A Gram-negative ultramicrobacterium (designated strain UMB49(T)) was isolated from a 120,000-year-old, 3,042 m deep Greenland glacier ice core using a 0.2 mum filtration enrichment procedure. Phylogenetic analysis of the 16S rRNA gene sequence indicated that this strain belonged to the genus Herminiimonas of the family Oxalobacteraceae of the class Betaproteobacteria. Strain UMB49(T) was most closely related to Herminiimonas saxobsidens (99.6 % sequence similarity), Herminiimonas arsenicoxydans (98.4 %), Herminiimonas aquatilis (97.6 %) and Herminiimonas fonticola (97.9 %). Genomic DNA-DNA hybridization showed low levels of relatedness (below 57 %) to H. saxobsidens and H. arsenicoxydans. Cells of strain UMB49(T) were small thin rods with a mean volume of 0.043 mum(3) and possessed 1 or 2 polar and/or 1-3 lateral very long flagella. The original colony pigmentation was brown-purple but after recultivation the colonies were translucent white to tan coloured. Strain UMB49(T) grew aerobically and under microaerophilic conditions. The strain produced catalase and oxidase, but did not reduce nitrate. Sole carbon sources included citrate, succinate, malate, lactate and alanine. The strain produced acid from l-arabinose, d-arabinose, l-xylose, d-xylose and d-ribose. The DNA G+C content was 59.0 mol%. Based on differential characteristics of strain UMB49(T) and recognized Herminiimonas species, it was concluded that strain UMB49(T) represents a novel species of the genus Herminiimonas, for which the name Herminiimonas glaciei sp. nov. is proposed. The type strain is UMB49(T) (=ATCC BAA-1623(T)=DSM 21140(T)).