Two pink, non-motile, aerobic, alkaliphilic, halotolerant, Gram-negative cocci, designated MIM28(T) and MIM29, were isolated from the surface water of a haloalkaline lake on the Mongolia Plateau. The isolates grew optimally at 30-33 °C, at pH 8-9 and with 3-4 % (w/v) NaCl. The isolates were chemoheterotrophic and could assimilate carbohydrates, organic acids and amino acids. The major respiratory quinone was menaquinone MK-7. The major polar lipids were phosphatidylcholine and phosphatidylethanolamine. The predominant cellular fatty acids were iso-C(15 : 0) (13.8-17.5 %), anteiso-C(15 : 0) (10.5-11.2 %), iso-C(16 : 0) (9.9-13.0 %), C(16 : 0) (4.3-4.6 %), iso-C(17 : 0) (3.8-5.3 %), anteiso-C(17 : 0) (3.7-7.1 %), C(17 : 1)ω6c (4.6-6.4 %), iso-C(17 : 0) 3-OH (4.6-5.8 %), summed feature 3 (C(16 : 1)ω7c and/or C(16 : 1)ω6c; 4.0-6.4 %) and summed feature 9 (iso-C(17 : 1)ω9c and/or C(16 : 0) 10-methyl; 10.4-12.5 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates were most closely related to Litoribacter ruber YIM CH208(T) (93.6 % 16S rRNA gene sequence similarity), the genus Echinicola (90.4-92 %) and other members of the family Cyclobacteriaceae (87.8-90 %). The DNA G+C contents of strains MIM28(T) and MIM29 were 62.8 and 62.2 mol%. On the basis of morphology, physiology, fatty acid composition, phylogeny and 16S rRNA gene sequence analysis, the isolates are assigned to a novel species of a new genus, for which we propose the name Mongoliicoccus roseus gen. nov., sp. nov.; the type strain of the type species is MIM28(T) (= ACCC 05511(T) = KCTC 19808(T)).