the idiosoma, as short processes to either side of the capitulum (emergent peritremes), or as simple to complex lines or reticulations of short, connected chambers on the dorsal surface of the chelicerae or stylophore.

persimilis: the phytoseiid mite Phytoseiulus persimilis Athias-Henriot, a commercially available and extremely efficient predator of spider mites.  Also called the Chilean predatory mite or the predatory mite.

pharate: a mite or other arthropod between apolysis and ecdysis; the fully formed instar before it breaks through the previous cuticle.

pharynx: an organ posterior to the buccal opening that serves as a pump in fluid-feedings mites.  The form of the pharynx is an important taxonomic character in the Tarsonemidae.

phi: (Φ) designation for solenidion the tibia of acariform mites, (Ω (omega) on the tarsus; Σ (sigma) on the genu).

phoresy: a type of migration where mites board larger animals (usually insects or other arthropods) and cease or otherwise alter normal behaviors (e.g., feeding, reproduction, movement) until some cue elicits the departure from the animal and the resumption of normal behavior.  Phoresy usually results in the dispersal of populations, but may result in reaggregation, especially for mites using highly specialized habitats (e.g., pitcher plants and other phytotelmata).  Some mites hold on to their phoretic carriers with specialized structures (e.g., the anal pedicel in Uropodina; modified legs I in phoretomorphic Pygmephoridae; a specialized tooth on the chelicerae of many Macrocheles), but others simply use their feet or grip a seta with unmodified mouthparts.  Phoretic relationships my be highly host specific, very general, or anywhere in between, depending on the species.  In earlier work, phoresy was differentiated from parasitism by whether or not feeding occurred on the host.  However, recent work has shown that some phoretic mites may also feed on or otherwise harm their host.

phoretomorph: a heteromorphic phoretic stage; typically an adult morphology produced during dispersal by members of the Heterostigmatina, that differs from that of non-dispersing mites; usually includes well developed claws on legs ; any dispersing stage that differs in morphology from other stages.

physogastry: swelling of the opisthosoma to accommodate massive numbers of eggs or developing young.  Physogastry is common only in certain heterostigmtans including Pyemotidae, Pygmephoridae, and Podapolipidae.

phytoseiid: a member of the Phytoseiidae, including over 2000 described species, some of which are important biocontrol agents.  

phytoseiid-type sperm access system: In some Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae), a paired secondary sperm receiving and processing system consisting of an external solenostome (the sperm induction pore) that opens (usually near the base of coxae III-IV) into a tubular duct of various lengths (major duct) which runs to a valve-like region called the atrium.  A minor duct branches away from the atrium (presumably towards the ovaries, but the diameter seems to small to transfer sperm) via an embolus and the major duct opens into a collar-like structure called the calyx which empties into a vesicle where endospermatophores can often be seen.  Since this system is sclerotized, it is often visible on light microscope mounts and is often a very useful species-level character.

pilose: with a covering of hairs or hair-like processes.

pilus dentilis: (pl. pili dentilis) a seta-like or membranous sensory organ inserted ventrolaterally on the fixed digit of the chelicera of many Mesostigmata.

plastron-like: peritremes that are flattened and broad and serve as an incompressible plastron in mesostigmatans living in wet habitats.  

platytracheae: porose lamelliform pouch-like invaginations in the cuticle of some oribatid mites.

plicate: with a pattern of raised, narrowly aligned ridges like a fingerprint; used to describe the soft cuticle of many mites.

plications: the fingerprint-like pattern of raised ridges that often ornaments the soft cuticle of mites.

podo-opisthosomatic articulation: the well developed postpedal furrow in some oribatid mites (e.g., Elliptochthonius).  (See trichoidy.)

podocephalic canals: a pair of gutters to tubular ducts on the anterior margin of acariform mites, typically running from between the chelicerae posteriorly above the insertion of the legs; often confused with tracheae.

podomere: one of the segments of a leg or palp.

podonotal: relating to the dorsal podosoma, the region of the idiosoma over the legs.

podonotal shield: the anterior shield in mesostigmatans with divided dorsal shields.  

podonotum: the dorsal podosoma.

podosoma: region of the idiosoma bearing the legs (body segments III-VI); according to currently accepted theory, in acariform mites the dorsal portion of this division has regressed and only the leg bases are included.

podospermy: (also porospermy) a sperm transfer system where the spermatophore is deposited into a secondary pore-like opening.  In dermanyssine Mesostigmata, the sperm pore (solenostome) is usually located near the bases of legs III-IV, but may be elsewhere in the intercoxal region or on the coxa or trochanter of leg III or IV.

pore: 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.

porospermy: (also podospermy) a sperm transfer system where the spermatophore is deposited into a secondary pore-like opening.  In dermanyssine Mesostigmata, the sperm pore (solenostome) is usually located near the bases of legs III-IV, but may be elsewhere in the intercoxal region or on the coxa or trochanter of leg III or IV.

postanal seta: the unpaired median seta inserted posterior to the anal opening in the Mesostigmata; usually designated po or POS.

