Alexandrium, Halim, 1960

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 : 542

3.1.1 Alexandrium a ffi ne (Inoue et Fukuyo) Balech ( Figures 2–8 )

References: Balech 1995, 55, pl. XIII, figs 20–36; Usup et al. 2002, 267, figs 2 A–D; Gu et al. 2013, 72, figs 2 A–D; Lassus et al. 2016, 42, pl. 2 A–E; Kim et al. 2017, 428, figs 1 A–L.

Synonyms = Protogonyaulax affine Inouye et Fukuyo

Chain-forming species, with chains of 3–8 cells observed ( Figures 2 and 3 ). Individual cells of medium-size, slightly longer than wide ( Figures 2 and 3 ). The epitheca is domed to conical, cingulum excavated and the hypotheca is concave ( Figure 4 ). The first apical plate (1′) is rhomboidal, in contact with Po, and with a small ventral pore on its right margin ( Figures 5 and 6 ). The apical complex pore is conspicuous, with a large connecting pore and a relatively small foramen, both aligned in the same axis ( Figures 6 and 7 ). The posterior sulcal plate (Sp) has a small pore and the two anterior ends are projected ( Figure 8 ).

Measurements: 30–43 µm length (L), 33–43 µm width (W) (Table 1).

Toxicity: this is a species that produces saxitoxins at very low concentrations, so they do not represent a risk of poisoning ( Kim et al. 2023).

Distribution: in the southern part of the Gulf of California.

Figures

Figures 2–8: Alexandrium affine, LM. (2, 3) Chains of 8 and 3 cells, respectively. (4) An empty cell showing only the theca in ventral view. (5) Epitheca in ventral view showing the ventral pore (arrow) in the first apical plate (1′). (6) Epitheca with Po and 1′ showing the ventral pore (arrow). (7, 8) Po and posterior sulcal plate (Sp) (with a connecting pore), respectively.