Keys to NorthAmerican Genera

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FAMILY ACARIDAELatreille, 1802

synonymy:

KEY TO NORTH AMERICAN GENERA OF THEFAMILY ACARIDAE

ADULTS

1. External vertical setae located on the same transverseline as internal vertical setae or slightly posterior; hysterosoma with12 pairs of setae, some of which are often elongate and finely barbed..................................................................................................................2.

External vertical setae located approximately midway betweeninternal verticals and scapular setae or external verticals absent; hysterosomaoften with fewer than 12 pairs of setae; setae rarely elongate and barbed.............................................................................................13.

2. Genu I with solenidion sigma-1 at least three timeslonger than sigma-2; ventral apex of tarsus with proral and unguinal setaethin, not short, stout spines; male with leg I enlarged and bearing a ventralapophysis on femur; in stored products and vertebrate nests ................Acarus

Genu I with solenidion sigma-1 no more than three timeslonger than sigma-2; ventral apex of tarsi with proral and unguinal setaeusually in the form of short, stout spines, or one pair absent; male withoutmodifications of leg I..........................................................................3.

3. Length of internal scapular setae approximately equalto or shorter than external scapular setae .......................4.

Internal scapular setae distinctly longer than externals....................................8.

4. All dorsal idiosomal setae smooth, unbarbed..............................................5.

At least some dorsal idiosomal setae with barbs or withbifurcate ends.............6.

5. All dorsal idiosomal setae relatively long, overlappingbase of next posterior seta; supracoxal seta strongly barbed; coxal seta3a present; in nests of small sphecid wasps (Psenulus, Stigmus)..............................................Lackerbaueria

Dorsal idiosomal setae (except sce, h3) short, not overlappingbase of next posterior seta; supracoxal seta simple, unbarbed; coxal seta3a absent; in nests of Anthophora and occasionally Diadasiabees (Apidae)..................................................................Medeus

6. Legs strongly tanned; dorsal idiosomal setae very weaklybarbed or smooth; 1 species, A. ovatus, in stored products ........................................Aleuroglyphus

Legs not tanned; dorsal setae heavily barbed...................................................7.

 

7. Dorsal setae tapering to fine points; in stored products................Madaglyphus

Dorsal setae rounded at tips; in nests of ants and honeybees...............Forcellinia

8. Internal scapular setae more than 5 times longer thanexternal scapulars; in nests of Chalicodoma bees (Megachilidae)....................................Cerophagopsis

Internal scapular setae at most twice the length of externalscapulars.................9.

9. External vertical setae (ve) less than 1/3 the lengthof internal verticals(vi); male aedeagus long and straight; in decayingmaterials, occasionally stored products..................................................................................Mycetoglyphus

External vertical setae more than 1/3 the length of internalverticals; male aedeagus usually short and often curved.......................................................10.

10. All hysterosomal setae except c1 elongate, longer thanthe distance to the next posterior seta.............................................................................................11.

Hysterosomal setae c1 and at least one other pair of setae(often d1 or d2) shorter than the distance to the next posterior seta....................................................12.

11. Seta c1 unbarbed, positioned often very close to setad1; tarsi tanned, with a dorsal ridge; some para-anal setae of female shorterthan distance between them; in nests of Bombus bees (Apidae).........................................................Kuzinia

Seta c1 barbed, positioned more anteriorly; tarsi withoutdorsal ridge; all para-anal setae of female longer than the distance betweenthem; l species, T. casei, in a variety of habitats often involvingsugar-based substrates.....Tyrolichus

12. Tarsi I-II short, approximately twice as long as basalwidth; proral setae very reduced; Grandjean's organ flattened and fimbriate;in stored products and hymenopteran nests.........................................................................Tyroborus

Tarsi I-II more than twice as long as basal width; proralsetae thinner than unguinal setae but similar in length; Grandjean's organfinger-like; in a variety of field and storage habitats................................................................Tyrophagus

13. Legs III-IV of both sexes strongly modified, with tibiae-tarsifused; empodial claws III-IV greatly enlarged, hook-like, opposable withstructures at base of tibio-tarsus; associated with hermit crabs (Coenobitidae)................................14.

Legs III-IV of female with tibiae-tarsi freely articulated;male as female or with legs III enlarged; empodial claws not opposable withstructures on base of tibia ................................................................................................................15.

14. Empodial claws III-IV opposable to a large, strong,cuticular tubercle on the basal portion of tibio-tarsus; tubercle bearing3 modified setae at its apex; on gills of Coenobita......................................................................................Ewingia

Empodial claws III-IV opposable to a large hypertrophiedseta arising from the base of tibio-tarsus; on body setae behind gills ofCoenobita........................Askinasia

15. External vertical setae present on lateral sides ofprodorsal sclerite approximately halfway between internal vertical setaeand scapular setae, length of ve setae greater than 10um; tarsi I-II eachwith seta ft' present, filiform, not associated with solenidion omega-1..............................................................16.

