Xing, ZZ (reprint author), CCAST, World Lab, POB 8730, Beijing 100080, Peoples R China.
We show that there exist six parallel textures of the charged lepton and neutrino mass matrices with six vanishing entries, whose phenomenological consequences are exactly the same. These isomeric lepton mass matrices are compatible with current experimental data at the 3sigma level. If the seesaw mechanism and the Fukugita-Tanimoto-Yanagida hypothesis are taken into account, it will be possible to fit the experimental data at or below the 2sigma level. In particular, the maximal atmospheric neutrino mixing can be reconciled with a strong neutrino mass hierarchy in the seesaw case. (C) 2004 Elsevier B.V. All rights reserved.