類似 Alexandrium minutum
The cysts of similar to the discoid cysts of A. lusitanicum Balech (Bolch et al 1991). A. minutum is an unchained species that is well characterized morphologically (see Balech, 1995). However, some specimens identified as A. minutum differ morphologically from the species redescription (Balech, 1989), especially concerning their plate ornamentation (Montresor et al., 1990), and the lack of a ventral pore (Danish specimens in Hansen et al., 2003). Whereas in most observations theca appears smooth, without a reticulation pattern (e.g. Vila et al., 2005), there are some specimens that show plate ornamentation in the hypotheca (Montresor et al., 1990). These observations and their wide geographical distribution suggest that more than a single species could be included under the name of A. minutum (Moestrup et al., 2002). A. lusitanicum was described as a distinct species based on the different shape of the s.a. plate (Balech, 1995). However, Franco et al., (1995) suggested that A. lusitanicum and A. minutum are conspecific in view of the apparent variability of this feature.