External vertical setae absent, or if present (some Rhizoglyphus),then less than 10um long; tarsi I-II with seta ft' spine-like and closelyassociated with omega-1, or filiform on tarsus I but absent on tarsus II(Neotropacarus) or absent on both tarsi..........................................................................................................21.

16. Tibiae I-II with 1 ventral seta; tibiae IV withoutventral seta; prodorsal sclerite weakly developed; in nests of Xylocopaspp. (Anthophoridae).......Horstia

Tibiae I-II with 2 ventral setae; tibiae IV with 1 ventralseta; prodorsal sclerite well-developed...........................................................................................17.

17. Tarsi I-II with 2-3 foliate setae, seta pv" alwaysfoliate and positioned posteroapically; tibial setae often spine-like; supracoxalsetae simple, sometimes greatly reduced or absent............................................................................18.

Tarsi I-II with one foliate seta (tc') or none; seta pv"filiform, positioned medially or apically; supracoxal setae variously formed.................................19.

18. Seta ft' of tarsi I-II filiform; female with copulatoryopening separated from posterior end of anus by a distance greater thanhalf the length of the anus; in decaying organic matter or often associatedwith scarabaeoid beetles............Sancassania (=Caloglyphus)

Seta ft' of tarsi I-II spine-like; female with copulatoryopening directly posterior to anus; in soil, decaying wood, vertebrate nests.....................................................Viedebanttia

19. Tarsi I-II with seta pv" posteroapical in position;supracoxal setae inflated basally and heavily barbed; tibial setae spine-like;in field and storage habitats, often associated with ants or termites...........................................Cosmoglyphus

Tarsi I-II with seta pv" posteromedial in position;supracoxal setae variously formed, inflated basally or thin, nude or barbed;tibial setae filiform..............20.

20. Female with internal spermatheca large, bearing sclerotizedramifications, openings to oviducts widely separated; tarsi I-II with setatc' thinly foliate or filiform; supracoxal setae inflated basally or thin;in vertebrate nests, tree holes and storage habitats.......................................................................Acotyledon

Female with spermatheca simple, openings to oviducts approximate;supracoxal setae thin and nude; 1 species, N. rhizoglyphoides, instored products, insect and vertebrate nests.......................................................................Neoacotyledon

21. Dorsal cuticle ornamented with raised protuberances;hysterosomal setae long and heavily barbed; in decaying wood................................................Fagacarus

Dorsal cuticle smooth; hysterosomal setae simple..........................................22.

 

22. Tarsi I-II with seta ft' absent, or if present on tarsusI, then filiform (Neotropacarus).........................................................................................23.

Tarsi I-II with seta ft' in the form of a spine directlyadjacent to solenidion omega-1....................................................................................................24.

23. Tarsi I-II with seta ft' absent; tarsi short, no morethan twice as long as wide; body elongate; male with para-anal suckers well-developed;often associated with dead insects, subcortical habitats or stored products......................................................Thyreophagus (=Moniziella=Fumouzea =Michaelopus)

Tarsus I with ft' present, filiform; ft' absent from tarsusII; tibiae I-II with 1 ventral seta; legs long, tarsi more than four timeslonger than wide; body rounded; male with para-anal suckers vestigial; phytophagousor fungivorous on tree foliage...............................................................................Neotropacarus

24. Legs long, at least 50% of the body length; empodialclaws long and blade-like; male with posterior opisthosomal sclerite wellremoved from posterior edge of body; aquatic, in water-filled tree-holes.................Naiadacarus

Legs no more than 40% of body length, usually shorter;empodial claws strong, usually not long and blade-like; male with opisthosomalsclerite, if present, at posterior margin of body; usually terrestrial................................................25.

25. Both sexes with body elongate, female body at leastthree times longer than wide; both sexes with posterior hysterosoma sclerotizedor tanned; supracoxal seta (scx) elongate and filiform; tibiae I-II withonly one ventral seta (vT" absent); all males homeomorphic with legsIII normally developed; in spore tubes of woody bracket fungi (Polyporaceae)

..................................................Boletoglyphus(=Fantovia, =Ellipsopus, =Lindquistia)

Body rounded or elongate but not more that 2.5 times longerthan wide; male often with posterior hysterosomal sclerite but female alwayswithout; supracoxal seta (scx) very short or absent; tibiae I-II with oneor two ventral setae...........26.

26. Hysterosoma with maximum complement of dorsal setae(12 pairs); internal scapular setae present although usually short (absentin 1 species); in soil, decaying vegetable material, fungi or in intactbulbs and corms.......Rhizoglyphus

Hysterosoma with at most 7 pairs of dorsal setae; setaec1 and f2 always absent; internal scapular setae usually absent...........................................................27.

