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Hiddenocysta
Etymology. In reference to Hidden Basin (Nelson Island, British Columbia, Canada) where similar cysts were reported by Dobell and Taylor (1981).
Type species. Hiddenocysta matsuokae sp. nov.
Diagnosis. Skolochorate cyst with spherical to ovoid central body bearing gonal and intergonal processes reflecting a gonyaulacacean tabulation (?3–4´, 6´´, 5´´´, 1p, 1´´´´). Processes connected or not by crests.. Compound archeopyle consisting of 3´´ and 4´´, operculum free.
Remarks. This cyst was first reported by Dobell and Taylor (1981) in surface sediments from Hidden Basin (BC, Canada), whom considered it to belong to the genus Spiniferites (Spiniferites sp. 1 and S. sp. 2).
Comparison. Hiddenocysta’s 2P precingular archeopyle distinguishes the genus from Spiniferites and Achomosphaera, which have a single (3´´) plate archeopyle. A further. difference with Spiniferites is that the latter genus always has pronounced crests connecting the process bases, which are often absent in Hiddenocysta. The genus Achomosphaera, on the other hand, never has crests (Mertens et al. 2018). The extant genus Bitectatodinium has a similar 2P precingular archeopyle but is “without obvious surface projections” (Wilson 1973). A number of Mesozoic cyst genera have a similar general appearance and a two-plate archeopyle, but each can be distinguished from Hiddenocysta: Kiokansium (Duxbury 1983) has a smooth wall, simpler processes and a complete absence of tabulation; Taleisphaera (Masure 1986) has diagnostic penitabular crests; Pulchrasphaera (Schiøler et al. 1997) has low non-tabular ornamentation; Nexosispinum (Davey 1979) has anastomosing processes; Corradinium (Masure 1986) mainly has intratabular processes; Gongylodinium (Fenton et al. 1980) is non-tabulate and does not bear processes; and Occisucysta (Gitmez 1970) is characterized by a pronounced apical boss and denticulate or spiny sutural crests. The genera Durotrigia, Dissiliodinium and Cavatodissiliodinium have a multiplate precingular archeopyle but which most often involves more than two plates (Feist-Burkhardt and Monteil 2001). Furthermore, species of Dissiliodinium are characterized by negative structures (i.e., grooves), Cavatodissiliodinium is cavate, and Durotrigia species have ridges and septae, but no processes (Feist-Burkhardt and Monteil 2001).
Type species. Hiddenocysta matsuokae sp. nov.
Diagnosis. Skolochorate cyst with spherical to ovoid central body bearing gonal and intergonal processes reflecting a gonyaulacacean tabulation (?3–4´, 6´´, 5´´´, 1p, 1´´´´). Processes connected or not by crests.. Compound archeopyle consisting of 3´´ and 4´´, operculum free.
Remarks. This cyst was first reported by Dobell and Taylor (1981) in surface sediments from Hidden Basin (BC, Canada), whom considered it to belong to the genus Spiniferites (Spiniferites sp. 1 and S. sp. 2).
Comparison. Hiddenocysta’s 2P precingular archeopyle distinguishes the genus from Spiniferites and Achomosphaera, which have a single (3´´) plate archeopyle. A further. difference with Spiniferites is that the latter genus always has pronounced crests connecting the process bases, which are often absent in Hiddenocysta. The genus Achomosphaera, on the other hand, never has crests (Mertens et al. 2018). The extant genus Bitectatodinium has a similar 2P precingular archeopyle but is “without obvious surface projections” (Wilson 1973). A number of Mesozoic cyst genera have a similar general appearance and a two-plate archeopyle, but each can be distinguished from Hiddenocysta: Kiokansium (Duxbury 1983) has a smooth wall, simpler processes and a complete absence of tabulation; Taleisphaera (Masure 1986) has diagnostic penitabular crests; Pulchrasphaera (Schiøler et al. 1997) has low non-tabular ornamentation; Nexosispinum (Davey 1979) has anastomosing processes; Corradinium (Masure 1986) mainly has intratabular processes; Gongylodinium (Fenton et al. 1980) is non-tabulate and does not bear processes; and Occisucysta (Gitmez 1970) is characterized by a pronounced apical boss and denticulate or spiny sutural crests. The genera Durotrigia, Dissiliodinium and Cavatodissiliodinium have a multiplate precingular archeopyle but which most often involves more than two plates (Feist-Burkhardt and Monteil 2001). Furthermore, species of Dissiliodinium are characterized by negative structures (i.e., grooves), Cavatodissiliodinium is cavate, and Durotrigia species have ridges and septae, but no processes (Feist-Burkhardt and Monteil 2001).