The genus Serratia belongs to the family Enterobacteriaceae of the class Gammaproteobacteria. Some members of the genus Serratia have clinical importance (Grimont & Grimont, 1992;Brenner, 1984) and other members produce pigments identified as prodigiosin (Hearn et al., 1970;Gerber, 1975). A subspecies of Serratia marcescens (S. marcescens subsp. sakuensis) and a urea-dissolving species (Serratia ureilytica) have been described previously by Ajithkumar et al. (2003) and Bhadra et al. (2005), respectively. In this paper, a red-pigmented, non-sporeforming, fluorescent strain, designated DZ0503SBS1 T , was isolated from the intestine of the nematode Heterorhabditidoides chongmingensis (Zhang et al., 2008).The novel strain was associated symbiotically with the entomopathogenic nematode H. chongmingensis (Rhabdi3These authors contributed equally to this work.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain DZ0503SBS1 T is EU036987.A neighbour-joining phylogenetic tree based on partial rpoB gene sequences, a fluorescence micrograph showing the location of strain DZ0503SBS1 T in the intestine of the nematode Heterorhabditidoides chongmingensis, a transmission electron micrograph of strain DZ0503SBS1 T , cellular fatty acid composition data and similarity coefficient values of strain DZ0503SBS1T and related taxa are available with the online version of this paper.