| 1 | Coxae fused to ventral body forming coxal fields. Tritosternum and lateral peritremes absent (in deutonymphs of Astigmata reduced gnathosoma sometimes looks like tritosternum) | |
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- | Coxae free. Tritosternum and lateral peritremes usually present; gnathosoma not reduced. (Parasitiformes: Mesostigmata) | |
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2(1) | Posterior ventral region with suckers and conoids organized in attachment organ. Suckers and conoids of attachment organ may be variously reduced but at least 1 pair present. Chelicerae always absent. Gnathosoma variously reduced, non-functional. Palpal solenidia (if present) longer than free palpomeres. (Astigmata, heteromorphic deutonymph) | |
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- | Posterior ventral region without attachment organ; if suckers present then only 1 pair (some adult Astigmata). Chelicerae present, although sometimes modified. Functional gnathosoma present at least in female. Palpal solenidia usually shorter than free palpomeres, if longer, then chelicerae present | |
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3(2) | Attachment organ vestigial, less than 1/5 of body width, with only 1-2 pairs of distinct suckers (Astigmata, inert heteromorphic deutonymph). Gnathosomal remnant represented by 2 small glabrous palpomeres. Idiosomal setae, except scx, absent. Coxal apodemes III-IV absent. Legs vestigial, conical in shape, podomeres fused. Leg I with only a single solenidion, other legs glabrous. In nests of megachilid bees. (Chaetodactylus) | |
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- | Attachment organ well-developed, usually distinctly exceeding 1/5 of body width, with at least 2 pairs of suckers (ad1+2 and ad3) and 2 pairs conoids (ps1 and ps2) (Astigmata, phoretic heteromorphic deutonymph) | |
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4(3) | Solenidion omega1 situated on tibia I close to solenidion phi. Legs III-IV flexed at trochanter-femur articulation and directed anteriorly in repose. Tarsi III-IV with medial articulation; genu III-IV very short, distinctly shorter than corresponding femur and tibia. Vertical setae ve and vi absent | |
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- | Solenidion omega1 situated on tarsus I. Legs III-IV posteriorly or laterally directed in repose. Tarsi III-IV entire, without medial articulation; genu III-IV not distinctly shorter than corresponding femur and tibia. At least one pair of vertical setae usually present | |
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5(4) | Leg IV with pretarsal empodial claw absent; claw III present. Leg IV often smaller than leg III, with some fusion of podomeres and usually with one or more long apical setae | |
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- | Leg IV with pretarsal empodial claw present; if absent, then empodial claw III also absent. Leg IV generally similar in form to leg III | |
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6(5) | Solenidion omega3 placed closely to solenidion omega1, usually in basal half of tarsus. Coxal apodemes III fused together, to apodemes of coxal fields IV or to median apodeme, rarely free; ocelli present on apex of propodosoma with separate pigment spots or widely separated, or ocelli absent | |
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- | Solenidion omega3 apical. Coxal apodemes III-IV ending freely. Ocelli absent | |
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7(6) | Propodosoma completely covered by propodosomal shield. Setae scx filiform. Setae ve filiform, short. Pretarsal claws simple | |
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- | Propodosomal shield, if present, covers only part of propodosoma. Setae scx rod-like. Setae ve represented only by alveoli. Pretarsal claw usually strongly hooked | |
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8(5) | Empodial claws arising from membranous ambulacra. Coxal fields III closed but not fused to each other medially; posterior median ventral apodeme absent; ocelli present, widely separated | |
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- | Empodial claws arising directly from tarsal apices. Other characters variable | |
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9(8) | Coxal apodemes III-IV ending freely; all coxal fields completely open; propodosomal ocelli absent | |
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- | Coxal apodemes III-IV usually fused medially; if free, then posterior apodemes II fused with apodemes III, or propodosomal ocelli present | |
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10(2) | Chelicerae chelate-dentate, not fused with each other or with subcapitulum. Movable digit chelate, if modified, then chelicerae not fused and palp with long terminal solenidion and elongate eupathidial seta. Lateral opisthosomal glands present (Astigmata, feeding stages) | |
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- | Chelicerae modified: movable digit styletiform or hooklike. Sometimes chelicerae fused forming a stylophore, which also can be fused ventrally with subcapitulum forming a capsulate gnathosoma. Terminal solenidion of palp shorter than free palpomeres. Lateral opisthosomal glands absent (Prostigmata) | |
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11(10) | Chelicerae non-chelate, fixed digit usually with numerous teeth. Palp usually with long terminal solenidion and at least one elongate eupathidial seta, normal setae absent; palp usually reflexed outward; genital papillae disassociated from genital opening, represented by large ring-like (sometimes irregularly shaped) areas on external cuticle | |
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- | Chelicerae usually chelate, with few teeth. Palp with short terminal solenidion (sometimes long) and normal setae; reflexed inward. Genital papillae placed under valves of genital opening, cylindrical or bell-shaped | |
