Surprenant polymorphisme des formes immatures chez l acarien plumicole Kiwialges palametrichus (Astigmata, Analgidae). - In Kiwialges palametrichus, the morphology of the larvae and the male nymphs ressembles that of the adults. In contrast, the female nymphs are very different and, also, the female tritonymph differs morphologically from the female protonymph. The authors believe that these differences must be associated with the ecology of the nymphal stages. They suggest that, whereas the adults, male nymphs and larvae live in the plumage of the kiwi, part of the life of the female nymphs is in the skin.