Protoperidinium conicum (Gran) Balech 1974 . Rev. Mus. Argent. Cienc. Nat. “ B. Rivadavia ”, Hydrobiologia 4 (1): 58. (Fig. 32) .

References: Paulsen 1908: 58, Fig. 74; Lebour 1925: 111, Pl. XIX, Fig. 1a–d; Abé 1927: 406, Fig. 24; Schiller 1937: 233, Fig. 229 a–j; Kiselew 1950: 195, Fig. 326 a–b, 332 a–v; Abé 1981: 371, Fig. 55 (375–381) (as Peridinium conicum); Balech 1988: 87, Pl. 26, Figs. 1–4; Steidinger & Tangen 1997: 538, Pl. 52; Okolodkov 2008: 120, Pl. 6, Figs. 11–14; Konovalova & Selina 2010: 143, Table XVI, 1–5; Al-Yamani & Saburova 2019: 303, Pl. 166.

Basionym: Glenodinium conicum Gran 1902 . Rep. Norweg. Fishery Mar. Investigat. 2 (5): 185, 189, Fig. 14.

Synonyms: Peridinium divergens var. conica Gran 1900, Peridinium conicum (Gran) Ostenfeld & Schmidt 1901 .

Description: Cells pentagonal, dorsoventrally compressed. The apical pore structure of Aʹ– type (Toriumi & Dodge 1993). The epithecal plate pattern comprises seven precingular plates (7ʹʹ), four apical plates (4ʹ), three anterior intercalary plates (3a), 1ʹ and 2a plates of “ortho”–”hexa” type. Thecal plates with reticulations and pores. The cingulum median, deep, narrow, bordered. The sulcus deep and expands distally more towards the right than towards the left. The hypotheca with low conical antapical horns; each horn bears a small spine at its end. The cellular contents pink or colorless. Dimensions: 65–100 μm long and 64–94 μm wide.

Distribution: Coastal and oceanic; cosmopolitan in temperate to tropical waters (Steidinger & Tangen 1997).

Data on the distribution of P. conicum are given from the GBIF.org (2022) (Fig. 82).