Taxonomic Position

Cohort Gamasina

    Subcohort Dermanyssiae

  Superfamily Ascoidea

Family: Ascidae Voigts & Oudemans

Subfamily: Arctoseiinae

Xenoseius Lindquist & Evans 

 

Diagnostic characters:

• Arctoseiinae with tarsus I without claws

• Dorsal shield setae j1 & z1 smooth, short and blunt or barbed and variable in length; other dorsal shield setae simple (J5 sometimes barbed), none paddle-shaped; S2 present

• Tarsi II-IV each with dorso-proximal setae ad2, pd2 elongate, curved; genu III usually with 8 setae

• Female with ventrianal shield bearing 1-6 pairs of ventral setae in addition to circumanal setae.

Similar taxa not in Lucid key (see below): Arctoseiodes Willmann, Zercoseius Berlese, Arctopsis Athias-Henriot, Leioseius Berlese].

Similar taxa in key.  Arctoseius Thor, Iphidozercon Berlese, Neojordensia Athias-Henriot, Zerconopsis Hull

 

Key to Genera of Arctoseiinae & similar Ascinae

 

1.  Leg chaetotaxy reduced, maximum setation: genu II = 10, genu IV = 7, tibia III = 7, tibia IV = 7; opisthonotal region of dorsal shield usually with 4 pairs of lateral setae (S1 present, S2 usually absent); deutosternal denticular rows moderately wide, multidenticulate .................................................................. 2

 -   Leg chaetotaxy without above reductions, minimum setation: genu II = 11, genu IV = 9, tibia III = 8, tibia IV = 10; opisthonotal region of dorsal shield usually with 5 pairs of lateral setae (S2 present, S1 rarely absent); deutosternal denticular rows narrow, each with few (usually 2-6) denticles................ 5

2.  Tarsi II-IV each with dorso-proximal setae ad2, pd2 elongate, curved; genu III usually with 8 setae; female with ventrianal shield bearing 1-6 pairs of ventral setae in addition to circumanal setae................... 3

 -   Tarsi II-IV with dorso-proximal setae not elongate or curved; genu III with 7 setae (pv1 absent); female with anal shield bearing only circum-anal setae (rarely with ventral setae JV3 on shield)................. 4

3 . Tarsus I without claws; dorsal shield setae j1 & z1 smooth, short and blunt or barbed and variable in length; other dorsal shield setae simple (J5 sometimes barbed), none paddle-shaped............. Xenoseius

-    Tarsus I with claws; dorsal shield setae j1 and z1 smooth, pointed (j1 rarely paddle-shaped), variable in length; some dorsal shield setae (always s4 and Z5) paddle-shaped......................... Zerconopsis

4.  Vertex of dorsal shield strongly arched downward, setae j1 concealed from above; peritremes sharply recurved distally; dorsal shield without midlateral incisions; tarsi II-IV with 1 (al1) or 2 (al1, pl1) dorso-lateral subapical setae very slender and elongate; palp tarsus with macroseta ................... Iphidozercon

-    Vertex of dorsal shield not strongly arched downward, setae j1 visible from above; anterior extremities of peritremes not recurved; dorsal shield with or without midlateral incisions; tarsi II-IV with neither of dorso-lateral subapical setae slender and elongate; palp tarsus without macroseta.....Arctoseius

5.  Dorsal shield lacking setae z1; epistome convex and smooth or slightly denticulate; genu I with 12 setae (av2 absent), tibia II with 9 setae (ad2 absent) ................................................................................ 6

-   Setae z1 present; tectum bi- or triramous; genu I with 13 setae, tibia II with 10 setae......................... 7

6.  Dorsal shield with midlateral incisions; all r-R marginal setae on soft cuticle flanking dorsal shield; female with: first pair of sternal setae on sternal shield, genital setae and pores on soft cuticle flanking epigynial shield, anal shield bearing only circum-anal setae ...................................................... Arctopsis

-     Dorsal shield lacking midlateral incisions; r-R marginal setae on edges of dorsal shield; female with: first pair of sternal setae on jugular plates separated from sternal shield or on margin of shield, genital setae and pores on epigynial shield, ventri-anal shield incorporating metapodal plates and bearing 4-5 pairs of setae in addition to circum-anal setae ........................................................................... Neojordensia

7.   Dorsal shield lacking setae z3, J2, S1; R3, R4 on dorsal shield, others (r6, R2, R5) absent; genu and tibia I each with 12 setae (av2 absent); genu III with 10 setae, tibia III with 9 setae (pl2 present on both); genu IV with 10 setae (pv1 present) ......................................................................................... Arctoseiodes

-    Dorsal shield holotrichous, with z3, J2, S1; 10-11 pairs of marginal r-R setae on soft cuticle laterally, none on dorsal shield; genu and tibia I each with 13 setae (av2 present); genu III with 8-9 setae, tibia III with 8 setae (pl2 absent on both); genu IV with 8-9 setae (pv1 absent) ......... Leioseius

 

References

Evans EO & Till WM.  1979.  Mesostigmatic mites of Britain and Ireland (Chelicerata: Acari-Parasitiformes).  An introduction to their external morphology and classification.  Transactions of the Zoological Society of London 35 (2): 145-270.

Halliday RB, Walter DE & Lindquist EE.  1998.  Revision of the Australian Ascidae (Acarina: Mesostigmata).  Invertebrate Taxonomy 12: 1-54.

Karg W. 1993. Acari (Acarina), Milben. Parasitiformes (Anactinochaeta). Cohors Gamasina Leach. Raubmilben. (Second Edition). Die Tierwelt Deutschlands 59: 1-523.

Krantz GW. 1986. A Manual of Acarology. Second edition, 1978, emended 1986. (Oregon State University Book Stores, Corvallis, Oregon USA).

Krantz GW & Ainscough B.  1990.  Mesostigmata.  pp. 583-665, in DL Dindal (ed) Soil Biology Guide.  John Wiley & Sons: Brisbane.

Lindquist EE & Evans GO. 1965. Taxonomic concepts in the Ascidae, with a modified setal nomenclature for the idiosoma of the Gamasina (Acarina : Mesostigmata). Memoirs of the Entomological Society of Canada 47: 1-64.