Postanals: (or posterior para-anals) setae h2 in the Pritchard & Baker System.

postcoxal: posterior to the coxae.  

postcoxal seta: the most basal seta (pc) on the subcapitulum of mesostigmatans.

posteriad: to the rear (do not use with the preposition 'to' since this is part of the meaning of the word), e.g., 'setae le are usually inserted posteriad setae ro'.

posterior: the back part of the body or towards that region in comparison, e.g., 'posterior to'.

posterior eye: the more posterior of a pair of lateral ocelli, usually different in form from the anterior eye and often lacking a distinct lens.

posterodorsalseta: a seta (pd 1-3) on the posterior dorsal surface of a leg or palp segment in the Mesostigmata.

posterolateralseta: a seta (pl 1-2) on the posterior lateral surface of a leg or palp segment in the Mesostigmata.

posteroventralseta: a seta (pv 1-3) on the posterior ventral surface of a leg or palp segment in the Mesostigmata.

postocular gland: (posocular pustule) a large lateral pustule directly behind the ocellus (and possibly homologous to the posterior eye) in Labidostommatidae (Prostigmata). 

postpedal furrow: (postpedal constriction, postpedal suture) a constriction or articulation of the idiosoma behind legs IV.  (See podo-opisthosomatic articulation).

poultry mite: a member of the Dermanyssoidea (Mesostigmata) parasitic on birds, especially the poultry (also chicken, pigeon) red mite (Dermanyssus gallinae (de Geer)), the northern fowl mite (aka Starling mite -Ornithonyssus sylviarum (C&F)), or the tropical fowl mite (Ornithonyssus bursa (Berlese)).

pregenital: in front of (anterior to) the genital opening.

Pregenitals: the aggential setae (= ag in the Grandjean system) in the Pritchard & Baker System.

prelarva: (also deutovum, prolarva) the first instar in acariform mites having a complete ontogenetic sequence, but absent in derived Prostigmata and Parasitiformes (except Opilioacarida); incompletely formed, without functional mouthparts, often retained within the egg shell or just extruding from it, and usually inactive; hexapod or apodous.

presternal platelets: small sclerotized plates anterior to the sternal shield and laterad or posteriad the base of the tritosternum in some Mesostigmata.

primilaterals: (pl) the most basal pair of ventral (ventrolateral) setae on the tarsi of acariform mites (see whorl). On the ventral tarsus behind the unguinals is the seta (s), followed by the anterolaterals (a), primiventrals (pv), and primilaterals (pl).

primiventrals: (pv) a pair of ventral setae between the anterolaterals and the primilaterals on the tarsi of acariform mites (see whorl).

Pritchard & Baker: A system of setal designations of spider mites in  Pritchard & Baker 1955 (A revision of the spider mite family Tetranychidae.  Mem. Pac. Coast Entomol. Soc. 2: 1-472.).  Dorsocentrals: D1 = c1; D2 = d1; D3 = e1; D4 = f1; D5 = h1; Dorsolaterals: L1 = c2; L2 = d2; L3 = e2; L4 = f2; Sublaterals: 1st sublaterals = c3; 2nd sublaterals = d3; 3rd sublaterals = e3; Humerals: H = c3;  also Inner sacrals (or DC4) = f1; Outer sacrals (or L4) = f2; Clunals (or DC5) = h1 or f3; Postanals (or posterior para-anals) = h2; Anterior para-anals = h3; Anals = ps1-3; 1st genitals (or anteromedial genitals) = g1; 2nd genitals (or posterolateral genitals)= g2;  Pregenitals = ag in the Grandjean system.

procurved: a curved suture or line of dehiscence that arches anteriorly; opposed to recurved.

prodorsal setae: the setae on the prodorsum of acariform mites.  Two competing chaetotactic systems are used for designations: the Rostral-lamellar and Vertical-scapular systems.  

prodorsal shield: a shield on the anterior dorsal surface of acariform mites.

prodorsum: the dorsal surface of the propodosoma.

progenital valves: the genital valves in acariform mites.

propodosoma: a subdivision of the podosoma bearing legs I-II.

prorals: (p) the most distal pair (at base of ambulacrum) of dorsal  setae on the tarsus of acariform mites (see whorl).

prosoma: (= cephalothorax) the anterior body region in arachnids; usually not distinct in mites.

prostigmatan: a member of the Prostigmata; characteristic of or belonging to the Prostigmata.

prostigmatic: adjectival form of Prostigmata.  

prostigmatid: incorrectly formed, but commonly used, adjectival form of Prostigmata; a prostigmatan.

protero-hysterosomatic articulation: (also protero-hyterosomatic furrow) a flexible juncture between legs II-III in some acariform mites.  (See dichoidy, trichoidy).

proterosoma: the body anterior to the sejugal plane (suture); complementary to the hysterosoma and only used in Acariformes.

protogyne: the normal feeding form, as opposed to the overwintering or aestivating form (deutogyne), of eriophyoid mites.

protonymph: the first nymphal stage or instar, usually octopod.

proximad: towards the base of a structure.  

proximal: towards the base of a structure; on a limb, towards the insertion on the body; sometimes also = approximate.

proximoventral hairs: the hair-like processes on the empodia of some spider mites; apparently represents a finely divided empodium, and not tenent hairs.

pseudanal: referring to the setae or other structures on segment PS in acariform mites.

pseudorutellar process: (also rutellum) (=pseudorutellum) in some Astigmata, e.g., feather mites.

pseudorutellum: a term used for the rutellum in Astigmatina.

pseudosternogynum: a pregenital shield in trigynaspid Mesostigmata that lacks pores (see sternogynum); probably homologous to the anterior genital shield in Holothyrida, but long interpreted as a sternal shield fragment.