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12(11) | External vertical setae (ve) absent; pretarsi with long and thin condylophores, or condylophores fused or absent. Males without sucker-like setae on tarsus IV or para-anal suckers | |
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- | External vertical setae (ve) present, or if absent, then pretarsi with short, strong condylophores. Male with 2 sucker-like setae on tarsus IV and usually with para-anal suckers | |
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13(12) | Tarsi with setae e I-IV usually spine-like (rarely filiform), shorter than filiform f. Unguinal setae (u and v) usually larger and stouter than proral setae (p and q). External vertical setae (ve) present or absent | |
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- | Tarsi with both tectal setae (e and f) filiform, similar in length. Unguinal setae (if present) shorter than proral setae (p and q), the latter spine-like or enlarged and claw-like. External vertical setae (ve) present | |
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14(13) | Body outline round, length similar to width; some dorsal setae often heavily pectinate or plumose, or all short and simple; proral (p and q) and unguinal (u and v) setae filiform, similar in form | |
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- | Body distinctly longer than wide; dorsal setae filiform, nude; tarsi with proral setae (p and q) enlarged and claw-like, unguinal setae (u and v) reduced or absent | |
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15(12) | Supracoxal gland opening larger than distance between setae vi, placed on distinct oval sclerite above legs I. Female pretarsus with paired elongate condylophores; male condylophores modified into sucker-like organ at base of pretarsus | |
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- | Supracoxal gland opening smaller than distance between setae vi. Sucker-like organ on male pretarus absent | |
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16(15) | Prodorsal sclerite absent; internal vertical setae (vi) situated about half-way between anterior edge of propodosoma and scapular setae; with a pair of distinct ocelli in propodosomal region; coxal apodemes I fused medially with coxal apodemes II closing coxal fields I in both sexes | |
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- | Prodorsal sclerite well-developed; internal vertical setae (vi) at anterior edge of propodosoma or absent; ocelli present or absent; coxal apodemes I not fused distally with apodemes II, coxal fields I open | |
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17(16) | Empodial claws present; condylophores usually fused into a V-shaped sclerite or a more elongate sclerite in base of ambulacral stalk; tibiae I-II with 1-2 ventral setae; male with all traces of genital (g) and setae 4a absent | |
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- | Empodial claws and condylophores absent; tibiae I-II with 1 ventral setae. Male with filiform setae 4a. In nests of stingless bees (Meliponini) | |
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18(10) | Pretarsal empodium (median claw) membranous with setules. 1 pair of prodorsal trichobothria. Peritremes and stigmatal opening absent (not to be confused with podocephalic canal). Palp tibia without claw-like seta, palp tarsus terminal | |
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- | Pretarsal empodium claw-like, if membranous then nude. 0-2 pairs of prodorsal trichobothria. Peritremes and stigmatal opening usually present. Palp variable | |
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19(18) | Tibial solenidion, if present, not recessed into a pit. Dorsal opisthosomal trichobothria may be present | |
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- | Tibial solenidion recessed into a pit. Dorsal opisthosomal trichobothria absent | |
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20(18) | Pretarsal empodium of legs II-III membranous, nude. Palp very small, with two non-articulating palpomeres, extending to or slightly beyond subcapitular extremity. Palp tibia without enlarged claw-like seta, palp tarsus terminal or ventral (Heterostigmata) | |
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- | Pretarsal empodium of legs II-III claw-like. Palp distinct, with more than two articulating palpomeres, extending beyond subcapitular extremity. Palp tibia with enlarged, dorsal claw-like seta; palp tarsus displaced ventrally (thumb-claw process) | |
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21(20) | Pretarsal empodium rayed with tenent hairs. Chelicerae fused together and with subcapitulum. Peritremes arch-like, chambered, placed on dorsal surface of gnathosoma. Palp tarsus with 1-2 comb-like setae | |
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- | Pretarsal empodium nude. Chelicerae free, not fused with subcapitulum. Peritremes, if present, located between cheliceral bases, not chambered and not arch-like. Palps without comb-like setae. Hexapod parasites, attached to host cuticle (Parasitengona, larva) | |
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22(21) | Claparede's organ absent. Tarsi with 3 claws (2 pretarsal claws and empodium). Two pairs of prodorsal trichobothria. Coxal fields I and II distinctly separated. No distinct reticulate pattern on postero-apical corner of coxa III | |
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- | Claparede's organ present. Tarsi with 1 empodial claw (pretarsal claws absent). One pair of prodorsal trichobotra. With distinct reticulate pattern on postero-apical corner of coxa III | |
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23(20) | Tarsus II with 8 setae. Female: First hysterosomal tergite divided into medial and 2 lateral plates; leg I with 5 podomeres (tibia and tarsus free); with a pair of internal sacs between legs III and IV (sporothecae). Male without genital capsule | |
