A Gram-negative, rod-shaped bacterial strain, designated K19414(T), was isolated from a chironomid (Diptera; Chironomidae) egg mass which was sampled from Kishon River in northern Israel. Phylogenetic analysis based on the 16S rRNA gene sequence positioned the novel strain among the genus Rheinheimera, with closest similarity to Rheinheimera pacifica KMM 1406(T). The levels of similarity to type strains of Rheinheimera species were lower than 96.5 %. Isolate K19414(T) is aerobic, motile by means of a single polar flagellum, catalase-negative and oxidase-positive; growth was observed at salinities of 0-2 % NaCl and the temperature for growth ranged from 4 to 40 degrees C. The major cellular fatty acids are 16 : 0 (14.8 %) and 16 : 1 omega 7c and/or 15 : 0 iso 2-OH (25.76 %). The DNA G+C content is 49.9 mol%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain K19414(T) (=LMG 23818(T) =DSM 18694(T)) was classified in the genus Rheinheimera as the type strain of a novel species, for which the name Rheinheimera chironomi sp. nov. is proposed.