References: Nguyen and Larsen 2004, 93, pl. 7, figs 1–8; Alvarado et al. 2015, 3, figs 2 a–c.

Solitary cells, ovoid, slightly depressed longitudinally, epitheca and hypotheca about the same proportion (Figure 12), wide and excavated cingulum (Figures 13 and 14), smooth theca (Figures 14–17) with scattered pores; the nucleus is central, to the left side (Figure 12). The first apical plate (1′) is not in connection with Po, is asymmetrically pentagonal and has a small ventral pore between this plate and 4′ (Figures 13 and 15), whereas 2′ and 4 ʹ are large plates, and plate 6″ is rhomboid (Figure 15). Po is elongate and more triangular (Figure 17). The posterior sulcal plate (Sp) is oblique pentagonal, longer than wide, with no apparent pore (Figure 18). Some particular plates of the epitheca, cingulum and sulcus were also observed (Figure 19).

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

Toxicity: this species is not considered to be toxic (Long et al. 2021).

Distribution: in the Gulf of Tehuantepec.

L, length; W, width; PSP, paralytic shellfish poisoning.