Several species of the genus Pseudo-nitzschia produce the neurotoxin domoic acid (DA) known to be responsible for amnesic shellfish poisoning. Recently off the coast of Geomundo and in Exclusive Economic Zone (EEZ) of Korea Strait, P. cf. brasiliana predominated in summer, 2010. As P. cf. brasiliana was new to Korea, we describe the morphological characteristics of the species. It was observed that cells were linear to lanceolate in valve and girdle view, $51{sim}76{mu}m$ long and $1.9{sim}2.6{mu}m$ wide. In the central part a large interspace was absent. The number of fibulae and striae in $10{mu}m$ were 30~37 and 31~37. Each stria contained 2~3 rows of poroids, with 10 to 14 poroids in $1{mu}m$ length. These morphological features of P. cf. brasiliana were found to be similar with the P. brasiliana, except with the fact that P. cf. brasiliana carred more numbers of fibulae/striae in $10{mu}m$ and poroids in $1{mu}m$. Based on our observation, we suggest that P. cf. brasiliana is a newly identified Pseudo-nitzschia species or a variety of P. brasiliana.