The paper deals with an electrophoretic study of super-oxide-dismutase and esterase isozymes in tritonymph and adult Platynothntspeltifer (C.L. Koch, 1839). In each instar, both proteins exhibit distinct patterns and show the presence of genes "turned on" or "turned off' by regulatory genes. Our observations lead us to discuss a new concept referring to the enzyme-sense organ numerical coevolution in oribatid mites from ecological and evolutionary standpoints. Finally, in order to confirm this concept, we propose to use electrophoretic patterns to place species into ontophylogenetic evolutionary diagrams just as Grandjean (1954) did in the case of sense organs.

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