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- | Tarsus II with fewer than 8 setae. Female: first hysterosomal tergite not divided; leg I with 4-5 podomeres; without sporothecae between legs III and IV (may be present in other places). Male genital capsule present | |
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24(23) | Pharyngeal musculature not subdivided or indistinct in female. Male gnathosoma well-developed | |
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- | Pharyngeal musculature subdivided into large anterior part and 1 or 2 separate posterior parts. Male gnathosoma well-developed | |
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25(24) | Podonotal shield completely covers propodosoma, forming a "roof" with striate margin | |
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- | Podonotal shield does not cover propodosoma, if covering then "roof" without striate margin | |
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26(24) | Leg IV of female with separate femur and genu, often pretarsus with claws and membranous empodium. Leg IV of male with 5 podomeres | |
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- | Leg IV of female, when present, with fused femur and genu, pretarsus without claw and empodium. Leg IV of male, when present, with 3-5 podomeres | |
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27(26) | Leg IV present in adults, with 3 (females) or 3-4 (males) podomeres, attenuate in female | |
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- | Leg IV usually absent in adults, if present, with 5 podomeres | |
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28(1) | Movable digit of female chelicera with several pectinate or dendritic, brush-like or filamentous excrescenses (occasionally excrescenses also present at base of digit). Epigynial shield absent or very reduced, non-functional (mesogynial shield); latigynal shields present in female (not to be confused with metasternal shields which normally bear pores P3 and setae ST4 or sternogynial shields with pores P3 or without). Spermatodactyl and distinctive spurs on legs absent in male. Pretarsus I without claws or pulvillus. Unpaired postanal seta absent (figured in Calaenosthanus trigonophilus) (Trigynaspida) | |
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- | Movable digit of female chelicera without excrescenses. Often excrescenses present at base of digit. Epigynial shield present, functional; latigynal shields absent in female. Spermatodactyl usually present in male (sometimes coalescent with movable digit); spurs on legs present or absent. Pretarsus I with or without claws or pulvillus. Unpaired postanal seta present (Monogynaspida) | |
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29(28) | Anal shield of female oval, separated from ventral shield by area of soft cuticle. Ventromarginal shields not fused with peritrematal plate. Mesogynial shield more than 1/2 of length of latigynal shields. Femur II with 9 setae. Corniculi thin, almost seta-like | |
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- | Anal shield of female fused with ventral shield (if separate, then triangular, not isolated by soft cuticle and completely flanked by ventromarginal shields). Ventromarginal shields fused with peritrematal plate. Mesogynial shield usually less that 1/3 of length of latigynal shields. Femur II with 10 setae. Corniculi strong, not seta-like | |
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30(28) | Coxae I nearly touching each other, partially overlapping or covering tritosternal base. Foveolae pedale usually present (Uropodina). Pilus dentilis on fixed digit bifurcated (not blunt, cylindrical) | |
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- | Coxae I separated, not overlapping or covering tritosternal base. Foveolae pedale absent. Pilus dentilus variable | |
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31(30) | Female epigynial shield well-sclerotized, triangular, flanked by large metasternal shields. Male spermatodactyl coalesced with movable digit. Palpal apotele trifid. Males often with highly developed spurs and apophyses on leg II (Parasitina) | |
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- | Anterior part of female epigynial shield rounded or truncate (if pointed than shield weakly sclerotized). Male spermatodactyl free. Palpal apotele bifid or trifid. Apophyses and spurs present or absent on male legs (Dermanyssina)... 32 |
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32(31) | One or two brushes at base of movable digit. Tarsus I without claw or sucker. Peritreme forming a loop, entering stigma posteriorly. In female, accessory genital sclerites well-developed | |
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- | Arthropodial process at base of movable digit not brush-like. Other characters variable | |
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33(32) | Epigynial shield rounded or pointed posteriorly, sometimes fused with ventral or rarely with anal shield. Anal shield usually triangular | |
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- | Epigynial shield truncate or weakly convex posteriorly, sometimes abutting broad ventrianal shield (if genital shield is rounded posteriorly, then anal shield not triangular) | |
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34(33) | Dorsal shield of deutonymphs and adults with fewer than 20 pairs of setae. Corniculi may be divided distally. Female sternal shield usually with two pairs of setae; third pair of sternal setae (ST3) placed on adjacent platelets, soft cuticle, or rarely on sternal shield | |
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- | Dorsal shield of deutonymphs and adults with more than 20 pairs of setae. Corniculi not divided, if divided, then other sternal shield with 3 pairs of sternal setae | |