Strain M1-2(T) was isolated from the black sand from the seashore of Jeju Island, Republic of Korea and was classified using a polyphasic taxonomic approach. Strain M1-2(T) appeared as Gram-negative, motile rods that could grow in the presence of 1-10% (w/v) NaCl and at temperatures ranging from 4 to 37°C. This isolate has catalase and oxidase activity and hydrolyses aesculin, DNA and L: -tyrosine. Based on phylogenetic analysis using 16S rRNA gene sequences, strain M1-2(T) belongs to the genus Joostella and is clearly distinct from the other described species of this genus, Joostella marina (type strain En5(T)). The 16S rRNA gene sequence similarity level between M1-2(T) and J. marina En5(T) is 97.2%, and the DNA-DNA relatedness value between the two strains is 23.9%. Strain M1-2(T) contains MK-6 as the major menaquinone and iso-C₁₅:₀, summed feature 3 (C₁₆:₁ ω7c and/or iso-C₁₅:₀ 2OH) and iso-C₁₇:₀ 3OH as major cellular fatty acids. The DNA G + C content is 32.3 mol%. These data suggest that strain M1-2(T) should be classified as a novel species, for which the name Joostella atrarenae sp. nov. is proposed. The type strain for the novel species is M1-2(T) (= KCTC 23194(T) = NCAIM B.002413(T)).