The anteriormost seta in the r-series, r1, is probably the rarest seta in all of the Monogynaspida. It is clearly present only in some Zerconidae (on the peritrematalperitrematal:
(peritrematic) of or referring to the peritreme; adjectival form of peritreme.
shield). Lindquist and Evans (1965)Lindquist and Evans (1965):
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 considered r1 to be present on the anterior edge of the podonotal shieldpodonotal shield:
the anterior shield in mesostigmatans with divided dorsal shields. 
in some Rhodacaridae, but Lee (1970)Lee (1970):
Lee DC. 1970. The Rhodacaridae (Acari: Mesostigmata); classification, external morphology and distribution of genera. Records of the South Australian Museum 16: 1–219. argued that seta j2 is in an anterior position, r1 is absent, and the setae on the anterior margin are j1, j2, z1, s1.
Author: David E. Walter
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