pseudostigmatic organ: an obsolete term for the bothridial sensillum or trichobothrium, especially in oribatid mites.

pteromorph:  wing-like to shelf-like lateral extensions of the body in oribatid and tarsonemid mites.

ptychoidy: the ability of some oribatid mites to withdraw the legs between two body regions like a penknife being closed or a box being closed (hence box mites), and resulting in a seed-like appearance.  A derived form of dichoidy.

pubescent: covered with fine hairs; mossy.  

pulvillus: a membranous, pad-like structure associated with the claws in Mesostigmata. 

punctate: usually referring to ornamentation on shields resembling a dense array of needle punctures; with a granular appearance.

pusticulate: ornamented with small mound-like structures; covered with pustules.

pustule: a raised mound-like structure.

pygidial shield: (pygidial sclerite) in Mesostigmata, a shield at the back end of the idiosoma.

quadrigynaspine: (quadrigynaspid) representative of the Holothyrida or some Trigynaspida (Mesostigmata), characterized by having 4 genital shields in the adult female.

quiescent: at rest, usually referring to an inactive developmental stage, e.g., the inactive immatures of acariform mites during the intermolt period.

rake-like: a limb with more or less parallel projecting setae or spines resembling the tines of a rake.

ramus: a branch of a structure; also the horn-like region of the laelapid-type sperm access system where the tubulus annulatus enters the sacculus foemineus.

raptorial: (Latin raptor = robber) modified for capturing prey; predatory.  The pedipalps (e.g., many Cunaxidae) or legs I may be raptorial in mites.

receptaculum seminis: a swelling in the sperm duct of mesostigmatans with the laelapid-type of sperm access system.

recurved: a curved suture or line of dehiscence that arches posteriorly; opposed to procurved.

red mite: common name of a variety of mites with red cuticle (from carotene) such as the red spider mites (Prostigmata, Tetranychoidea) or that turn red on blood feeding such as the poultry red mite (Mesostigmata, Dermanyssidae).  

red velvet mite: the nymphal or adult stage of a terrestrial member of the Parasitengona (Prostigmata) that feed on small arthropods and their eggs.  Larval stages of one superfamily (Trombiculoidea) are the annoying chiggers.

reflexed: recurved, curved back on, as in the peritremes of Macrochelidae (Mesostigmata).

regressed: reduce from normal as, for example, the capitulum of astigmatan deutonymphs or the fixed digit of the chelicerae in varroa.

reticulate: 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.

retrorse teeth: (also hypostomal denticles or teeth) the backwardly directed tooth-like projections on the elongate hypostome of ticks that are used to anchor the capitulum to skin while feeding.

rhagidial organs: recumbent solenidia in shallow depressions on the distal segments of legs I-II in Eupodoidea (Prostigmata).

rostral gutter: the cheliceral sheath in the Eriophyoidea.

rostral seta: the anteriormost pair of prodorsal setae or an unpaired median seta (Nematalycoidea) in the Acariformes; when a naso is present, it often carries the rostral setae; various designations: ro,  vi, v1.

rostral tectum: (also rostrum) a prodorsal tectum that projects over at least the base of the chelicerae in acariform mites, often covering most of the capitulum; possibly representing a sclerotized naso; not to be confuse with the basis capitulum of parasitiform mites.

Rostral-lamellar system: a system of designations for the prodorsal setae in Acariformes based on Grandjean's system as applied to the Oribatida. These setae are not added ontogenetically; therefore, homologies are based on position and subject to various interpretations.  Each pair of setae may represent one of the 6 presumed prosomal segments; however, Grandjean believed that the dorsal podosoma and their setae were lost in acariform mites, in which case the prodorsal setae would derive from only cheliceral and pedipalpal segments.  The designations are: rostral (ro), lamellar (le), bothridial (bo), anterior exobothridial (exa, also xa), interlamellar (in), and posterior exobothridial (exp, also xp).  When present, setae bo are usually expressed as trichobothria (except in Nematalycoidea, Astigmata, some Oribatida, and many Prostigmata), and setae ro or le are sometimes trichobothrial).  In Endeostigmata, the Vertical-scapular system is more commonly used (vi, ve, sci, sce, in, exp, respectively).  Prodorsal setae exp, in or both are often lost.  In the Prostigmata, the prodorsal setae are represented at their maximum by the interior and exterior vertical (vi, also v1; ve, also v2) and internal and external scapular setae (sci, also s1; sce, also s2) (a possible exception exists in Pilorhagidia which has 5 pairs).  In Astigmata, the traditional designations follow those used in the Prostigmata; however, the purported internal scapular setae (sci or si) actually are in.

rostrum: In the Oribatida, the anteriormost dorsal portion of the idiosoma, especially when it projects over the bases of the chelicerae (see naso) (Latin rostrum = beak).  In the Prostigmata, the subcapitulum or the gnathosomal capsule in the Cheyletoidea or the capitulum (palps, subcapitulum, cheliceral stylets, cheliceral sheath, etc.) in the Eriophyoidea.

russeting: a type of damage on the surface of plants, often caused by plant-feeding pests, including mites. Russeting manifests in russet-colored (brownish) patches that are rougher than healthy skin on leaves or fruit.

rust mite: leaf vagrant forms of the Eriophyoidea whose feeding causes a russet coloration on leaves.

