Observations on Postembryonic Development in Eutrombicula Splendens (Acari-Acariformes)1

Abstract
Posternbryonic development in Eutrombicula Splendens includes the following instars: prelarva, larva, protonymph, deutonymph, tritonymph, and adult. Prelarva and larva bear Claparede's organ; the protonymph, deutonymph, tritonymph, and adult bear 1, 2, 3 and 3 pairs of genital papillae, respectively. Larva, deutonymph, and adult are active instars whereas the prelarva, protonymph, and tritonymph are calyptostatic (quiescent, regressive) instars. The cyclical pattern of active and calyptostatic instars in parasitengone mites is unique among Arthropoda. Each active instar is preceded by a molt followed by ecdysis. No ecdysis accompanies the molt preceding the calyptostatic instars; these instars are entirely pharate. The terminology applicable to periods of “discontinuous” development is briefly discussed. The interval delimited by molts is called a stasis; the animal itself during a stasis is called an instar. The supposed pupal nature of calyptostatic instars is discussed.

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