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Petalodinium sheppeyense
Petalodinium sheppeyense Williams et al., 2015, p.307–308.
Holotype: Williams and Downie, 1966b, pl.20, fig.10, as Wetzeliella (Rhombodinium) glabra. (Williams & Downie 1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182–198., pl. 20, fig. 10, as Wetzeliella (Rhombodinium) glabra. Repository: Natural History Museum (formerly British Museum, Natural History), London; V51972 (fide Williams and Downie 1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182–198., caption to pl. 20, fig 10).)
Age: Ypresian.
Original description: Petalodinium sheppeyense sp. nov.
Diagnosis:
A species of Petalodinium with a rounded apex.
Description:
Large cysts in which the pericyst outline is pentagonal, with a rounded apex and a strongly asymmetrical antapex; the left antapical horn strongly developed and the right antapical horn absent of only weakly developed; lateral horns well developed. Endocyst outline circular to ovoidal. Periphragm smooth; endophragm thicker than periphragm, smooth or ornamented with features of low relief. Circumcavate. Archeopyle latiepeliform; periarcheopyle operculum free; endoarcheopyle may be wider or smaller than periarcheopyle, operculum free.
Discussion: Bujak et al. (1980Bujak JP, Downie C, Eaton GL, Williams GL. 1980. Dinoflagellate cysts and acritarchs from the Eocene of southern England. Special Papers in Palaeontology, no. 24:100 p., p. 29) designated as the holotype of Dracodinium politum the specimen illustrated in Williams & Downie (1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182 198., pl. 20, fig. 9), which has a hyperepeliform archeopyle. Dracodinium politum is now Rhadinodinium politum. Bujak et al. also included in Dracodinium politum the specimen illustrated in their pl. 11, fig. 1, which clearly has a latiepeliform archeopyle. This specimen has the same morphology as that illustrated by Williams & Downie (1966, pl. 20, fig. 10) and assigned by them to Wetzel-iella glabra; thus, we designate the latter specimen as the holotype of the new species Petalodinium sheppeyense.
Holotype: Williams and Downie, 1966b, pl.20, fig.10, as Wetzeliella (Rhombodinium) glabra. (Williams & Downie 1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182–198., pl. 20, fig. 10, as Wetzeliella (Rhombodinium) glabra. Repository: Natural History Museum (formerly British Museum, Natural History), London; V51972 (fide Williams and Downie 1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182–198., caption to pl. 20, fig 10).)
Age: Ypresian.
Original description: Petalodinium sheppeyense sp. nov.
Diagnosis:
A species of Petalodinium with a rounded apex.
Description:
Large cysts in which the pericyst outline is pentagonal, with a rounded apex and a strongly asymmetrical antapex; the left antapical horn strongly developed and the right antapical horn absent of only weakly developed; lateral horns well developed. Endocyst outline circular to ovoidal. Periphragm smooth; endophragm thicker than periphragm, smooth or ornamented with features of low relief. Circumcavate. Archeopyle latiepeliform; periarcheopyle operculum free; endoarcheopyle may be wider or smaller than periarcheopyle, operculum free.
Discussion: Bujak et al. (1980Bujak JP, Downie C, Eaton GL, Williams GL. 1980. Dinoflagellate cysts and acritarchs from the Eocene of southern England. Special Papers in Palaeontology, no. 24:100 p., p. 29) designated as the holotype of Dracodinium politum the specimen illustrated in Williams & Downie (1966Williams GL, Downie C. 1966. Wetzeliella from the London Clay. In: Davey RJ, Downie C, Sarjeant WAS, Williams GL. Studies on Mesozoic and Cainozoic dinoflagellate cysts; British Museum (Natural History) Geology, Bulletin, Supplement 3:182 198., pl. 20, fig. 9), which has a hyperepeliform archeopyle. Dracodinium politum is now Rhadinodinium politum. Bujak et al. also included in Dracodinium politum the specimen illustrated in their pl. 11, fig. 1, which clearly has a latiepeliform archeopyle. This specimen has the same morphology as that illustrated by Williams & Downie (1966, pl. 20, fig. 10) and assigned by them to Wetzel-iella glabra; thus, we designate the latter specimen as the holotype of the new species Petalodinium sheppeyense.