rutellum: (pl. rutella) In Sarcoptiformes, the hypertrophied setae on the hypostome, often toothed; not to be confused with a corniculus (although possibly a homologue).  In Astigmata, the rutellum may be referred to as a pseudorutellum, although it is the same structure.  Various forms of rutella are recognized, including the atelebasic and pantelebasic.

saccule: invaginated porose organs resembling small sacks and opening to the surface by a small pore (see octotaxic system).

sacculus foemineus: the sack-like structure (often with paired arms or swellings) in mesostigmatans with laelapid-type sperm access systems where the tubulus annulatus enters and the sperm duct originates.

sacculus vestibulus: the cavity in the acetabulum of the coxa or elsewhere in mesostigmatans with laelapid-type sperm access systems where the tubulus annulatus originates.

salivary stylus: (pl. styli) (also stylet) tube-like external ducts protected by the corniculi in Mesostigmata; usually dorsal to the corniculi and difficult to see and sometimes sitting in grooves in the corniculi.

scabellum: in Uropodina, a platform-like structure on the underside of the vertex that receives the withdrawn legs I.

scalps: notogastral portions of exuviae retained by some oribatid mites, often as a pagoda-like pile of larval through tritonymphal exuviae, although one or more of these may fall off during handling of specimens.  Scalp is also used to indicate the macerated cuticle of a mite that has been cleared and mounted on a microscope slide.

scapular seta: 2 pairs of setae (sci, sce) on the prodorsum of Prostigmata, often inserted on either side of the eyes; see Vertical-scapular system.

schizodorsal shield: in Mesostigmata, a holodorsal shield that incised laterally at about the midpoint or podonotal and opisthonotal shields that are fused only medially.

schizogastry: splitting of the cuticle to form a temporary opening to eliminate nitrogenous wastes (guanine) said to occur in some Parasitengona.

scissure: a band of unsclerotized cuticle between two plates; an elongate articulation.  NB - suture (an inflexible juncture) is often used inappropriately for what would be better termed a scissure.

sclerite: A component section of an exoskeleton; a plate forming the skeleton of an arthropod.

scleronoduli: 3-4 light refractile structures, sometimes comma-shaped, in the podonotal region of many Rhodacaroidea and the genus Protogamasellus (Ascidae) in the Mesostigmata.  

scutacarid: a member of the heterostigmatan family Scutacaridae (Prostigmata), sometimes called turtle mites.

scutella: (pl scutellae) small shields or platelets.

scutum: (pl. scuta) the podonotal shield in ticks (Ixodida).

segmentation: in mites distinct external segments have been lost but remnants of segmentation may be represented by hysterosomal folds or transverse arrays of setae and other cuticular sense organs.  In theory, all chelicerates have a prosoma composed of 6 segments (cheliceral, pedipalpal, and four leg-bearing segments = body segments I-VI).  Ventrally the positions of the prosomal segments can be identified by the insertions of their appendages, but dorsally they are obscured.  The opisthosoma is thought to comprise an additional 12-13 segments (body segments VII-XVIII or XIX), but appears to be somewhat to much reduced in most mites, except possibly Opilioacarida.  In early derivative Acariformes (e.g., many Endeostigmata), hysterosomal folds are thought to represent segmentation and in the Grandjean system are designated (from the sejugal furrow to the anus): C, D, E, F, H, PS AD, AN, PA.  There is disagreement in the literature over the origin of 'segments' C and D.  Adherents of Grandjean consider them to be opisthosomatic (with C probably representing a fusion of the pregenital [body segment VII] and genital [VIII] segments).  Others believe that C and D are the dorsal regions of the last two prosomal segments that bear leggs III and IV (i.e., body segments V & VI).

Sejina: older name for the suborder Sejida

sejine: representative of the mesostigmatan suborder Sejida.  

sejugal suture: (or plane) a division cutting the acariform mite idiosoma between legs II-III.

sensillum: (pl. sensilla) (also sensillae; 'sensillus' is incorrect) a sensory structure;  sensilla is often used for the bothridial seta in Acariformes.

serrate: with closely set teeth that resemble the cutting edge of a saw.

seta: (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.

setal: of or pertaining to a seta.

setule: a small, seta-like cuticular process, typically on the pretarsal empodia or claws.

sigilla: muscle insertions ('scars'), usually visible as depressed and / or striate regions ('scars') on plates, oval or irregular in shape and often in clusters.

sigillotaxy: the use of cuticular muscle insertions as taxonomic characters (designation = sg).

sigla: designations for setae.

Sigma: (Σ) designation for solenidion the genu of acariform mites, (Φ (phi) on the tibia; Ω (omega) on the tarsus).

silk: fine threads spun by acariform mites to form a molting chamber (cocoon), protect or attach eggs, or a loosely defined to finely woven web.

simple: unadorned; simple setae are needle-like and without hairs or pectins.

sinuate: with a winding, snake-like, or wave-like form, as in the peritremes of some Uropodidae (Mesostigmata) or the setae of various mites.

slit sense organ: a lyrifissure; a stretch receptor.

snout mite: usually referring to a member of the Bdelloidea (Prostigmata: Bdellidae, Cunaxidae), but more loosely used for any mites with a well developed, projecting gnathosoma.

soil mite: any mite found in the soil-litter or decomposition subsystem.

