Mesostigmata, Canestrini, 1891

Alatawi, Fahad Jaber, Kamran, Muhammad & Mirza, Jawwad Hassan, 2018, Mesostigmatic mites (Acari: Mesostigmata) of Saudi Arabia (excluding Phytoseioidea), new records and a key to the known species, Zootaxa 4388 (3), pp. 373-394 : 387-390

Key to the females of Mesostigmata from Saudi Arabia, excluding the Phytoseioidea

1. Oviporus covered by single large epigynal shield bearing six to many setae, tarsus of leg IV with minimum of 20 setae, dorsal shield with a pair of posterior horn-like processes bearing setae........................................................................................... Family Sejidae , Genus Sejus Koch , S. australis Hirschmann & Kaczmarek

- Oviporus covered by single epigynal shield bearing zero to one pair of setae or shield absent, tarsus of leg IV with maximum of 18 setae, dorsal shield usually without posterior horn-like processes .. Suborder Monogynaspida ....................... 2

2. Epigynal shield of female flask or wedge shaped or subtriangular, often extending into the opisthogastric region and bearing setae st5, adults with one to two dorsal shields lacking marginal shields or their platelets, peritremes typically linear, sometimes reflexed anteriorly or posteriorly, femora IV typically with six setae ... Cohort Gamasina........................ 3

- Epigynal shield of female oval, subtriangular or tongue, usually nude and partially or entirely enclosed by fused sternal-endopodal-ventral shield bearing sternal setae 1-5 (st5 rarely on separate shield that may be partially fused with epigynal shield), adults with one to many dorsal shields, marginal shields or platelets usually present, peritremes usually sinuous, sometimes on hornlike projections, femora IV with seven or eight setae … Cohort Uropodina................................... 48

3. Genu III and IV each with ten setae, female epigynal/genital shield lacking expanded hyaline rim anteriorly.................................................................................................Family Zerconidae … 4

- Genu III and IV usually with nine or fewer setae, female epigynal/genital shield with expanded hyaline rim anteriorly...... 5

4. Peritremal shield with three setae................................Genus Parazercon Trägårdh , P. sarekensis Willmann

- Peritremal shield with two setae........................................Genus Prozercon Sellnick , P. kochi Sellnick

5. Female with sternal setae st4 on large metasternal plates flanking an anteriorly acuminate epigynal shield antero-laterally … Family Parasitidae ..................................................................................... 6

- Female usually with sternal setae st4 on relatively small metasternal plates or on soft integument or on posterolateral corners of sternal shield, epigynal shield anteriorly not acuminate, otherwise ... Subcohort Dermanyssiae........................ 10

6. Dorsal shield setae j5, j6, z5 similar in form Subfamily Pergamasinae ............................................................................................. Genus Pergamasus Berlse , P. (Pergamasus) longicornis (Berlese)

- Dorsal shield setae j5, j6, z5 dissimilar in form … Subfamily Parasitinae .......................................... 7

7. Lateral seta of palp femur (al) entire....................................................................... 8

- Lateral seta of palp femur (al) bifid, setae z5 thicker than j5 … Genus Parasitus Latreille. ........................... 9

8. Seta z5 of dorsal hexagon thickened, associated with insects ( Musca domestica )............................................................................................... Genus Gamasodes Oudemans , G. buettikeri Samšiňák

- Seta z5 simple, associated with carrion beetle................. Genus Poecilochirus Canestrini , P. necrophori (Vitzthum)

9. Sternal shield with heavy striations; st1 forked distally, arising from small platelets... P. consanguineus Oudemans & Voigts

- Sternal shield without striations; st1 simple................................................ P. fimetorum (Berlese)

10. Female sternal shield usually fused with metasternal plates includes fourth pair of sternal setae (except Halolaelapidae ), female epigynal shield separate from ventrianal or anal shield ... Superfamily Rhodacaroidea .............................. 11

- Female sternal shield not fused with metasternal plates leaving fourth pair of sternal setae free on soft integument, female epigynal shield expanded into genito-ventral/ventrianal shield..................................................... 21

11. Seta st4 on metasternal platelet or on soft integument........................................................ 12

- Seta st4 on sternal shield............................................................................... 13

12. Endopodal platelets fused with the sternal shield........................ Genus Zygoseius Berlese , Z. furciger (Berlese)

- Endopodal platelets not fused, separate from the sternal shield......... Family Halolaelapidae , Genus Saprolaelaps Leitner

13. Palp tarsal claw two-tined; tibia I with five dorsal setae; genu and tibia IV with six to eight setae, including four and three dorsal setae respectively................. Family Digamasellidae , Genus Dendrolaelaspis Lindquist , D. baloghi Hirschmann

