Primitively, sarcoptiform mites have an anterior median projection of the idiosoma called a naso. When present, this structure often bears the anteriormost pair of prodorsal setaeprodorsal setae:
the setae on the prodorsum of acariform mites. Two competing chaetotactic systems are used for designations: the Rostral-lamellar and Vertical-scapular systems. 
, the internal vertical setae (vi).
Author: David E. Walter
Content last updated Sept. 2006, unless indicated otherwise
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