soil-encrusted: mites with an adherent layer of soil particles; probably a tactile camouflage.  

solenidion: (pl. solenidia) a hollow, optically inactive chemosensory seta on the limbs of acariform mites appearing to have transverse rows of minute pores (actually pore canals) under light microscopy, (the transverse pattern is often not apparent in SEM); often bulbous or otherwise modified; sometimes associated with a companion seta.  Solenidia are designated with Greek letters by leg segment: Ω (omega) on the tarsus, Φ (phi) on the tibia, and Σ (sigma) on the genu.

solenostome: the external opening of a gland or gland-like internal structure (e.g., the sperm induction pore in sperm access systems).

sp. nr.: species near, used for uncertain species designations (e.g., Cosmolaelaps sp. nr. vacua (Michael)), implying that the specimen referred to may represent a new species (see aff., nr., and cf.); a less nebulous use of this formation is 'n. sp. nr.', i.e. new species near, and indicates that the taxonomist is convinced that the specimen represents an undescribed species related to the attributed species.

spathulate: (Latin spatula = spoon) flat at the base and enlarged at the apex; spathulate and spatulate are often used interchangeably.  

spatulate: (Latin spatula = spoon) spatula-shaped; variously interpreted, but usually referring to setae that are flattened and somewhat expanded distally.

sperm access system: a term used for a complex secondary insemination system in in female mites; implies more than simple sperm storage is occurring.    In the dermanyssine Mesostigmata, two basic types of sperm access systems are known - the laelapid type and the phytoseiid type.

spermadactyl: see spermatodactyl

spermatheca: a structure in the female for storing sperm, typically sac-like.

spermathecal tube: any duct or other tubular structure connecting to or a part of a sperm storage structure.  In Eriophyoidea the spermathecal tube is poorly expressed in Eriophyidae and Diptilomiopidae; in the Phytoptidae the spermathecal tube is more distinct and much longer than the spermatheca in the subfamily Napellinae

spermathecalduct: see spermathecal tube

spermatodactyl: (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.  

spermatophore: any structure that carries a packet of sperm, including complex stalks deposited on substrate by male acariform mites and flask-like structures carried on the chelicerae of male mesostigmatans.

spermatotreme: a slit-like opening on the movable digit of male Parasitidae that grasps the neck of the spermatophore during sperm transfer; considered to be a foramen left by the distal fusion of a spermatodactyl to the movable digit.

spider mite: a member of the family Tetranychidae (Prostigmata).

spinae adnatae: a pair of tooth-like projections on the anterior margin of the notogaster of damaeid oribatids.

spine-like: a seta or other structure that resembles a thorn or spine; spiniform.

spiniform: with the form of a tapering, spine-like process, tubercle or seta.  

spinneret: a structure that produces silken fibers.  In spider mites, the spinneret is in the form of a short, blunt seta-like structure on the palp tarsus.

spinule: a small, spine-like cuticular process.

sporotheca: (pl. sporothecae) sack-like structures used to carry fungal spores; typically paired, eversible ventral recesses in the Heterostigmatina.

spur: a projection, usually tooth- or spine-like, from the body or limbs.

stage: a distinct developmental form, e.g., the egg, larval, nymphal and adult stages.  Since mite instars are usually morphologically distinct, they are also stages (and see stase).  Some authors, however, insist that instar should be apolysis to apolysis and stage ecdysis to ecdysis.  Since apolysis can be a discontinuous process and, in any case, is difficult to determine, in practice the difference between a stage and an instar is abstract and of importance only if you have a contentious referee.

stalked: raised up or otherwise produced on a stalk.

stase: one of the successive, morphologically distinguishable forms exhibited by a mite during development.  A stase is equivalent to an instar in mites; but theoretically, if no setal or other morphological changes occur across a molt, then several instars may occur in one stase.  Mostly used by Grandjean and his followers as a theoretical concept.

stegasime: having the chelicerae protected dorsally by a rostral tectum (see astegasime), as in most oribatid mites.

stellate: star-like.  

stenarthric: a subcapitulum with a triangular mentum and oblique labiogenal sutures; probable primitive condition in Acariformes.

stenoxenic: (-ous) using a narrow range (e.g., of habitats or hosts); more or less host specific, habitat specific, etc.

sternal pores: (designations = stp or iv) in Mesostigmata, the lyrifissures in the intercoxal region; stp1-2 often occur on the sternal shield and stp3 is associated with the metasternal setae on a combined sternal-metasternal shield, on a separate sternal platelet, or in soft cuticle.

sternal setae: in Mesostigmata, the five pairs of setae in the intercoxal region designated st1-5; st1-3 are present in the larva and usually are borne on a sternal shield in the adult female; st4, the metasternal setae, are added in the deutonymph, often are borne on metasternal platelets, and sometimes on the sternal shield; st5, the genital setae, are added in the protonymph and usually borne on or are inserted laterad the epigynal shield in the adult female.

sternal shield: a shield in the anterior intercoxal region of parasitiform mites that bears one or more pairs of sternal setae.

sternogenitalshield: (also sternitogenital, sternitigenital) in male Mesostigmata, a shield covering the intercoxal region and bearing the genital opening.  

sternovaginal sclerites: a pair of posterior internal processes in the pregenital region of female trigynaspid mesostigmatans in the superfamily Aenictequoidea.

stigma: the opening to the tracheal system.