- Palp tarsal claw three-tined; tibia I with six dorsal setae; genu and tibia IV with nine to ten setae, including five and four dorsal setae respectively..................................................................................... 14

14. Podonotal and opisthonotal shields usually separate, scleronoduli usually present, usually with desclerotised bands of punctate integument along posterior margin of podonotal, anterior margin of opisthonotal, anterior margin of sternal, posterior margin of genital and anterior margin of ventrianal shields ... Family Rhodacaridae ...................................... 15

- Podonotal and opisthonotal shields usually separate, scleronoduli always absent, usually without desclerotised bands punctate integument ... Family Ologamasidae ...................................................................... 19

15. Ventrianal shield>1.8 times as long as wide, encompassing only one to two pairs of preanal setae; podonotal shield with 16 pairs of setae...................... Genus Protogamasellopsis Evans & Purvis , P. zaheri Abo-Shnaf, Castilho & Moraes

- Ventrianal shield ≤1.6 times as wide as long, encompassing more than four pairs of preanal setae; podonotal shield with ≥17 pairs of setae........................................................................................ 16

16. Scleronoduli absent, cheliceral arthrodial process a short coronet like fringe or elongate three tined, dorsal setae pilose..................................................................................... Genus Pennarhodeus Karg

- Podonotal shield with three or four scleronoduli............................................................ 17

17. Podonotal shield with three scleronoduli.................................................................. 18

- Podonotal shield with four scleronoduli............................... Genus Rhodacarellus Willmann , R. citri Fouly

18. Fixed cheliceral digit with at least nine teeth; podonotal shield with V-shaped line posterior of setae j4, z3 and s2 .............................................. Genus Multidentorhodacarus Karg , M. aegypticus Abo-Shnaf, Castilho & Moraes

- Fixed cheliceral digit with at most six teeth; podonotal shield with or without V-shaped line posterior of setae j4, z3 and s2... ........................................................... Genus Rhodacarus Oudemans , R. roseus Oudemans

19. Dorsal shield not fused with ventrianal shield, pretarsus I sessile ... Genus Sessiluncus Canestrini , S. aegypticus Nasr & Afifi

- Dorsal shield fused with ventrianal shield, pretarsus I pedunculated ... Genus Gamasiphis Berlese. .................... 20

20. Seta j3 about 1.4 times as long as distance between its base and base of j4 ..................... G. denticus Hafez & Nasr

- Seta j3 about 0.8 times as long as distance between its base and base of j4, seta ZV2 about 1.2 times as long as distance between its base and base of ZV3......................................................... G. pulchellus Berlese

21. Arthrodial process at base of moveable digit of chelicerae with one or two plumose or filamentous process or with a brush, peritremes generally looped, tarsus I usually without claws, females with a pair of accessory sclerites beneath the lateral margins of epigynal shield ... Family Macrochelidae ................................................................ 22

- Arthrodial process, if present, at base of moveable cheliceral digit with atmost a fringed coronet but without distinct filamentous or brush like process, peritremes not looped, tarsus I with claws, females without a pair of accessory sclerites beneath the lateral margins of epigynal shield........................................................................ 28

22. Setae j1 present on an anterior projection of the dorsal shield......... Genus Holostaspella Berlese , H. bifoliata (Trägårdh)

- Dorsal shield without anterior projection, regularly rounded ... Genus Macrocheles Latreille. ........................ 23

23. One to three pairs of postgenital apodemes present between genital and ventrianal shields, ventrianal shield with rounded anterior margin............................................................................. M. opacus (Koch)

- Postgenital apodemes absent between genital and ventrianal shields, ventrianal shield with straight anterior margin, abutting the genital shield..................................................................................... 24

24. Setae j1 smooth and spine-like.......................................................................... 25

- Vertical setae j1 always pilose/plumose or serrated.......................................................... 26

25. Genu IV with seven setae; larger species, idiosoma> 555-740µm............................. M. subbadius (Berlese)

- Genu IV with six setae; smaller species, idiosoma 440-510µm................................ M. merdarius (Berlese)

26. All lateral and marginal setae (in S -s and r setal series) simple and smooth.......................... M. glaber (Müller)

- All or most lateral and marginal setae (in S -s and r setal series) serrate or plumose................................. 27

27. All lateral and marginal setae including plumose, setae j5 simple, smooth and needle-like... M. muscaedomesticae (Scopoli)

- Three pairs of lateral and marginal setae (s2, s4, r4) simple, smooth and needle-like................. M. mammifer Berlese

