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Downiesphaeridium
From Williams et al., 2017:
[Downiesphaeridium, Islam, 1993, p. 83; Emendation: Masure in Fauconnier and Masure, 2004, p.195
Type species: originally as Cleistosphaeridium spinulastrum, Islam, 1983b (pl.2, fig.1)] ; Downiesphaeridium spinulastrum, Islam, 1993
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Original description: [Islam, 1993]:
Diagnosis:
Spherical to subspherical dinoflagellate cysts; auto or biphragmal, psilate or ornamented (chagrinate, echinate, granulate, reticulate); skolochorate; possesses many nontabular processes which are hollow, taeniate, tapering or attenuate with broader bases, distally acuminate, rimmed or simple, both ends closed; processes in individual specimens are similar in size and shape; tabular features other than the tA or (tA) type apical archeopyle are normally absent.
Affinities:
Downiesphaeridium resembles Dapsilidinium Bujak, Downie, Eaton and Williams, 1980 but differs in possessing attenuate/tapering and distally closed processes. Conosphaeridium Cookson and Eisenack, 1969 possessing hollow closed conical processes differ from the new genus in having fewer broader processes and a precingular archeopyle.
Remarks:
Creation of the new genus was considered necessary to accommodate the dinoflagellate cysts possessing attenuate/tapering hollow closed processes and apical type tA or (tA) archeopyle, and appropriate as these cysts do not conform to the morphology of any existing fossil dinoflagellate genera.
[Downiesphaeridium, Islam, 1993, p. 83; Emendation: Masure in Fauconnier and Masure, 2004, p.195
Type species: originally as Cleistosphaeridium spinulastrum, Islam, 1983b (pl.2, fig.1)] ; Downiesphaeridium spinulastrum, Islam, 1993
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Islam, 1993]:
Diagnosis:
Spherical to subspherical dinoflagellate cysts; auto or biphragmal, psilate or ornamented (chagrinate, echinate, granulate, reticulate); skolochorate; possesses many nontabular processes which are hollow, taeniate, tapering or attenuate with broader bases, distally acuminate, rimmed or simple, both ends closed; processes in individual specimens are similar in size and shape; tabular features other than the tA or (tA) type apical archeopyle are normally absent.
Affinities:
Downiesphaeridium resembles Dapsilidinium Bujak, Downie, Eaton and Williams, 1980 but differs in possessing attenuate/tapering and distally closed processes. Conosphaeridium Cookson and Eisenack, 1969 possessing hollow closed conical processes differ from the new genus in having fewer broader processes and a precingular archeopyle.
Remarks:
Creation of the new genus was considered necessary to accommodate the dinoflagellate cysts possessing attenuate/tapering hollow closed processes and apical type tA or (tA) archeopyle, and appropriate as these cysts do not conform to the morphology of any existing fossil dinoflagellate genera.