straw-itch mite: a member of the genus Pyemotes (Prostigmata: Pyemotidae) whose bites cause large itchy wheals on people.

striae: the raised, narrowly aligned cuticular ridges, often like a fingerprint or plicate pattern; striations.

striations: a pattern of raised, narrowly aligned cuticular ridges, often like a fingerprint or plicate pattern.

stylet: (Latin stylus = pricker) a narrow, pointed structure, typically referring to a mouthpart in the Acari.

stylet sheath: (= cheliceral sheath, rostral gutter) the median anterior process of the capitulum bearing a gutter, U-shaped in cross section, that enclosed the 7-9 stylets in the Eriophyoidea.

stylet-like: referring to chelicerae or movable digits that are slender, elongate, and usually acuminate.  Stylet-like chelicerae may be composed of the entire chelicera (as in some parasitic Dermanyssoidea or the endeostigmatan genus Bimichaelia) or only the movable digits (as in many Prostigmata).  If the cheliceral stylets are especially elongate, they may be called whip-like stylets (e.g., in spider mites and their relatives).

stylettiform: stylet-like.

styliform: stylet-like.  

stylophore: chelicerae formed of fused cheliceral bases bearing stylet-like movable digits as in Raphignathae (Prostigmata), e.g., the plant parasitic spider mites and their relatives (Tetranychoidea).  In predatory and parasitic Cheyletoidea and parasitic Myobiidae, the stylophore and subcapitulum are fused into a gnathosomal capsule.

stylostome: a ramifying structure produced in the skin of a host by the feeding of a chigger or larval water mite.

sub:  - as prefix used to indicate (1) under (see subcapitulum) or (2) not quite, e.g., subrectangular = not quite rectangular; subtriangular = not cleanly triangular.

subcapitular plate: an apodeme that supports the chelicerae ventrally and to which the muscles of the labrum are attached.

subcapitulum: (also infracapitulum) the venter of the capitulum; the ventral faces of the fused palpcoxae; apparently formed independently in the two superorders of mites.

subcheliceral plate: the internal sclerotized plate on which the chelicerae rest.

subdorsal seta: in the Eriophyoidea, opisthosomal seta c1.

sublateral setae: in Phytoseiidae, setae r3 and R1 (rarely r5).

sublaterals: Sublateral  opisthosomal setae of spider mites in the Pritchard & Baker (1955.  A revision of the spider mite family Tetranychidae.  Mem. Pac. Coast Entomol. Soc. 2: 1-472.).  1st sublaterals = c3; 2nd sublaterals = d3; 3rd sublaterals = e3 in the Grandjean system.

subtriangular: more or less triangular.  

subulate: awl-shaped; used to describe short spinose structures such as some setae..

subunguinal seta: (s) an unpaired seta between the unguinal and anterolateral pairs on the tarsi of acariform mites (see whorl).

sucker: an attachment organ (most appearing to be of setal origin) as found in the ventral suckers of Heterozerconoidea, the tarsal and ventral suckers in male Astigmatina, the posterior sucker in male Tarsonemina, and the sucker plate of Astigmatina deutonymphs.

sucker plate: an array of modified setae in the anal region of the heteromorphic deutonymphs (hypopi) of Astigmatina.

suctorial: in reference to mouthparts that appear to be used to suck-up fluids, although in most cases this has not been demonstrated and may not be true.  Typically the chelicerae are stylet-like and the subcapitulum is modified anteriorly into a tube that supports the stylets, e.g., in the endeostigmatan genus Bimichaelia and the oribatid superfamily Suctobelboidea.

supernumerary: more than there are supposed to be; stages or structures thought to have been added to the basic number, e.g., some argasid ticks have more than three nymphal instars.

supracoxal seta: an often inflated or otherwise elaborated dorsal coxal seta in astigmatans associated with the supracoxal gland opening; minute peg-like seta (ep) on the dorsal palp coxa or coxa of legs I in acariform mites.

suranal seta: a minute unpaired seta inserted dorsal to the terminal anus in some diarthrophallid Mesostigmata.

suture: an inflexible juncture between two body parts; line of fusion between two formerly separate body parts or regions.  This term is often misused for flexible articulations.

tapering: drawn out or with margins converging.

tapetum: the reflective area under the lens of some mites (e.g., Opilioacarida).

tarsal apotele: (also pretarsus) the most distal segments of legs and palps bearing the claws and empodium

tarsal appendages: the tarsal apotele.

tarsonemid: a mite belonging to the family Tarsonemidae including many economically important species (e.g., species of Acarapis, Tarsonemus, Polyphagotarsonemus, Phytonemus).

