Lactobacillus plantarum belongs to the Lactobacillus caseiPediococcus phylogenetic group of the genus Lactobacillus (Hammes & Vogel, 1995) and in particular to the L. plantarum phylogenetic subgroup (Hammes & Hertel, 2003). This species is characterized by many metabolic activities that allow it to colonize different environments such as dairy products, pickled vegetables, fish products, silage, wine as well as mammal intestinal tracts (Vescovo et al., 1993). The species is highly heterogeneous (Dellaglio et al., 1975). Several studies, which have tried to elucidate intraspecific relationships, led to the description of two novel species: Lactobacillus pentosus and Lactobacillus paraplantarum (Zanoni et al., 1987;Curk et al., 1996). These three closely related species cannot be distinguished by 16S rRNA gene sequence analysis because they show 99 % sequence similarity. They also have very similar fermentation abilities: L. pentosus can be differentiated from L. plantarum only by its capacity to ferment glycerol and xylose (Zanoni et al., 1987). Some exceptions, however, exist: some L. plantarum strains are able to metabolize glycerol as with L. pentosus and not all L. pentosus strains can metabolize xylose . Fermentation differences between L. plantarum and L. paraplantarum are even less helpful: the main difference is that strains of the latter species metabolize methyl a-D-glucopyranoside, whereas 66 % of L. plantarum strains cannot .With regard to molecular techniques, L. plantarum, L. pentosus and L. paraplantarum can be rapidly distinguished using PCR amplification targeting the 16S/23S rRNA gene spacer region (Berthier & Ehrlich, 1998) or the recA gene as described by Torriani et al. (2001). Moreover, a polyphasic approach with a combination of RAPD (randomly amplified polymorphic DNA)-PCR, Southern hybridization and phenotypic traits not only distinguished the three species L. plantarum, L. paraplantarum and L. pentosus, but also revealed the presence of two groups of strains in the species L. plantarum (Bringel et al., 2001): 90 % of these were closely linked to the L. plantarum type strain, ATCC 14917 T , and 10 % (14 strains) formed a distinct group. We report here the analyses performed on those 14 'atypical' strains and, on the basis of collected data, a novel subspecies of L. plantarum is proposed.