In this paper, the morphological diversity of legs (segments and phaneres) in Trimalaconothrus maniculatus FAIN and LAMBRECHTS, 1987 is studied in larvae and leg IV of nymphs. Progressive and regressive evolutions shown by morphologic characteristics are surveyed to point out their possible relationships with various rules edicted by GRANDJEAN (e.g. the rule of parallel homology, rules of disjunction shown by phaneres, and so on) and discussed in the light of our present knowledge of the phylogeny in oribatids and Malaconothridae.