28. Tarsus II usually with one to two of the distal setae enlarged into stout spines, female with genitiventral shield closely bordered by an anal shield or with peritremetic exopodal shields extending posteriorly beyond coxae IV to fuse with metapodal platelets, spur like distal setae on tarsus II present, genu and tibia I with five dorsal setae, palp apotele three tined....................................................Family Pachylaelapidae , Genus Onchodellus Berlese , O. aegypticus (Hafez & Nasr)

- Tarsus II without distal spinose structures, female with epigynal shield separate from a ventrianal or anal shield.......... 29

29. Female sternal shield with one or typically two pairs of setae, sternal setae St3 often on adjacent platelets or on soft cuticle, rarely on sternal shield, opisthonotum without J5 and marginal setae (R) ... Family Ameroseiidae ..................... 30

- Female with zero to typically three pairs of sternal setae on sternal shield, opisthonotum with setae J5 and usually with one or more marginal (R) setae............................................................................... 32

30. Genu III with nine setae, including one posterolateral seta, cheliceral fixed digit with three denticles, setae Z5 and S5 progressively narrowed towards their tips, lanceolate; vertex with finely serrate horn-like process on each side and between bases of j1; setae j5 thinner and shorter than j6; anal shield with smaller suboval anus situated in posterior portion of the shield..................................................................... Genus Ameroseius Berlese , A. lidiae Bregetova

- Genu III with ten setae, including two posterolateral setae, fixed cheliceral digit with four prominent denticles ... Genus Kleemannia Oudemans. ................................................................................... 31

31. Epigynal shield with inverted U-shaped sculptural structure on anterior surface, the structure smooth and well sclerotised............................................................................ K. parplumosa Nasr & Abou-Awad

- Epigynal shield with simple sculpture on anterior surface, smooth or reticulate, setae j5 apparently shorter than J2 and J4, with tips reaching between bases of j5 and j6................................................ K. pseudoplumosa (Rack)

32. Female with third pair of sternal poroids on posterolateral corners of sternal shield with St4 usually on soft cuticle, moveable cheliceral digit usually bidentate ... Family Ascidae .......................................................... 33

- Female with third pair of poroids of sternal shield associated with sternal setae St4 usually on metasternal plates or on soft cuticle, moveable cheliceral digit with zero to many teeth, usually tridentate......................................... 37

33. Dorsal shield of deutonymph and adult entire, lateral incisions of deutonymphal shield retained or lost in adults, opisthonotal region of dorsal shield with four pairs of marginal setae (S2 absent) ... Subfamily Arctoseiinae ....................... 34

- Dorsal shield of deutonymph and adult completely divided in two, opisthonotal region of dorsal shield with five pairs of marginal setae (S2 present) ... Subfamily Ascinae .............................................................. 35

34. Genu II with ten setae, genu IV with seven setae, tibia III with seven setae......... Genus Arctoseius Thor , A. bilinear Nasr

- Genu II with 11 setae, genu IV with nine setae, tibia III with seven setae..................... Genus Neojordensia Evans

35. Opisthonotal shield with setae Z4 and S5 usually approximal and inserted together on pair of prominent posterolateral tubercles, podonotal shield lacking setae................................ Genus Asca von Heyden , A. aphidioides Linneaus

- Opisthonotal shield with setae Z4 and S5 well separated not borne on strong tubercles, podonotal shield with setae z1 present.................................................................................................... 36

36. Podonotal shield with transverse line extending completely across surface at level of setae z6, opisthonotal shield with similar line at level of setae J1, para-anal setae close to anterior margin of anus than posterior margin, genu IV with eight setae, tibia IV with nine setae.............................................................. Genus Protogamasellus Karg

- Dorsal shield without transverse lines extending completely across surface, para-anal setae inserted closer to posterior margin of anus than to anterior margin, genu IV with nine setae, tibia IV with ten setae....................................................................................... Genus Gamasellodes Athios-Henriot , G. insignis (Hirschmann)

37. Genital shield truncate or weakly convex posteriorly and either narrowly separated from or abutting a ventrianal shield or widely separated from an anal shield that is round or oval but not inversely subtriangular, fixed cheliceral digit with pilus dentilis modified to hyaline flap, moveable cheliceral digit with a pointed mucro on mid ventral face.......................................................Family Melicharidae , Genus Proctolaelaps Berlese , P. gizanesis Abo-Shnaf & Moraes

- Genital shield broadly or narrowly rounded posteriorly, usually widely separated from inversely subtriangular anal shield, fixed cheliceral digit with pilus dentilis not modified to hyaline flap............................................ 38

