) continued (The diagnostic trait of P. volzii var. australe G. S. West is the antapical plates of unequal size (versus equal size in P. volzii var. volzii), and this character state is frequent (> 70 %) in the material under investigation (Fig. 3 i). Similarly, the diagnostic trait of P. volzii var. cinctiforme M. Lefèvre is the apical plates 2 ′ and 4 ′ of unequal size (versus rather equal size in P. volzii var. volzii), and this character state (distinctive in species such as P. cinctum and Peridinium raciborskii Wołosz.) is also not rare (25 ‒ 50 %) in the material studied here (Fig. 3 k). We even confirm the existence of Peridinium guestrowiense subvar. originale Er. Lindem. having six postcingular plates (versus five such plates usually present in peridinialean dinophytes; Fig. 3 i). The reduction from six to five postcingular plates in Peridiniales may result from a fusion of the third and fourth postcingular plate (Gottschling et al., 2021) present today in dinophytes s

) continued (2 Table
Image3 k3 l––3 m[n = 100 forRibotype (frequency) each ribotype]I (26%), II (29.5 %), III (41.5 %)I (5%), II (2%), III (1%)I (–), II (–), III (–)I (–), II (–), III (–)I (1%), II (1 %), III (1%)Cingulum displacement––1.5 ×0.5 ×1.5 ×Length / width [μm]–– 40 ‒ 50 / –52 ‒ 60 / 55 ‒ 6035 ‒ 50 / 25 ‒ 45Diagnostic trait (s)Plates 2 ′ and 4 ′ very unequal in size Plates 1 ‴ and 2 ′ ‴ fusedAPC presentOrnamentation with linear ridges Plate 3 ′ splitBasionym, protologueP. volzii var. cinctiforme M. Lefèvre, Bulletin du Museum d’Histoire Naturelle. Paris 33: 122 (1927)P. volzii var. simplex M. Lefèvre, stat. corr. (ICN Art. 24.4.), Bulletin du Museum d’Histoire Naturelle. Paris 33: 122 (1927)P. playfairii Er. Lindem., Archiv für Hydrobiologie 8 Suppl.: 715 – 716, Figs 43 – 44 (1931)P. vancouverense Wailes, nom. nov. pro P. striolatum Wailes, Annales de Protistologie 3: 110 (1931)P. volzii forma complexum Krakhmalny in Krakhmalny, Wasser, Nevo, Boltovskoy, Barinova & Krakhmalny, International Journal of Algae 6: 214, Fig. 2, pl. II 3 – 6 (2004)