Alexandrium monilatum (Howell) Balech, 1995

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

3.1.7 Alexandrium monilatum (Howell) Balech ( Figures 28–37 )

References: Balech 1995, 67, pl. XV, figs 1–16; Faust and Gulledge 2002, pl. 4 fig. 1; Taylor et al. 2003, 406, fig. 15.16; Lassus et al. 2016, 50; Hernández-Becerril et al. 2021, 70, 71.

Chain-forming species ( Figures 28–30 ), with medium to long chains (up to 8 cells per chain), cells strongly depressed, longer than wide, with an evident apical pore ( Figures 31 and 32 ). Convex epitheca, wide and excavated cingulum and concave hypotheca ( Figure 31 ). The first apical plate (1′) is not in connection with Po ( Figures 32–34 ), which is a large structure, with a comma-shape and a large connecting pore ( Figures 34 and 36 ). The posterior sulcal plate (Sp) is rhomboid and has a large pore ( Figures 35 and 37 ).

Measurements: 38–46 μm L, 45–63 μm W (Table 1).

Toxicity: this species produces gonoidomin A, toxin that causes hemolysis to erythrocytes in mammalian species, including humans ( May et al. 2010).

Distribution: in the Gulf of Tehuantepec.

Figures

Figures 28–37: Alexandrium monilatum, LM and SEM.(28, 29) A long chain (8 cells) and detail of that chain,respectively,LM. (30) Pair of cells in ventral view,SEM.(31) General outline of a cell, LM.(32) Cell in ventral view showing Po and 1′, SEM. (33) Detail of the cingulum and sulcus, showing the first apical plate (1′), SEM. (34) Apical view with plate tabulation, SEM. (35) Hypotheca showing the posterior sulcal plate (Sp) and its connecting pore (arrow), SEM.(36) Po plate with the conjunction pore and foramen, SEM. (37) Posterior sulcal plate showing the connection pore, LM.