Redefinition of the Dinoflagellate Genus Alexandrium Based on Centrodinium: Reinstatement of Gessnerium and Protogonyaulax, and Episemicolon gen. nov. (Gonyaulacales, Dinophyceae)

Figure 2

Light (a–j) and scanning electron (k–r) micrographs of Centrodinium intermedium. (a) Several individuals. (b) Left face. (c) Left-ventral view. Note the antapical horn oriented toward the left side. (d) Left and right faces of the same epitheca. The inset shows the apex. (e) Left hypotheca. The inset shows the first antapical plate. The arrowhead points a filiform extension. (f) Right hypotheca. (g) Detail of the sulcal area. (h) Dissociated anterior sulcal plates. The arrowheads point a membranous flange. (i) Anterior lateral sulcal plates. (j) Dissociated posterior lateral sulcal plates. (k–l) Ventral view. (m) Right face. (n) Different antapical horns. (o) Left face. (q–r) Detail of the apex. 1′–4′ = apical plates; 1′′–6′′ = precingular plates; 1′′′–5′′′ = postcingular plates; 1′′′′–2′′′′ = antapical plates; C1–C6 = cingular plates; Po = apical pore plate; S.a. = anterior sulcal plate; s.a.p. = pore of the anterior sulcal plate; S.d.a. = right (dexter) anterior lateral sulcal; S.d.p. = right posterior lateral sulcal; S.m.a. = anterior median sulcal; S.m.p. = posterior median sulcal; S.p. = posterior sulcal. S.s.a. = left (sinister) anterior lateral sulcal; S.s.p. = left posterior lateral sulcal plate. Scale bars (a–m, o) = 20 μm, (n, q–r) = 2 μm.