EXPERIMENT ASYSTEMATICS AND TAXONOMY OF ACARIAcari (or Acarina) is a taxon of arachnids that contains mites and ticks. In most modern treatments, theAcari is considered a subclass of Arachnida and is composed of two superorders: Acariformes (orActinotrichida), Parasitiformes (or Anactinotrichida). Acari are arachnids and, as such, evolved from asegmented body with the segments organised into two tagmata: a gnathosoma (including chelicerae andpalps) and an idiosoma (remaining body). Internal transport and exchange of oxygen and carbon dioxidein some acarine taxa usually are mediated by a branched tracheal system that opens externally throughspiracular ports or stigmata. Stigmata are placed on different parts of body in different orders of Acariand in some orders they are associated with peritremes (See Figs. 1 & 10).