Tarsonemoidea: (also Tarsonemina) a superfamily within Prostigmata > infraorder Eleutherengona > hyporder Heterostigmata consisting of two families: Tarsonemidae and Podapolipidae.

tarsus: (pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).

tectals: (tc) a pair of dorsal tarsal setae between the iterals and the fastigals on the tarsi of acariform mites (see whorl).

tectopedium: (pl. tectopedia) shelf of cuticle protecting the base of the leg of an oribatid mite (see pedotectum)

tectum: (pl. tecta) any shelf-like projection of the cuticle.  In Mesostigmata the leading dorsal edge of the basis capitulum is referred to as the tectum, gnathotectum, or epistome.

tectum capituli: the tectum or epistome of Mesostigmata

tegmen: (pl. tegmina) a term sometimes used for the gnathosomal capsule of some Prostigmata.  Also the leathery forewings of orthopteroid insects.

tegula: lobe-like to acuminate tectum projecting posteriorly between coxae IV in Tarsonemidae.

telofemur: (pl. telofemora) a distal division of the femur.

telosome: a fancied posterior region of the opisthosoma of Eriophyoidea composed of the anal lobe and the preceding 3-8 annuli; opposed to the thanosome.

telotarsus: (= acrotarsus, apicotarsus) a distal division of the tarsus.  

tenent hair: a seta or seta-like process with a flattened tip that resembles the head of a nail; usually used for hair-like processes on the claws or empodium of acariform mites, but at least some oribatid mites have true tenent hairs, i.e. modified setae.

terete: having the form of a smoothly tapering cylinder.  

tergite: the plate-like dorsal annuli of some Eriophyoidea.

tetartosternum: in Mesostigmata, an unpaired presternal shields bearing setae st1 and /or pores stp1.

Tetrapodili: an obsolete name for the Eriophyoidea; the name reflects the presence of four legs.

Tetrastigmata: an obsolete name for the Holothyrida based on the misinterpretation of the openings to Thon's gland as being a second pair of stigmata.

thanatosis: playing dead; usually involves pulling in the legs and palps against the body and avoiding movement for extended periods.

thanosome: a fancied region of the opisthosoma of Eriophyoidea composed of all except the last 3-8 annuli and anal lobe (opposed to the telosome).

thelytokous: exhibiting all female parthenogenesis (thelytoky).

thelytoky: all-female pathenogenesis.  

Thon's organ:  a gland that opens on the lateral dorsal shield posterior to the peritreme in the Holothyrida; once confused with a second stigmatal opening.

thumb-claw: a hypertrophied, usually claw-like seta on the dorso-distal margin of the palptibia that forms a pincer with the palptarsus of some Prostigmata; the palp thumb-claw complex.

tibia: (pl. tibiae) the leg segment between the genu and the tarsus.

tick: any member of the parasitiform suborder Ixodida.

tocospermy: a sperm transfer system where the spermatophore is deposited directly into the female genital opening.

tong-like: resembling a pair of ice tongs; helicerae that resemble opposed hooks, usually edentate or at most with small teeth.  

tortoise mite: member of the Uropodoidea (Mesostigmata) with recesses into which the head and legs (pedofossae) can be withdrawn (see also turtle mite).

tracheae:  the long, filamentous tubes that ramify through the body of some mites for the exchange of gases.

trachealmite: Acarapis woodi (Rennie) a tarsonemid mite that lives parasitically in the tracheae of honeybees and is associated with the development of Isle of Wight Disease.  Other species of Acarapis live externally on bees.

Tragardh's organ: a flat, finger-like paraxial projection on the chelicerae of some oribatid mites; usually difficult to see unless the chelicerae are dissected out.  

translamella: a transverse ridge joining the lamellae on the prodorsum of some oribatid mites.

tricarinate: having three longitudinal ridges as in the dorsal shield setae of most Lasioseius.

trichobothrium: (pl. trichobothria) (= bothridial sensillum) an often elaborately modified seta set in a cup-like base; forms include filiform, ciliate, pectinate or variously thickened or clubbed (bat-like to globose or capitate).

trichocyst: a trichobrium-like subbasal seta on tarsus I of deutonymphal veigaiid Mesostigmata.

trichoidy: having a body divided into three as in some lower Oribatida.

trichome: a seta.

tricuspid: having three points or cusps, e.g., the gnathotectum of some Mesostigmata.

tridactylous: having three claws.  

trifurcate: split into three distally.

trigynaspine: representative of the mesostigmatan suborder Trigynaspida, characterized by having three genital shields in the adult female (range 1-4).

tritonymph: the third, and final, nymphal stage or instar present in Opilioacarida, Holothyrida, Argasidae, and many Acariformes.

tritosternal base: the usually columnar basal part of the tritosternum; sometimes expanded and rectangular or otherwise modified.

tritosternum: 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.  

trochanter: the leg segment between the coxa and the femur.

trombidiosis: a dermatitis caused by infestation by larval trombiculoid mites (chiggers); also called scrub itch.

tropical fowlmite: Ornithonyssus bursa (Berlese): Mesostigmata, Dermanyssoidea, Macronyssidae.

tropical ratmite: Ornithonyssus bacoti (HIrst): Mesostigmata, Dermanyssoidea, Macronyssidae.

tuberculate: ornamented with raised processes; covered with tubercles.

tubulus annulatus: the long tube running from the base of the sacculus vestibulus to the ramus sacculus in mesostigmatans with laelapid-type sperm access systems.

turtle mite: a member of the heterostigmatan family Scutacaridae (Prostigmata); see also tortoise mite.

tutorium: (pl. tutoria) a ridge on the lateral prodorsum of oribatid mites, ventral and more or less parallel to the lamella and protecting legs I when retracted.

tydeid mite: a member of the family Tydeidae (Prostigmata, Eupodina).  Tydeid mites are often found on vegetation, but none are important plant parasites.  Most seem to feed on leaf fungi, other mites, and honeydew.

uncate: pincer-like; in water mites (Hydrachnida), uncate palps have a ventral palptibial process opposed to a dorsal movable palptarsus (opposed to chelate).

uncinate: hook-like

unguinals: (u) the distalmost ventral pair of setae at the base of the ambulacrum on the tarsi of acariform mites (see whorl).

unideficient: lacking one seta from the assumed holotrichous condition.

uropore: anus.

urpore: see urstigma.

urstigma: (pl. urstigmata) the presumed homologue of the genital papillae found between legs I-II in the prelarvae and larvae of many acariform mites; osmoregulatory organs (= Claparède's organ, also urpores, bruststiele). Tydeid mites may retain the urstigmata beyond the larval stage.

vaginal sclerites: in Mesostigmata, a pair of internal sclerites in the genital region.

vagrant: a mite that lives on leaves or other plant parts without forming galls or webbing; the term is commonly used to refer to certain Eriophyoidea; see rust mite.

