The low surface brightness dwarf members of nearby groups of galaxies

We present the photometric and spectroscopic results of a survey done in a wide-field area of nearby groups and poor clusters. The main goals are identifying and characterizing the properties of low-surface-brightness dwarf galaxies and determining the galaxy luminosity function for Mv>-13. We surveyed areas (typically 0.1--1.0 square degrees) of the groups NGC 6868 (Telescopium), NGC 5846, HCG 42, Hydra I, Dorado and the poor clusters IC 4765 in V and I. In this work we present the results and the analysis of the photometry and spectroscopy done in four groups: HCG 42, NGC 6868, NGC 5846 and IC4765. In these groups, we detected hundreds of new low surface brightness dwarf galaxies. The analysis of their spatial distributions, colors, galaxy luminosity function and other propierties are presented