Description of Stieleria mannarensis sp. nov., isolated from a marine sponge, and proposal to include members of the genus Roseiconus in the genus Stieleria.

A pink-coloured, salt- and alkali-tolerant strain, JC639T, was isolated from a specimen of the marine sponge Spheciospongia sp. The novel isolate is motile, aerobic and forms oval to pear-shaped cells. It shares the highest 16S rRNA gene sequence identity with Stieleria neptunia Enr13T and Stieleria maiorica Mal15T in the family Pirellulaceae (phylum Planctomycetota). Optimum pH and temperature for growth are 8.0 (range 7.0-10.0) and 25 °C (range 10-30 °C), respectively. Major fatty acids are C15:1ω8c, C16:0, C18:1ω9c, C18:0, and C16:1ω7c/C16:1ω6c. Major polar lipids are phosphatidylcholine and phosphatidylethanolamine. The genome of strain JC639T has a size of 9.56 Mb and a DNA G + C content of 59.5%. The polyphasic analysis of the isolate supports its delineation from the known species in the genus Stieleria. We therefore introduce Stieleria mannarensis sp. nov., represented by JC639T (= KCTC 72168T = NBRC 113878T) as the type strain. Based on an analysis of established phylogenomic markers performed with all current members of the overlapping genera Stieleria and Roseiconus, we further propose to include the two so far characterized Roseiconus species in the genus Stieleria.