27. Tarsi 2.5-4 times longer than wide; most dorsal hysterosomalsetae longer than the distance to the next posterior seta; male with a terminalposterior expansion bearing 4 modified, fan-like setae; associated withwood-boring insects, occasionally in stored products...........................................Histiogaster

Tarsi less than twice as long as wide; hysterosomal setaeshort, not usually longer than the distance to the next posterior seta;male without posterior projection..28.

28. Dorsal surface entirely sclerotized, without distinctprodorsal sclerite; anterior hysterosomal cupules ia greatly enlarged intodorsolateral lyriform organs; legs I-II short, stout; tarsal setae ft' andtc" I-II greatly enlarged spines; tarsi I-II with only 2 filiform/foliatesetae (ft", pv" - setae a' short, spinelike); only homeomorphicmales known; in caves and decaying organic matter ........................................................................Stereoglyphus(=Troglocoptes)

Dorsal surface usually unsclerotized except for prodorsalsclerite (rarely totally sclerotized); anterior hysterosomal cupules iasmall, rounded; legs I-II variable in form; tarsi I-II with 3 filiform/foliatesetae (ft", pv", a'); heteromorphic males common; in soil, litter,decaying wood, fungi, tree holes, or in semiaquatic to aquatic habitats...............................................................................Schwiebea

Note: Adults of the genera Trichopsyllopus, Paraceroglyphus, Schulzea,Diadasiopus and Sennertionyx are unknown.

DEUTONYMPHS

("inert" deutonymphs of Acarus and Stereoglyphusnot included)

 

 

1. Posterior apodeme of coxal field II fused with anteriorapodeme of coxal field III or running parallel for much of its length; empodialclaws often enlarged and hook-like; genital papillae pointed, often elongateand tapering to a fine point; coxal setae I, III filiform or absent; associatesof bees................................2.

Posterior apodeme of coxal field II free posteriorly althoughit may end near the anterior apodeme of coxal field III (if fused with apodemeIII, then coxal setae conoidal); empodial claws not enlarged and hook-like;genital papillae short, broadly rounded apically; coxal setae often conoidal;most genera not associated with bees (exceptions occur) ........................................................6.

2. Tarsus IV with 2 or 3 long setae, each longer than thelength of leg IV.........3.

Tarsus IV with at most one seta longer than the lengthof leg IV......................4.

3. Empodial claws I-IV large and hook-like; claws I-IIIdistinctly larger than claws IV; tibiae I-II with 2 ventral setae; associatedwith Anthidium bees (Megachilidae).......................................................................Sennertionyx

Empodial claws I-IV short, strong, not hooked; all clawssimilar in size; tibiae I-II with 1 ventral seta; associated with Xylocopabees (Apidae).............Horstia

4. Genu I with 2 solenidia; associated with Halictidae.............................Schulzea

Genu I with 1 solenidion; associated with Megachilidaeand Apidae..................5.

5. Coxal setae 3b and 4a present, filiform, setae 3a absent;posterior apodeme of coxal field II divided; posterior dorsum with welldeveloped longitudinal apodemes; associated with Anthophora and Diadasia(Apidae).................Medeus

Coxal setae 3b and 4a absent, setae 3a present, filiform;posterior apodeme of coxal field II continuous; posterior dorsum withoutlongitudinal apodemes; associated with Chalicodoma (Megachilidae)................................Cerophagopsis

6. Propodosoma with a pair of pigmented eye-spots........................................7.

Propodosoma without eye-spots....................................................................9.

7. Eyes widely separated in middle of propodosoma; distinctlenses present; usually on wood-associated insects...............................................Thyreophagus

Eyes contiguous or closely separated on anterior edge ofpropodosoma; lenses often indistinct or absent................................................................................................8.

8. Coxal apodemes III-IV ending freely, not fused to eachother medially.........Histiogaster

Coxal apodemes III-IV fused to each other medially......................................Calvoliella

9. Attachment organ vestigial, with 1 pair of suckers;gnathosomal solenidia long ....................................................................................................Acotyledon

Attachment organ well developed with 2 pairs of suckersand 2 pairs of conoidal setae, or if vestigial ("inert" deutonymphs)then gnathosomal solenidia vestigial .................................................................................................................10.

10. External conoidal setae (ps2) of attachment organ completelyanterior to median sucker (ad1+2); sternum elongate, reaching transversemedian apodeme .................................................................................................................11.

External conoidal setae of attachment organ lateral orposterior to median sucker; sternum shorter, usually not reaching transversefurrow....................13.

11. Dorsal body setae simple; tarsus III and IV with nosetae longer than legs; associated with ants .................................Forcellinia, Mycetoglyphus and Tyrophagus
(Note: These genera are not separable morphologically.)

