LIGHT MICROSCOPY AND ELECTRON MICROSCOPY OF NEPHROSELMIS SPINOSA SP. NOV. (PRASINOPHYCEAE,CHLOROPHYTA)1

Nephroselmis spinosa Suda sp. nov. is described based on LM and EM observations. Two strains of N. spinosa (S222 and SD959‐3) were isolated from sand samples collected from the northwest coast of western Australia. The cells were remarkably right–left flattened and appeared ellipse or bean‐shaped when viewed from their right or left side. A single, parietal, crescent chloroplast was pale green to yellowish green and contained one conspicuous eyespot in its anterior ventral edge near the base of the short flagellum. A pyrenoid with three starch plates was located at the dorsal of the chloroplast. The cells divided by transverse binary cell division, as is common in other species of this genus. This alga possessed four types of body scales, and three scale types were similar to N. olivacea Stein and N. astigmatica Inouye & Pienaar. However, the fourth and outermost scale type was distinctive because although it was a spiny stellate scale with nine spines, one of them extended about 1 μm and was slightly curved with a hook at the end. This scale morphology, an important taxonomic characteristic, has never been described for the genus Nephroselmis. The cell's morphology, pyrenoid structure, hair scales, and cell size were distinctive from previously described Nephroselmis species, and its unique scale characteristic led me to name this newly proposed species “spinosa,” meaning spiny.