Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo

Hernández-Becerril, David U., Pichardo-Velarde, Jorge G., Alonso-Rodríguez, Rosalba, Maciel-Baltazar, Ebodio, Morquecho, Lourdes, Esqueda-Lara, Karina, Barón-Campis, Sofía A. & Quiroz-González, Nataly, 2023, Diversity and distribution of species of the planktonic dinoflagellate genus Alexandrium (Dinophyta) from the tropical and subtropical Mexican Pacific Ocean, Botanica Marina (Warsaw, Poland) 66 (6), pp. 539-557 : 545-547

3.1.8 Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo ( Figures 38–43 )

References: Balech 1995, 73, pl. XVI, figs 1–18; Nguyen and Larsen 2004, 102, pl. 13, figs 1–3; Gu et al. 2013, 75, figs 4 A–D; Lassus et al. 2016, 53, pl. 9 A–D; Hernández-Becerril et al. 2021, 70, 71.

Solitary cells of medium to relatively large size, ovoid to pentagonal and slightly depressed longitudinally ( Figure 38 ), epitheca slightly domed and shorter than hypotheca ( Figures 38 and 39 ), which has an antapical concavity, cingulum wide and excavated ( Figure 41 ), and sulcus wide and deep ( Figures 38 and 39 ). First apical plate (1′) is not connected to Po ( Figure 39 ) and has a pentagonal shape ( Figures 39, 41 , and 42) and a strong posterior indentation (notch). A large ventral pore appears between this plate and 4′ ( Figures 39, 41–43 ), whereas 6″ is quadrangular. Po is elongate with a classical comma shape ( Figure 40 ).

Measurements: 35–42 μm L, 40–45 μm W (Table 1).

Toxicity: this species produces goniodomins A and B ( Krock et al. 2018).

Distribution: in the Gulf of Tehuantepec.

Figures

Figures 38–43: Alexandrium pseudogonyaulax, LM. (38) Cell in ventral view. (39) Empty cell in ventral view, showing 1′, 4′, 6″ and the large ventral pore (arrow). (40) Detail of Po with the foramen. (41–43) Epitheca in ventral view showing 1′, 4′, 6″, and ventral pore (arrow).