38. Chelicerae whiplike, styliform; cheliceral digits minute, chelate; corniculi membranous, indistinct................................................................................. Family Dermanyssidae , Genus Dermanyssus Dugès

- Chelicerae variously produced dentate or edentate but not styliform, corniculi variously developed, membranous or strongly sclerotised.......................................................................................... 39

39. Chelicerae elongate, edentate, corniculi membranous, palptrochanter with a raised medioventral keel.....................................................................Family Macronyssidae , Ornithonyssus Sambon , O. bacoti (Hirst)

- Chelicerae variously developed, dentate or edentate, corniculi strongly sclerotised, palptrochanter without a raised medioventral keel............................................................................................ 40

40. Fixed digit of chelicerae absent, only two pairs of hypostomatic setae present...................................................................... Family Varroidae , Genus Varroa Oudemans , Varroa destructor (Anderson & Trueman)

- Fixed digit of chelicerae present, three pairs of hypostomatic setae present ... Family Laelapidae ...................... 41

41. Sternal shield of female deeply concave, almost crescent shaped....................... Genus Hyperlaelaps Zachvatkin

- Sternal shield of female weakly concave.................................................................. 42

42. Fixed digit of chelicerae in female with pilus dentilis well developed with expanded/inflated basal half................................................................................................. Genus Androlaelaps Berlese

- Fixed digit of chelicerae in female with pilus dentilis setiform, small without expanded/inflated basal half.............. 43

43. Genito-ventral shield of female with one pair of setae, genital shield distinctly apart from the anal shield............... 44

- Genito-ventral shield of female with one to three pairs of setae, all on the edges of the shield, the genital shield reaching to or abutting with the anal shield............................................................................ 46

44. Dorsal shield setae acicular, hair like............................................... Genus Gaeolaelaps Trägårdh

- Dorsal shield setae basally expanded or spatulate........................................................... 45

45. Corniculi long, their tips reaching to the middle or to the anterior margin of the palp femur............................................................................................. Genus Stratiolaelaps , S. scimitus Womersley

- Corniculi short with tips not reaching to the middle or to the anterior margin of the palp femur. Genus Cosmolaelaps Berlese

46. Flagelliform setae present on femora of leg II and III, several pairs of dorsal shield markedly longer than the rest......................................................................................... Genus Hypoaspis Canestrini

- Flagelliform setae on legs absent........................................................................ 47

47. Genital shield with " ^ " shaped structure, the central part of shield with nine to ten large cells, dorsal shield setae nearly scimeter shaped with small knob at their base, palp apotele three tined.. Genus Laelaspis Berlese , L. pennatus Joharchi & Halliday

- Genital shield without " ^ " shaped structure, dorsal shield setae acicular shape with small knob at their base, palp apotele two tined......................................................................... Genus Gymnolaelaps Berlese

48. Coxae of leg I normally produced, not covering the base of tritosternum, pedofossae absent................................................ Family Polyaspididae , Genus Polyaspis Berlese , P. (Polyaspis) madagascarensis Kontschán & Starý

- Coxae of leg I usually widened and flattened, covering partially or entirely the base of tritosternum, pedofossae often present, sometime absent ... Superfamily Uropodoidea .............................................................. 49

49. Chelicerae without internal sclerotised node, setae h1 typically long and setiform, female genital shield located between coxae II-IV … Family Uropodidae ............................................................................ 50

- Chelicerae with distinct internal sclerotised node associated with levator tendon................................... 51

50. Marginal setae one or two pairs.................. Genus Centrouropoda Berlese , C. almerodai Hiramatsu & Hirschmann

- Numerous marginal setae present........................................................... Uropoda Latreille

51. Internal malae of hypostome simple, without marginal fimbriations or distal moustache like excrescences, dorsal shield of adults often notched marginally ... Family Trematuridae ...................................................... 52

- Internal malae with short marginal fimbriations and/or with elaborated distal moustache like excrescences, fixed cheliceral digit typically with a rounded or acuminate apical finger that extends well beyond the moveable digit, peritremes well developed and often elaborated to form distinctive serpentine patterns............................................... 53

52. Tectum denticulate, tapering, conrniculi divided, often with one to two pairs of elongate posterior setae............................................................................................... Genus Trichouropoda Berlese

- Tectum distally branched process, conrniculi simple, without elongate elongate posterior setae... Genus Nenteria Oudemans

53. Body ringed in hypertrophied setae which form a basket-like shape on the dorsum............................................................................................. Family Dinychidae , Genus Clausiadinychus Sellnick

- Body without hypertrophied setae forming basket shaped around the dorsum...................................................................................................Family Urodinychidae , Genus Uroobovella Berlese