Dorsal body setae elongate and pectinate or stiffened andspine-like; tarsus III with 1 and tarsus IV with 2 setae longer than theirrespective legs; associated with bees and wasps ............................................................................................12

 12. Coxal setae 1a, and 3b conoidal; dorsal bodysetae elongate and pectinate; associated with sphecid wasps ......................................................Lackerbaueria

Coxal setae 1a & 3b filiform; dorsal body setae spine-like;associated with Diadasia bees (Apidae) ...................................................................Diadasiopus

 13. Attachment organ with all 4 conoidal setae ina transverse row completely posterior to median suckers ........................................................................14.

Attachment organ with lateral conoidal setae more anteriorthan posterior conoidal setae, not completely posterior to median suckers............................15.

 14. Dorsal median hysterosomal setae elongate andlanceolate; attachment organ wider than long, with large, circular mediansuckers; coxal apodemes III-IV fused medially to each other and median apodeme;in polypore fungi, phoretic on Bolitophagini (Tenebrionidae) .....................................................Boletoglyphus

Dorsal setae simple and filiform; attachment organ longerthan wide, with small, oval median suckers; coxal apodemes III-IV fusedto each other on each side but not fused medially to median apodeme; instored products, vertebrate nests; often phoretic in fur of mammals ........................................................Neoacotyledon

 15. Genua III-IV distinctly longer than tibiae III-IV;tarsi III-IV often projecting at an angle from tibiae III-IV .....................................................Cosmoglyphus

Genua III-IV subequal to or shorter than tibiae III-IV;tarsi III-IV not projecting at an angle from tibiae III-IV ......................................................................16.

 16. Genu III with a short dorsal solenidion (sigma).......................................17.

Genu III without solenidion ........................................................................18.

 17. Coxal fields closed but widely separated medially;tarsi about twice as long as wide; gnathosoma short, about as wide as long;associated with Bombus bees (Apidae) ..............................................Kuzinia

Coxal fields III closed, nearly contiguous medially; tarsiat least three times longer than wide; gnathosoma at least twice as longas wide; associated with Syrphidae flies .............................................................................Naiadacarus

 18. Solenidion omega-2 of tarsus I absent; posteriorventral setae of tibiae I-II and sometimes genua I-II usually filiform anddistinctly barbed; internal vertical setae usually long and barbed; phoreticon fleas or carrion or grain insects ......19.

Posterior setae of tibiae I-II and genua I-II stout andspine-like, smooth or barbed, or thin and unbarbed, never both filiformand barbed; solenidion omega-2 of tarsus I present; internal vertical setaeunbarbed ..........................21.

 19. Posterior apodemes of coxal fields II well-developed,continuous; body dorsum usually punctate, rarely smooth; scapular setaeusually elongate, rarely short; or body and leg setae vestigial, gnathosomalsolenidia and attachment organ vestigial (inert forms); in stored products,vertebrate nests, often phoretic on fleas or grain beetles .......................................................................Acarus

Posterior apodemes of coxal fields II very weakly developed;body dorsum smooth; scapular setae always short; no inert forms known ............................20.

 20. Coxal apodemes III-IV ending freely; coxal fieldsIII widely open medially; no posterior median longitudinal apodeme anteriorto genital region; 1 species from fleas associated with mountain beavers(Aplodontia), NW coast .............................Trichopsyllopus

Coxal apodemes III-IV fused to each other on both sides,closing coxal fields III; posterior median apodeme present anterior to genitalopening; phoretic on fleas ..................................................Paraceroglyphus

 21. External vertical setae present; bases of internalvertical setae separate; coxal setae I-III always conoidal ..........................................................................22.

External vertical setae absent; bases of internal verticalsetae contiguous; coxal setae I-III filiform or conoidal ....................................................................23.

 22. Tarsus I with 9 setae (pl" present at levelof solenidion omega or more apical) ...................................................................Sancassania(=Caloglyphus)

Tarsus I with 8 setae (pl" absent) .................................................Rhizoglyphus

 23. Gnathosoma deeply cleft into a V-shape; dorsalsetae in the form of very large spines; conoidal coxal setae elongate, somewhatspine-like; 1 species from Hymenoptera; Mexico .................................................................Konoglyphus

Gnathosoma not deeply cleft; dorsal setae usually shortand filiform; conoidal coxal setae small ........................................................................................24.

24. Tibiae I-II much longer than corresponding genua; tarsusI with 9 setae (pl" present); phoretic on fleas or millipedes .............................................................Viedebanttia

Tibiae I-II similar in length or only slightly longer thancorresponding genua; tarsus I with 8 setae (pl" absent"); on awide variety of insects .....................................Schwiebea

 

 

 

 

 

 

Note: There are a number of unnamed genera in this familyoccurring in North America and elsewhere, mostly associated with fungi,Coleoptera, and Hymenoptera.

Prepared by B.M. OConnor.

Revised August 1998