Surirella atomus Hustedt 1955, surirelloid diatom, were obtained from Hampyeong Bay, Mu-an,
in the west coast of Korea. We describe the first record of S. atomus in Korea and report its ultrastructure and
molecular characteristics for the first time. For molecular analysis, rbcL gene and cob gene were sequenced.
This species is very small in size, making it difficult to observe its morphological features under a light
microscope. Even with a scanning electron microscope, it has no unique structure in the valve. It is
morphologically very simple. This rare species was known as a marine benthic species. However, it appears
to be widely distributed in marine, freshwater, and brackish environments according to the literature
documenting this species. In terms of phylogeny, S. atomus has been tentatively linked to Petrodictyon gemma,
but the phylogenetic placement of S. atomus seems to be still uncertain, in a manner that is similar to S. febigeri.
However, morphological observations derived from this study suggest that this species belongs to the genus
Surirella