Van der Hammen's organ: a respiratory organ in some intertidal Oribatida (e.g., Fortuynia spp.) composed of cuticular tubercles and the overlying cerotegument.

vas deferens: the tubules that conduct the sperm from the testes.

velvet mite: the nymphal or adult stage of a terrestrial member of the Parasitengona (Prostigmata) that feed on small arthropods and their eggs.  Larval stages of one superfamily (Trombiculoidea) are the annoying chiggers.

venter: the lower or under side; opposed to dorsum.

ventral: relating to the lower or under side; opposed to dorsal.

ventral plate: a sclerotized plate covering the ventral region of the opisthosoma in brachypyline oribatid mites and separated from the notogaster by the circumgastric scissure; also any plate in the ventral region.

ventral region: in Mesostigmata, the area between the genital and anal regions.

ventral 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.

ventral shield: in Mesostigmata, any shield or shields in the ventral region; often fused with the anal shield to form a ventrianal shield. [Back to Top]

ventralseta I: (or 1st ventral seta) in the Eriophyoidea, opisthosomal seta d.

ventralseta II: (or 2nd ventral seta) in the Eriophyoidea, opisthosomal seta e.

ventralseta III: (or 3rd ventral seta) in the Eriophyoidea, opisthosomal seta f.

ventrianal 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.

verruca: (pl verrucae) a wart-like process.

verrucate: ornamented with irregular raised tubercles; covered with wart-like structures.

vertex: an anterior extension of the idiosoma that covers the capitulum in many uropodid mites.

Vertical-scapular system: a system of designations for the prodorsal setae in Acariformes, especially in the Endeostigmata and Prostigmata.  Prodorsal setae exp, in or both are often lost.  In the Prostigmata, the prodorsal setae are represented at their maximum by the interior and exterior vertical (vi, also v1; ve, also v2, z2) and internal and external scapular setae (sci, also si, s1; sce, also se, s2) (a possible exception exists in Pilorhagidia which has 5 pairs).  In Astigmata, the traditional designations follow those used in the Prostigmata; however, the purported internal scapular setae (sci or si) actually are in.  In Oribatida, the Rostral-lamellar system is more commonly used (ro, le, bo, exa, in, exp, respectively).

verticalsetae: in the Mesostigmata, the anteriormost pair of median setae in the j-series, setae j1; usually projecting over the gnathosoma, often modified, and inserted across a lyrifissure from the paravertical setae z1.  In the Acariformes, setae sci and sce (see Vertical-scapular system).

verticil: a whorl of setae around a region of a leg segment used in determining setal designations.

vesicle: in phytoseioid Mesostigmata (Phytoseiidae, Blattisociidae, Otopheidomenidae), a sack-like structure supported by the calyz where endospermatophores can often be seen.

viviparity: live birth; emergence of prelarval (prelarviparity), larval (larviparity), nymphal or adult (see physogastry) mites from their mothers body after the internal hatching of the eggs (technically, most mites are actually ovoviviparous).

viviparous: exhibiting viviparity (live birth, rather than egg laying).

wandernymph: German term for a phoretic nymph, especially in the Uropodina and Sejida.

water mite: a member of the Hydracarina (also Hydrachnidia, Hydrachnellae) (Prostigmata, Parasitengona).  Water mites are often large and brightly colored.  Their larval stages are usually parasitic on aquatic insects.

western predatory mite: the phytoseiid mite Galendromus (also Metaseiulus, Typhlodromus) occidentalis (Nesbitt), a biocontrol agent of spider mites.

whip-like: long, slender and sinuous as in the posterior setae of some phytoseiid mites (Mesostigmata) or the stylets of spider mites and their relatives (Prostigmata: Tetranychoidea).

whorl: one of the whorls or verticils of birefringent setae on the leg segments of acariform mites.

wing-like: projecting from the body or other structures like the wings of insects.

witches' broom: clusters of abnormal, brush-like growths of stunted twigs or branches on trees, caused by various organisms, including mites.

With's organ: a membranous structure on the anterior margin of the subcapitulum in Opilioacarida.

worm-like: elongate, with reduced legs as in some Nematalycidae (Endeostigmata).

xylophage: feeding on wood. Some oribatid mites are xylophagous

Y-tube olfactometer: an experimental devise, typically a tube with three arms in a Y-shape, often used for testing of the response of phytoseiid mites to chemical scents

zerconine: representative of the Zerconoidea (Mesostigmata: Monogynaspida: Epicriiae)

zeta: (?) designation for eupathidia on the legs of acariform mites

zoorhria: the use of animals for migration (see phoresy)