Parasitiformes

Mesostigmata

Parasitina

Parasitidae - numerous genera recognized by various authors

 

Diagnosis.  Yellowish, brown, to dark brown mites; well armored and sometimes hypertrichous.  Females with separate podonotal and opisthonotal shields or holodorsal shield (lines of fusion typically visible); males with holodorsal shield.  Peritrematal shield fused to dorsal shield throughout its length; ventrianal shield extensive and typically fused to dorsal and peritrematal shields.  Female with large sternal shield bearing 3 pairs of setae (st1-3) and 2 pairs of lyrifissures (stp1-2); presternal platelets usually present; metasternal shields large, flanking acuminate genital shield, and bearing st4, stp3; mesogynial shield subtriangular to pentagonal or 3-5 acuminate, and always with mucronate apex and bearing 1 pair of setae; covering large, toothed endogynium.  Tarsus I with or without claws.  Tarsus IV without setae av4 and pv4 or an intercalary sclerite.  Unpaired, postanal seta usually present in all stages.  Chelicerae chelate-dentate, serrate, or rarely snapping; movable digit without excrescences, but arthrodial brush sometimes present in males.  Tectum mucronate, acuminate-trifurcate to denticulate, rarely bifurcate or with subdorsal median tine.  Tritosternal laciniae separate; base columnar.  Palp genu with 6 setae; subcapitular gutter typically broad, with 10 or more rows of denticles; corniculi simple, horn-like in females.  Males fully armored, with genital opening at base of tritosternum; chelicerae and corniculi sexually dimorphic, male movable digit with groove-like spermatotreme, corniculi bifurcate; femora, genua and tibia IV with ventral spurs.

 

Similar taxa.  The large metasternal shields of parasitids could be confused with the latigynial shields of some Trigynaspida, but careful checking of the sternal setae will avoid this confusion, e.g. st4 is on the metasternal and st5 on the mesogynial shield in Parasitidae, but trigynaspid latigynial shields often have several setae and their mesogynial shields are typically nude.  Veigaiidae (Dermanyssina) somewhat resemble parasitids superficially, but have very different dorsal and ventral shields.

 

Ecology & Distribution.  Parasitids are one of the dominant families of soil mesostigmatans in the Northern Hemisphere, especially the members of the Pergamasinae, but are less common on the Gondwanan continents outside of pastures and other disturbed habitats.  Many species (typically Parasitinae) are associated with carrion, dung or nests and are phoretic on beetles or flies as deutonymphs (with 2 subequal dorsal shields and a badge-shaped intercoxal shield).

 

Australian Collections.

Parasitus Latreille

           coleoptratorum (Linnaeus) (Acarus)

           flavolimbatus (Koch) (Gamasus)

           womersleyi Nozza (Parasitus)

                       cunicularis Womersley (Eugamasus)

Pergamasus Berlese

           barbarus (Berlese) (Gamasus)

           longicornis (Berlese) (Gamasus)

           quisquiliarum (Canestrini & Canestrini) (Gamasus)

Phityogamasus Juvara-Bals & Athias-Henriot

           primitivus (Oudemans) (Parasitus)

Phorytocarpais Athias-Henriot

           americanus (Berlese) (Gamasus)

           fimetorum (Berlese) (Gamasus)

Rhabdocarpais Athias-Henriot

           cunicularis (Womersley) (Eugamasus)

 

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.

Gilyarov MS & Bregatova NG (eds)  1977.  Handbook for the Identification of Soil-inhabiting Mites, Mesostigmata.  Zoological Institute of the Academy of Sciences: Petrograd [In Russian]

Johnston DE.  1982.  Mesostigmata.  In: Parker, S.P. (ed.)  Synopsis and classification of living organisms.  McGraw-Hill, New York, p. 112-116.

Krantz GW.  1978.  A Manual of Acarology.  OSU Bookstores: Corvallis.

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

Micherdzinski, W. 1980. Eine Taxonomische Analyse der Familie Macronyssidae Oudemans, 1936. I. Subfamilie Ornithonyssinae Lange, 1958 (Acarina, Mesostigmata). (Polska Akademia Nauk, Warsaw and Cracow). pp 264.

Walter DE and Proctor HC.  1999.  Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford.