Eucampia is a common genus of diatoms containing eight known species described from marine waters around the world.It includes the toxic E. zodiacus, a harmful diatom species that has caused much damage to aquacultured seaweed nori, and thus has been the subject of most research on this genus.
Characteristics defining the different Eucampia species are: shape of aperture and ocellus characteristics. If ocellus characteristics are not recognizable, characteristics of elevations are important for identification. In addition, ratio of cell size range and other characteristics are noticeable features (Lee and Lee 2012).
From Lee and Lee 2012:The morphological features of this genus are as follows: bipolar frustules with elliptical valve face, without raphe or pseudoraphe (Hustedt 1930), discoid plastids (Round et al. 1990), bipolar elevations with ocellus (Syvertsen and Hasle 1983), and curved colony formations (Cupp 1943, Kokubo 1955, Hasle and Syvertsen 1996). In general, aperture shape between cells is taken into consideration for the systematic delimitation of species when cells extend after an initial cell division (Hustedt 1930). A single labiate process is located on the central or marginal inter-valve face. The areolae form on the cribra in valve face (Willis et al. 2010). The girdle consists of many intercalary bands (Hasle and Syvertsen 1996, Rivera et al. 2003). These are arranged into ligule-closed and linear-half bands with horizontal punctate striae. Only species from the polar regions have resting spores, e.g., Eucampia antarctica (Fryxell and Prasad 1990, Hasle and Syvertsen 1996). The thickness of their cell wall changes with season (Fryxell 1991). Currently, eight species of the genus Eucampia have been reported around the world (Van Landingham 1969, Fryxell and Prasad 1990, Rivera et al. 2003).