Many early derivative lineages of Mesostigmata have adults covered dorsally by a complex of shields of various sizes, a condition that is typical of immature stages. This 'fragmentation' of dorsaldorsal:
relating to the upper or back side; opposed to ventral.
shields also occurs in some derived lineages.
In many other groups the dorsumdorsum:
the upper or back side; opposed to venter.
is covered by two more or less equal shields, an anterior podonotalpodonotal:
relating to the dorsal podosoma, the region of the idiosoma over the legs.
and a posterior opisthonotal shieldopisthonotal shield:
the posterior shield in mesostigmatans with divided dorsal shields.
. Rarely, the anterior shield may have deep notches or lateral incisions.
In many groups of Monogynapsida the dorsumdorsum:
the upper or back side; opposed to venter.
of the adult female is covered by a single, entire holodorsal shieldholodorsal shield:
a shield that covers all of the dorsum. In Mesostigmata, the holodorsal shield is often interpreted as resulting from the fusion of podonotal and opisthonotal shields and a suture between these regions is often visible (see recurved and procurved).
, typically oval to subrectangular in shape, or sometimes taperingtapering:
drawn out or with margins converging.
posteriorly an resembling an inverted teardrop or spear point.
Rarely, the dorsaldorsal:
relating to the upper or back side; opposed to ventral.
shield may be truncated posteriorly, leaving most of the opisthosomaopisthosoma:
(= abdomen) the posterior body division in arachnids; usually not distinct in mites because of the fusion of the opisthosoma with part of the prosoma to form the idiosoma.
uncovered.
Some groups have relatively shallow to deep incisions at the level where the podonotalpodonotal:
relating to the dorsal podosoma, the region of the idiosoma over the legs.
and opisthonotalopisthonotal:
dorsal opisthosoma.
shields would fuse. In a few mites, e.g., some Phytoseiidae, shallow notches occur in the podonotalpodonotal:
relating to the dorsal podosoma, the region of the idiosoma over the legs.
region.
Author: David E. Walter
Content last updated Sept. 2006, unless indicated otherwise
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