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Ophionyssus
Taxonomic
Position
Cohort Gamasina
Subcohort Dermanyssiae
Superfamily
Dermanyssoidea
Family Macronyssidae
Oudemans
Ophionyssus Mégnin
Ophionyssus natricis
Gervais - the snake mite
Diagnostic
characters:
-
Grey-brown to red (when blood engorged)
or black parasitic dermanyssine
mesostigmatans with a truncate dorsal shield covering the podonotal region and
two pairs of small scutellae in the mesonotal region and a small, subcircular
pygidial shield
-
Sternal shield entire to eroded
sternal shield bearing 2 pairs of setae
-
Genital
shield dagger-shaped, nude
-
st3-5 in soft cuticle
-
Anal shield small, with 3 circumanal
setae
-
Some ventral and lateral hypertrichy
present
-
Chelicerae elongate and edentate stylets.
-
Palp genu with 6 setae, palp apotele
2-tined; corniculi membranous
-
Tritosternum
biflagellate with denticulate membranous margin
-
Dorsal shield truncate, opisthonotum exposed.
Similar taxa.
Laelapid mites are similar, but lack the expanded margins of the tritosternal
laciniae and usually have well developed corniculi (horn- to bayonet-shaped).
Species of Macronyssus have more extensive dorsal shields.
Similar
taxa not in key.
Five other families of Mesostigmata are found on reptiles, but none have the
dorsal shielding reduced to a podonotal shield. Members of three other
families of Dermanyssoidea have been described from reptiles: Entonyssidae (in
respiratory tract; lightly sclerotized; peritremes absent), Omentolaelapidae
(body reniform, venter with a fringe of flattened setae), and Ixodorhynichidae
(entire or incised dorsal shield; palp apotele reduced, 1-tined). Several
kinds of trigynaspine mites (with several genital shields) also are associated
with snakes and large lizards, especially species of Ophiomegistus and
Ophiocelaeno.
Ecology & Distribution. The snake mite, Ophionyssus
natricis, is a major pest in zoos and has spread to wild snakes and skinks.
References
Domrow R. 1988. Acari Mesostigmata parasitic on Australian vertebrates:
an annotated checklist, keys and bibliography. Invertebrate Taxonomy 1:
817-948.
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.
Krantz
GW. 1978. A Manual of Acarology.
OSU Bookstores: Corvallis.