A polyphasic taxonomic study was performed on six strains of an unknown Gram-positive, non-motile, spore-forming, short oval to rod-shaped bacterium isolated from a swine-manure storage pit. In addition to these strains, an isolate deposited in the Culture Collection of the University of Göteborg (Sweden) was found to be biochemically related to the manure strains. The major end products of metabolism included acetate and succinate but not butyrate. Comparative 16S rRNA gene sequencing confirmed that all these isolates were closely related to each other and formed a hitherto unknown lineage within the clostridial rRNA XIVa cluster of organisms. On the basis of phylogenetic, biochemical and phenotypic evidence, it is proposed that the unknown bacterium represents a novel genus and species, for which the name Robinsoniella peoriensis gen. nov., sp. nov. is proposed. The type strain of Robinsoniella peoriensis is PPC31T (=CCUG 48729T =NRRL B-23985T).