Context : The surface brightness distribution of \sim 30–40 \% of the early-type dwarf galaxies with -18 \leq M _ { B } \leq - 15 in the Virgo and the Coma clusters is fitted by models that include two structural components ( Sèrsic + exponential ) as for bright disc galaxies .

Aims : The goal of the present study is to determine whether early-type dwarf galaxies with a two-component stellar structure in the Virgo and the Coma clusters are low-luminosity copies of bright disc galaxies or are the remnants of bright galaxies strongly transformed by cluster environmental effects .

Methods : I analysed the location of bright disc galaxies and early-type dwarfs in the r _ { b,e } / h – n plane .
The location in this plane of the two-component dwarf galaxies was compared with the remnants of tidally disrupted disc galaxies reported by numerical simulations .

Results : Bright unbarred disc galaxies show a strong correlation in the r _ { b,e } / h – n plane .
Galaxies with larger Sèrsic shape parameters show a higher r _ { b,e } / h ratio .
In contrast , two-component early-type dwarf galaxies do not follow the same correlation .
A fraction ( \sim 55 % ) of them are located outside the locus defined in this plane by having 95 \% of bright disc galaxies .
This distribution indicates that they are not a low-mass replica of bright disc galaxies .
The different location in the r _ { b,e } / h – n plane of two-component early-type dwarfs and bright galaxies can be qualitatively explain whether the former are remnants of disc galaxies strongly transformed by tidal processes .

Conclusions : The progenitors of \sim 20-25 % of early-type dwarf galaxies with -18 \leq M _ { B } \leq - 15 in the Virgo and Coma clusters could be bright disc galaxies transformed by effects of the environment .
These tidally transformed galaxies can be selected according to their location in the r _ { b,e } / h – n plane .