Description:—Thallus blue-green. Filaments straight or coiled, uniseriate, without false branching, 1.75–2.28 μm wide. Sheath thin, colorless, attached to trichomes. Trichomes cylindrical, distinctly constricted at the cross wall. Cells longer than wide, 2.23–3.46 μm long and 1.04–1.73 μm wide. Apical cells rounded, sometimes extended, without calyptra, longer than wide, 1.86–3.66 μm long and 1.24–1.85 μm wide. Thylakoids parietal, varying from three to four at the lateral portion. No heterocytes. Gas vesicles absent. Cyanophycin granules (CG) and lipid droplet (ld) present.

Etymology:— “sina ” refers to the sampling site Xincun Bay in Hainan Province, China.

Habitat: —epiphytic on Thalassia hemperichii.

Type locality: — CHINA. Xincun Bay, Lingshui County, Hainan Province, 18°24’42’’N, 109°59’6’’E, 24 May 2014. (Ecology: pH 8.09; Conductivity 40.79 ms/ ccm; dissolved oxygen 103.8% sat; salinity 26.4‰).

Holotype: A monospecific dried sample in liquid nitrogen has been deposited in the China Center For Type Culture Collection (CCTCC); accession number M 2015061

Observation: —Trichomes colonized the bottom of the flask when the strain was cultivated in modified liquid BG-11 medium. Distinct constrictions at the cross wall and rounded terminal cell were evident in SEM images (Fig. 2 a-e). The ultrastructure of SCSIO T- 2 showed the central nucleoid, thin, fibrous monolayer sheath and thylakoids occurred at the lateral portions of cell.