Taxonomic Position

Cohort Gamasina

    Subcohort Dermanyssiae

  Superfamily Phytoseioidea

 

Family: Blattisociidae

Subfamily Platyseiinae (formerly Ascidae, Platyseiinae)

Platyseius Berlese (including Plesiosejus Evans & Hyatt)

 

Diagnostic characters:

• Opisthonotal region of dorsal shield with 12-15 pairs of setae, but only 2-4 pairs of setae in J-series

• First pair of sternal setae (st1) distinctly shorter than third pair (st3)

• Distance between fifth and sixth rows of deutosternal denticles nearly twice that between fourth and fifth rows; tibia II with 9 setae (pd1 absent). 

• Legs II-IV with median lobe of pulvillus slender, acute or narrowly rounded; para-anal setae inserted level with or posterior to hind margin of anus, and usually longer than post-anal seta; femora I and II with 11 and 10 setae respectively (each lacking v-3);

• Anterior rostral and internal palp trochanter setae extremely long, whip-like, tapering only near tip

• Phytoseiid-type sperm access system

• Fixed cheliceral digit with a deep receptacle that receives the tip of the movable digit. 

• Usually with a long post-stigmatic arm of the peritreme extending along coxa IV

• Male lacking metasternal setae.

 

Key to females of genera of Platyseiinae

1.     Opisthonotal region of dorsal shield markedly hypotrichous, with only 5 pairs of setae (Z1, Z4, Z5, S4, J5); sternal setae st4 in soft cuticle; with anal shield; median lobes of pulvillus of legs II-IV blunt; ........................ Cheiroseiulus

-     Opisthonotal region of dorsal shield with 12-15 pairs of setae; with metasternal plates bearing st4 and ventrianal shield; median lobes of pulvillus of legs II-IV acute; ..................................................2

2.   Opisthonotal region of dorsal shield with 2-4 pairs of setae in J-series; first pair of sternal setae (st1) distinctly shorter than third pair (st3); distance between fifth and sixth rows of deutosternal denticles nearly twice that between fourth and fifth rows; tibia II with 9 setae (pd1 absent) ......................... Platyseius

-     Opisthonotal region of dorsal shield with 5 pairs of setae in J-series; 1st and 3rd pairs of sternal setae subequal in length; distance between 5th and 6th rows of deutosternal denticles similar to that between 4th and 5th rows; tibia II with 10 setae (pd1 present)..........................................Cheiroseius

 

Ecology & Distribution. Less than 20 described species and numerous undescribed species.  Mites of the genus Platyseius are found in moist soils and fully aquatic habitats; some are known to feed on Culex egg rafts.

 

References

Evans, G. O. and Hyatt, K. H. 1960. A revision of the Platyseiinae (Mesostigmata: Aceosejidae) based on material in the collections of the British Museum (Natural History). Bulletin of the British Museum (Natural History) Zoology 6 (2) : 27-101.

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.

Hinton, H.E.  1971.  Plastron respiration in the mite Platyseius italicus.  Journal of Insect Physiology 17: 1185-1199.

Karg W. 1993. Acari (Acarina), Milben. Parasitiformes (Anactinochaeta). Cohors Gamasina Leach. Raubmilben. (Second Edition). Die Tierwelt Deutschlands 59: 1-523.3.

Kitching RL & Callaghan C. 1982. The fauna of water-filled tree holes in box forest in south-east Queensland. Australian Entomological Magazine 8: 61-70.

Krantz GW. 1962. Acari. Free-living Mesostigmata. II. – The family Aceosejidae. Parc National de la Garamba. – Mission H. de Saeger 34: 3-29.

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, E.E.  2003.  Observations on mites of the subfamily Platyseiinae, with descriptions of two new species of Platyseius from North America (Acari: Mesostigmata: Ascidae).  pp. 155-182 in Smith, Ian M. [Ed.]. An acarological tribute to David R. Cook. Indira Publishing House, West Bloomfield.